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Bibliography on: Biofilm

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ESP: PubMed Auto Bibliography 22 Jan 2021 at 01:34 Created: 

Biofilm

Wikipedia: Biofilm A biofilm is any group of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular polymeric substances (EPS). The EPS components are produced by the cells within the biofilm and are typically a polymeric conglomeration of extracellular DNA, proteins, and polysaccharides. Because they have three-dimensional structure and represent a community lifestyle for microorganisms, biofilms are frequently described metaphorically as cities for microbes. Biofilms may form on living or non-living surfaces and can be prevalent in natural, industrial and hospital settings. The microbial cells growing in a biofilm are physiologically distinct from planktonic cells of the same organism, which, by contrast, are single-cells that may float or swim in a liquid medium. Biofilms can be present on the teeth of most animals as dental plaque, where they may cause tooth decay and gum disease. Microbes form a biofilm in response to many factors, which may include cellular recognition of specific or non-specific attachment sites on a surface, nutritional cues, or in some cases, by exposure of planktonic cells to sub-inhibitory concentrations of antibiotics. When a cell switches to the biofilm mode of growth, it undergoes a phenotypic shift in behavior in which large suites of genes are differentially regulated.

Created with PubMed® Query: biofilm[title] NOT 28392838[PMID] NOT 31293528[PMID] NOT 29372251[PMID] NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

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RevDate: 2021-01-21

Malone M, Radzieta M, Schwarzer S, et al (2021)

Efficacy of a topical concentrated surfactant gel on microbial communities in non-healing diabetic foot ulcers with chronic biofilm infections: A proof-of-concept study.

International wound journal [Epub ahead of print].

This proof-of-concept study sought to determine the effects of standard of care (SOC) and a topically applied concentrated surfactant gel (SG) on the total microbial load, community composition, and community diversity in non-healing diabetic foot ulcers (DFUs) with chronic biofilm infections. SOC was provided in addition to a topical concentrated SG, applied every 2 days for 6 weeks. Wound swabs were obtained from the base of ulcers at baseline (week 0), week 1, mid-point (week 3), and end of treatment (week 6). DNA sequencing and real-time quantitative polymerase chain reaction (qPCR) were employed to determine the total microbial load, community composition, and diversity of patient samples. Tissue specimens were obtained at baseline and scanning electron microscopy and peptide nucleic acid fluorescent in situ hybridisation with confocal laser scanning microscopy were used to confirm the presence of biofilm in all 10 DFUs with suspected chronic biofilm infections. The application of SG resulted in 7 of 10 samples achieving a reduction in mean log10 total microbial load from baseline to end of treatment (0.8 Log10 16S copies, ±0.6), and 3 of 10 samples demonstrated an increase in mean Log10 total microbial load (0.6 log10 16S copies, ±0.8) from baseline to end of treatment. Composition changes in microbial communities were driven by changes to the most dominant bacteria. Corynebacterium sp. and Streptococcus sp. frequently reduced in relative abundance in patient samples from week 0 to week 6 but did not disappear. In contrast, Staphylococcus sp., Finegoldia sp., and Fusobacterium sp., relative abundances frequently increased in patient samples from week 0 to week 6. The application of a concentrated SG resulted in varying shifts to diversity (increase or decrease) between week 0 and week 6 samples at the individual patient level. Any shifts in community diversity were independent to changes in the total microbial loads. SOC and a topical concentrated SG directly affect the microbial loads and community composition of DFUs with chronic biofilm infections.

RevDate: 2021-01-21

Chatterjee B, RR Vittal (2021)

Quorum sensing modulatory and biofilm inhibitory activity of Plectranthus barbatus essential oil: a novel intervention strategy.

Archives of microbiology [Epub ahead of print].

The essential oil (EO) from the roots of Plectranthus barbatus Andr. (Syn. Coleus forskohlii Briq.) was evaluated for quorum sensing (QS) inhibitory activity. P. barbatus EO was screened for inhibition of QS regulated violacein production in Chromobacterium violaceum (ATCC 12472) wild-type strain. At inhibitory (6.25% v/v) and sub-inhibitory concentrations (3.125% v/v) of the EO, dose-dependent response in the inhibition of violacein production was observed in C. violaceum. Similarly, sub-MIC (6.25% v/v) of P. barbatus EO disrupted QS regulated biofilm formation by 27.87% and inhibited swarming and twitching motility in Pseudomonas aeruginosa PA01 implying its anti-infective and QS modulatory activity. Fluorescence microscopy studies confirmed the disruption of biofilm formation by EO in P. aeruginosa PAO1. Promising antibacterial activity was recorded at concentrations as low as 3.12% v/v for Listeria monocytogenes (ATCC 13932) and at 6.25% v/v for both Salmonella enterica subsp. enterica serovar Typhimurium (ATCC 25241) and Escherichia coli (ATCC 11775). Furthermore, significant dose-dependent inhibition was observed for biofilm formation and motility in all the tested pathogens in different treated concentrations. GC-MS analysis revealed α-pinene, endo-borneol, bornyl acetate, 1-Hexyl-2-Nitrocyclohexane as the major phytoconstituents. P. barbatus EO or its constituent compounds with QS modulatory, antimicrobial and biofilm inhibitory property could be potential new-age dietary source based intervention and preservation technologies.

RevDate: 2021-01-20

Santos Carvalhais BE, Souza E Silva C, KV Dos Santos (2021)

Effect of antimicrobials on Stenotrophomonas maltophilia biofilm.

Future microbiology [Epub ahead of print].

Aim: To evaluate the activity of five antimicrobials against young and mature Stenotrophomonas maltophilia biofilms. Materials & methods: Nineteen clinical strains from hemoculture of hemodialysis patients were tested for biofilm kinetics, MIC and minimum biofilm inhibitory concentration (MBIC) in young and mature biofilms. Results: All strains were moderate biofilm producers. MIC showed total susceptibility to levofloxacin and trimethoprim-sulfamethoxazole and partial resistance to ceftazidime (63.2%) and gentamicin (21%). Young and mature biofilms showed the lowest MBIC/MIC ratio for gentamicin, chloramphenicol and levofloxacin, respectively. The highest MBIC/MIC was for trimethoprim-sulfamethoxazole (young) and ceftazidime (mature). Conclusion: Gentamicin displayed surprising activity against S. maltophilia biofilms. Chloramphenicol was indicated as a good option against young S. maltophilia biofilms, and trimethoprim-sulfamethoxazole showed limited antibiofilm activity.

RevDate: 2021-01-20

Yu K, Alzahrani A, Khoddami S, et al (2021)

Self-Limiting Mussel Inspired Thin Antifouling Coating with Broad-Spectrum Resistance to Biofilm Formation to Prevent Catheter-Associated Infection in Mouse and Porcine Models.

Advanced healthcare materials [Epub ahead of print].

Catheter-associated urinary tract infections (CAUTIs) are one of the most commonly occurring hospital-acquired infections. Current coating strategies to prevent catheter-associated biofilm formation are limited by their poor long-term efficiency and limited applicability to diverse materials. Here, the authors report a highly effective non-fouling coating with long-term biofilm prevention activity and is applicable to diverse catheters. The thin coating is lubricous, stable, highly uniform, and shows broad spectrum prevention of biofilm formation of nine different bacterial strains and prevents the migration of bacteria on catheter surface. The coating method is adapted to human-sized catheters (both intraluminal and extraluminal) and demonstrates long-term biofilm prevention activity over 30 days in challenging conditions. The coated catheters are tested in a mouse CAUTI model and demonstrate high efficiency in preventing bacterial colonization of both Gram-positive and Gram-negative bacteria. Furthermore, the coated human-sized Foley catheters are evaluated in a porcine CAUTI model and show consistent efficiency in reducing biofilm formation by Escherichia coli (E. coli) over 95%. The simplicity of the coating method, the ability to apply this coating on diverse materials, and the high efficiency in preventing bacterial adhesion increase the potential of this method for the development of next generation infection resistant medical devices.

RevDate: 2021-01-20

Manoharadas S, Altaf M, Alrefaei AF, et al (2021)

Microscopic analysis of the inhibition of staphylococcal biofilm formation by Escherichia coli and the disruption of preformed staphylococcal biofilm by bacteriophage.

Microscopy research and technique [Epub ahead of print].

The formation of bacterial biofilms is a severely encountered problem in clinical and industrial settings. Most of the naturally occurring bacterial strains are capable of forming mono or mixed biofilms. In this study, we evaluated the potentiality of three clinically relevant species in forming mono and mixed biofilms over glass surface. In addition, we also appraised the efficiency of bacteriophages in alleviating preformed mono and mixed biofilm. Our initial study focused on the ability of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa in forming biofilm on glass cover slip. All the three strains were able to form mono biofilm, although at varying intensities. Interestingly, E. coli inhibited the formation of S. aureus biofilm in a mixed culture. Specific bacteriophages ɸ44AHJD and ɸX174 completely disrupted S. aureus and E. coli preformed biofilm structure after 72 hr of incubation. However, addition of either of the bacteriophage to the mixed E. coli-S. aureus promoted the formation of biofilm by the alternate strain that was not affected by the phage. Our findings elicit the potentiality of common bacterial strains in forming biofilms on smooth glass surface. In addition, these results are very promising for the development of effective drugs using intact bacteriophages for the removal of complicated bacterial biofilms formed in clinically relevant glass surfaces. The observations further complemented the earlier finding of competitive inhibition of S. aureus biofilm development by E. coli.

RevDate: 2021-01-20

Kathwate GH, Shinde RB, S Mohan Karuppayil (2021)

Non-antifungal drugs inhibit growth, morphogenesis and biofilm formation in Candida albicans.

The Journal of antibiotics [Epub ahead of print].

The increased resistance/tolerance of Candida infections to antimicrobial treatment can be attributed to biofilm-associated cells. A way to overcome this situation is to re-purpose non-anti-fungal drugs that could be active against fungi. We have explored the potential of a small library of eighteen non-antifungal drugs used in different human diseases. Candida albicans was cultured in the presence and absence of different concentrations of these drugs. Subsequently, inhibition of growth, germ tube formation, adhesion, and biofilm development were studied. Out of eighteen drug molecules, six showed a reduction in planktonic and biofilm growth in a dose-dependent manner and three drugs inhibited germ tube formation. This study shows the potential of non-antifungal drugs for the development of new anti-Candida agents.

RevDate: 2021-01-20

Keogh RA, Zapf RL, Frey A, et al (2021)

Staphylococcus aureus Trigger Factor is Involved in Biofilm Formation and Cooperates with the Chaperone PpiB.

Journal of bacteriology pii:JB.00681-20 [Epub ahead of print].

Peptidyl-prolyl cis/trans isomerases (PPIases) are enzymes that assist in protein folding around proline-peptide bonds, and often possess chaperone activity. Staphylococcus aureus encodes three PPIases; PrsA, PpiB and Trigger factor (TF). Previous work by our group demonstrated a role for both PrsA and PpiB in S. aureus, however, TF remains largely unstudied. Here, we identify a role for TF in S. aureus biofilm formation, and demonstrate cooperation between TF and the cytoplasmic PPIase PpiB. Mutation of the tig gene (encoding TF) leads to reduced biofilm development in vitro but no significant attenuation of virulence in a mouse model of infection. To investigate if TF possesses chaperone activity, we analyzed the ability of a tig mutant to survive acid and basic stress. While there was no significant decrease in a tig mutant, a ppiB/tig double mutant exhibited a significant decrease in cell viability after acid and base challenge. We then demonstrate that a ppiB/tig double mutant has exacerbated phenotypes in vitro and in vivo when compared to either single mutant. Finally, in vivo immunoprecipitation of epitope tagged PpiB reveals that PpiB interacts with four times the number of proteins when TF is absent from the cell, suggesting it may be compensating for the loss of TF. Interestingly, the only proteins found to interact with TF are TF itself, FnBPB and the chaperone protein ClpB. Collectively, these results support the first phenotype for S. aureus TF and demonstrate a greater network of cooperation between chaperone proteins in Staphylococcus aureusIMPORTANCES. aureus encodes a large number of virulence factors that aid the bacterium in survival and pathogenesis. These virulence factors have a wide variety of functions, however, they must all be properly secreted in order to be functional. Bacterial chaperone proteins often assist in secretion by trafficking proteins to secretion machinery or assisting in proper protein folding. Here, we report that the S. aureus chaperone Trigger factor (TF) contributes to biofilm formation and cooperates with the chaperone PpiB to regulate S. aureus virulence processes. These data highlight the first known role for TF in S. aureus, and suggest that S. aureus chaperone proteins may be involved in a greater regulatory network in the cell.

RevDate: 2021-01-20

Faozia S, Fahmi T, Port GC, et al (2021)

c-di-AMP-regulated K+ importer KtrAB affects biofilm formation, stress response, and SpeB expression in Streptococcus pyogenes.

Infection and immunity pii:IAI.00317-20 [Epub ahead of print].

The second messenger cyclic di-adenosine monophosphate (c-di-AMP) controls biofilm formation, stress response, and virulence in Streptococcus pyogenes The deletion of the c-di-AMP synthase gene, dacA, results in pleiotropic effects including reduced expression of the secreted protease SpeB. Here, we report a role for K+ transport in c-di-AMP-mediated SpeB expression. The deletion of ktrB in the ΔdacA mutant restores SpeB expression. KtrB is a subunit of the K+ transport system KtrAB that forms a putative high-affinity K+ importer. KtrB forms a membrane K+ channel, and KtrA acts as a cytosolic gating protein that controls the transport capacity of the system by binding ligands including c-di-AMP. SpeB induction in ΔdacA by K+ specific ionophore treatment also supports the importance of cellular K+ balance in SpeB production. The double deletion mutant ΔdacAΔktrB not only produces wild type levels of SpeB but also partially or fully reverts the defective ΔdacA phenotypes of biofilm formation and stress responses, suggesting that many ΔdacA phenotypes could be due to cellular K+ imbalance. However, the null pathogenicity of ΔdacA in a murine subcutaneous infection model was not restored by ktrB deletion, suggesting that c-di-AMP controls not only cellular K+ balance but also other metabolic and/or virulence pathways. The deletion of other putative K+ importer genes, kup and kimA, did not phenocopy the deletion of ktrB regarding SpeB induction in ΔdacA, suggesting that KtrAB may be the primary K+ importer that is responsible for controlling cellular K+ levels under lab growth conditions.

RevDate: 2021-01-20

Choonharuangdej S, Srithavaj T, S Thummawanit (2021)

Fungicidal and inhibitory efficacy of cinnamon and lemongrass essential oils on Candida albicans biofilm established on acrylic resin: An in vitro study.

The Journal of prosthetic dentistry pii:S0022-3913(20)30807-6 [Epub ahead of print].

STATEMENT OF PROBLEM: It is unclear whether cinnamon and lemongrass essential oils can effectively reduce the Candida-biofilm frequently formed on dental devices made from heat-polymerized polymethyl methacrylate (PMMA) resin that contributes to the development of mild oropharyngeal as well as life-threatening candidiasis in patients wearing the devices.

PURPOSE: The purpose of this in vitro study was to determine the efficacy of cinnamon and lemongrass essential oils in eradicating Candida albicans biofilm on heat-polymerized PMMA specimens and to determine whether they retard the formation of fungal biofilm.

MATERIAL AND METHODS: The antifungal effect of cinnamon and lemongrass essential oils was determined by using agar disk diffusion and broth microdilution methods to obtain minimum inhibitory concentrations. The mature C albicans biofilm (48 hours) was pre-established on PMMA specimens before being individually treated with various concentrations (½, 1, 2, 4, 8, 16 times minimum inhibitory concentration) of each tested oil for different exposure times (1, 2, 4, 8, and 24 hours). In another experiment, fungal biofilm was established on the PMMA specimens that were primed individually with various concentrations of the tested oils for different times. The 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT)-reduction assay was used to quantitate biofilm viability in both experiments. Statistical analysis was performed by using the 1-sample Kolmogorov-Smirnov test and 2-way ANOVA followed by the Tukey multiple comparison test (α=.05).

RESULTS: Minimum inhibitory concentration values of cinnamon and lemongrass essential oils against planktonic C albicans were 0.1 μL/mL (0.01% v/v) and 0.4 μL/mL (0.04% v/v). At 8 times the minimum inhibitory concentration, cinnamon oil (0.8 μL/mL or 0.08% v/v) and lemongrass oil (3.2 μL/mL or 0.32% v/v) eradicated the pre-established fungal biofilm by 99.0% in an exposure time of 1 hour. In contrast, high concentrations of 8 and 16 times the minimum inhibitory concentration of cinnamon oil (0.8 μL/mL or 0.08% v/v) and lemongrass oil (6.4 μL/mL or 0.64% v/v) coated on PMMA specimens for 24 hours were only able to inhibit the formation of fungal biofilm by approximately 70.0%.

CONCLUSIONS: Cinnamon and lemongrass essential oils can eliminate pre-established C albicans biofilm and restrain the formation of fungal biofilm on heat-polymerized PMMA specimens. Both effects of the tested essential oils depended on dose and exposure or priming time.

RevDate: 2021-01-20

El-Baz AM, Mosbah RA, Goda RM, et al (2021)

Back to Nature: Combating Candida albicans Biofilm, Phospholipase and Hemolysin Using Plant Essential Oils.

Antibiotics (Basel, Switzerland), 10(1): pii:antibiotics10010081.

Candida albicans is the causative agent of fatal systemic candidiasis. Due to limitations of antifungals, new drugs are needed. The anti-virulence effect of plant essential oils (EOs) was evaluated against clinical C. albicans isolates including cinnamon, clove, jasmine and rosemary oils. Biofilm, phospholipase and hemolysin were assessed phenotypically. EOs were evaluated for their anti-virulence activity using phenotypic methods as well as scanning electron microscopy (SEM) and atomic force microscopy (AFM). Among the C. albicans isolates, biofilm, phospholipase and hemolysins were detected in 40.4, 86.5 and 78.8% of isolates, respectively. Jasmine oil showed the highest anti-biofilm activity followed by cinnamon, clove and rosemary oils. SEM and AFM analysis showed reduced adherence and roughness in the presence of EOs. For phospholipase, rosemary oil was the most inhibitory, followed by jasmine, cinnamon and clove oils, and for hemolysins, cinnamon had the highest inhibition followed by jasmine, rosemary and clove oils. A molecular docking study revealed major EO constituents as promising inhibitors of the Als3 adhesive protein, with the highest binding for eugenol, followed by 1,8-cineole, 2-phenylthiolane and cinnamaldehyde. In conclusion, EOs have a promising inhibitory impact on Candida biofilm, phospholipase and hemolysin production, hence EOs could be used as potential antifungals that impact virulence factors.

RevDate: 2021-01-20

Oliveira VC, Macedo AP, Melo LDR, et al (2021)

Bacteriophage Cocktail-Mediated Inhibition of Pseudomonas aeruginosa Biofilm on Endotracheal Tube Surface.

Antibiotics (Basel, Switzerland), 10(1): pii:antibiotics10010078.

Although different strategies to control biofilm formation on endotracheal tubes have been proposed, there are scarce scientific data on applying phages for both removing and preventing Pseudomonas aeruginosa biofilms on the device surface. Here, the anti-biofilm capacity of five bacteriophages was evaluated by a high content screening assay. We observed that biofilms were significantly reduced after phage treatment, especially in multidrug-resistant strains. Considering the anti-biofilm screens, two phages were selected as cocktail components, and the cocktail's ability to prevent colonization of the endotracheal tube surface was tested in a dynamic biofilm model. Phage-coated tubes were challenged with different P. aeruginosa strains. The biofilm growth was monitored from 24 to 168 h by colony forming unit counting, metabolic activity assessment, and biofilm morphology observation. The phage cocktail promoted differences of bacterial colonization; nonetheless, the action was strain dependent. Phage cocktail coating did not promote substantial changes in metabolic activity. Scanning electron microscopy revealed a higher concentration of biofilm cells in control, while tower-like structures could be observed on phage cocktail-coated tubes. These results demonstrate that with the development of new coating strategies, phage therapy has potential in controlling the endotracheal tube-associated biofilm.

RevDate: 2021-01-20

Zheng Y, Wang D, LZ Ma (2021)

Effect of Polyhexamethylene Biguanide in Combination with Undecylenamidopropyl Betaine or PslG on Biofilm Clearance.

International journal of molecular sciences, 22(2): pii:ijms22020768.

Hospital-acquired infection is a great challenge for clinical treatment due to pathogens' biofilm formation and their antibiotic resistance. Here, we investigate the effect of antiseptic agent polyhexamethylene biguanide (PHMB) and undecylenamidopropyl betaine (UB) against biofilms of four pathogens that are often found in hospitals, including Gram-negative bacteria Pseudomonas aeruginosa and Escherichia coli, Gram-positive bacteria Staphylococcus aureus, and pathogenic fungus, Candida albicans. We show that 0.02% PHMB, which is 10-fold lower than the concentration of commercial products, has a strong inhibitory effect on the growth, initial attachment, and biofilm formation of all tested pathogens. PHMB can also disrupt the preformed biofilms of these pathogens. In contrast, 0.1% UB exhibits a mild inhibitory effect on biofilm formation of the four pathogens. This concentration inhibits the growth of S. aureus and C. albicans yet has no growth effect on P. aeruginosa or E. coli. UB only slightly enhances the anti-biofilm efficacy of PHMB on P. aeruginosa biofilms. However, pretreatment with PslG, a glycosyl hydrolase that can efficiently inhibit and disrupt P. aeruginosa biofilm, highly enhances the clearance effect of PHMB on P. aeruginosa biofilms. Meanwhile, PslG can also disassemble the preformed biofilms of the other three pathogens within 30 min to a similar extent as UB treatment for 24 h.

RevDate: 2021-01-20

Maione A, de Alteriis E, Carraturo F, et al (2021)

The Membranotropic Peptide gH625 to Combat Mixed Candida albicans/Klebsiella pneumoniae Biofilm: Correlation between In Vitro Anti-Biofilm Activity and In Vivo Antimicrobial Protection.

Journal of fungi (Basel, Switzerland), 7(1): pii:jof7010026.

The antibiofilm activity of a gH625 analogue was investigated to determine the in vitro inhibition and eradication of a dual-species biofilm of Candida albicans and Klebsiella pneumoniae, two leading opportunistic pathogens responsible for several resistant infections. The possibility of effectively exploiting this peptide as an alternative anti-biofilm strategy in vivo was assessed by the investigation of its efficacy on the Galleria mellonella larvae model. Results on larvae survival demonstrate a prophylactic efficacy of the peptide towards the infection of each single microorganism but mainly towards the co-infection. The expression of biofilm-related genes in vivo showed a possible synergy in virulence when these two species co-exist in the host, which was effectively prevented by the peptide. These findings provide novel insights into the treatment of medically relevant bacterial-fungal interaction.

RevDate: 2021-01-20

Souissi M, Ben Lagha A, Chaieb K, et al (2021)

Effect of a Berry Polyphenolic Fraction on Biofilm Formation, Adherence Properties and Gene Expression of Streptococcus mutans and Its Biocompatibility with Oral Epithelial Cells.

Antibiotics (Basel, Switzerland), 10(1): pii:antibiotics10010046.

The ability of Streptococcus mutans to adhere to oral surfaces and form biofilm is a key step in the tooth decay process. The aim of this study was to investigate a berry (wild blueberry, cranberry, and strawberry) polyphenolic fraction, commercialized as Orophenol®, for its antibacterial, anti-biofilm, and anti-adhesion properties on S. mutans. Moreover, the biocompatibility of the fraction with human oral epithelial cells was assessed. Phenolic acids, flavonoids (flavonols, anthocyanins, flavan-3-ols), and procyanidins made up 10.71%, 19.76%, and 5.29% of the berry polyphenolic fraction, respectively, as determined by chromatography and mass spectrometry. The berry polyphenolic preparation dose-dependently inhibited S. mutans biofilm formation while not reducing bacterial growth. At concentrations ranging from 250 to 1000 µg/mL, the fraction inhibited the adhesion of S. mutans to both saliva-coated hydroxyapatite and saliva-coated nickel-chrome alloy. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis showed that incubating S. mutans with the berry polyphenolic fraction was associated with a reduced expression of luxS gene, which regulates quorum sensing in S. mutans. The berry fraction did not show any significant cytotoxicity in an oral epithelial cell model. In conclusion, Orophenol®, which is a mixture of polyphenols from wild blueberry, cranberry and strawberry, possesses interesting anti-caries properties while being compatible with oral epithelial cells.

RevDate: 2021-01-20

Nesse LL, Mo SS, Ramstad SN, et al (2021)

The Effect of Antimicrobial Resistance Plasmids Carrying blaCMY-2 on Biofilm Formation by Escherichia coli from the Broiler Production Chain.

Microorganisms, 9(1): pii:microorganisms9010104.

Extended-spectrum cephalosporin-resistant Escherichia coli (ESCR E. coli) with plasmids carrying the blaCMY-2 resistance gene have been isolated from the Norwegian broiler production chain through the Norwegian monitoring program for antimicrobial resistance in animals, food and feed, NORM-VET. The aim of the present study was to investigate the biofilm forming abilities of these strains, and in particular to see whether these might be influenced by the carriage of blaCMY-2 plasmids. The ESCR E. coli from the broiler production chain displayed relatively low biofilm forming abilities in the crystal violet biofilm assay as compared to quinolone-resistant E. coli (QREC) from the same population (mean ± SD = 0.686 ± 0.686 vs. 1.439 ± 0.933, respectively). Acquisition of two different blaCMY-2 plasmids by QREC strains reduced their biofilm production in microtiter plates, but not their biofilm production on Congo Red agar plates. Furthermore, motility was reduced, but not planktonic growth. We hypothesize that genes carried by these plasmids may have caused the observed reduction in biofilm formation, possibly mediated through changes in flagellar expression or function. Furthermore, this may help explain the different biofilm forming abilities observed between ESCR E. coli and QREC. The results also indicate that the risk of biofilm reservoirs of antimicrobial resistant E. coli on in the broiler production is lower for ESCR E. coli than for QREC.

RevDate: 2021-01-20

Dasgupta Q, Madras G, K Chatterjee (2017)

Controlled Release of Usnic Acid from Biodegradable Polyesters to Inhibit Biofilm Formation.

ACS biomaterials science & engineering, 3(3):291-303.

Controlled and sustained release of antibacterial drugs is a promising approach to address challenges related to bacterial infections in biomedical implants. Biocompatible polyols like xylitol and mannitol are frequently used to synthesize cross-linked, biodegradable polyesters. Xylitol-based adipoyl and sebacoyl polyesters were synthesized by a catalyst free melt polyesterification technique. Unlike traditional drug delivery systems, the objective of this work was to develop biodegradable polymers with usnic acid (UA), a known antibacterial agent, entrapped in the polymer network. Apart from offering a wider control of the release kinetics and improved processability, the hydrolytic degradation results in the concomitant resorption of the polymer. Polymer properties such as degradation, modulus, and drug release were tuned through a subtle change in the chain length of the diacid. In 1 week, the xylitol based adipoyl ester degrades 41% and releases 25% of its initial drug loading whereas the sebacoyl ester degrades 23% in and releases 9% of the loaded drug. A kinetic model has been used to understand the UA release profiles and determine degradation and release parameters that influence release from the polymers. These polyesters are cytocompatible and exhibit excellent bactericidal activity against Staphyloccus aureus by inducing oxidative stress. This work enables a strategy to synthesize biodegradable polymers for potential to inhibit biofilm formation in vivo with tunable mechanical and degradation properties, and variable controlled release.

RevDate: 2021-01-19

Zhou L, Zhao B, Ou P, et al (2021)

Core nitrogen cycle of biofoulant in full-scale anoxic & oxic biofilm-membrane bioreactors treating textile wastewater.

Bioresource technology, 325:124667 pii:S0960-8524(21)00005-5 [Epub ahead of print].

Core nitrogen cycle within biofoulant in full-scale anoxic & oxic biofilm-membrane bioreactor (bMBR) treating textile wastewater was investigated. Wastewater filtered through membrane with biofoulant had elevated NH4+-N and NO2--N concentrations corresponding to decreased NO3--N concentrations. Nevertheless, total nitrogen concentrations did not change significantly, indicating negligible nitrogen removal activities within biofoulant. Metagenomic analysis revealed a lack of genes, such as AmoCAB and Hao in biofoulant, indicating absence of nitrification or anammox populations. However, genes encoding complete pathway for dissimilatory nitrate reduction to ammonium (DNRA) were discovered in 15 species that also carry genes encoding both nitrate reductase and nitrite reductase. No specie contained all genes for complete denitrification pathway. High temperature, high C:N ratio, and anoxic conditions of textile wastewater could favorite microbes growth with DNRA pathway over those with canonical denitrification pathway. High dissolved oxygen concentrations could effectively inhibit DNRA to minimize ammonia concentration in the effluent.

RevDate: 2021-01-19

Pirhanov A, Bridges CM, Goodwin RA, et al (2021)

Optogenetics in Sinorhizobium meliloti Enables Spatial Control of Exopolysaccharide Production and Biofilm Structure.

ACS synthetic biology [Epub ahead of print].

Microorganisms play a vital role in shaping the soil environment and enhancing plant growth by interacting with plant root systems. Because of the vast diversity of cell types involved, combined with dynamic and spatial heterogeneity, identifying the causal contribution of a defined factor, such as a microbial exopolysaccharide (EPS), remains elusive. Synthetic approaches that enable orthogonal control of microbial pathways are a promising means to dissect such complexity. Here we report the implementation of a synthetic, light-activated, transcriptional control platform using the blue-light responsive DNA binding protein EL222 in the nitrogen fixing soil bacterium Sinorhizobium meliloti. By fine-tuning the system, we successfully achieved optical control of an EPS production pathway without significant basal expression under noninducing (dark) conditions. Optical control of EPS recapitulated important behaviors such as a mucoid plate phenotype and formation of structured biofilms, enabling spatial control of biofilm structures in S. meliloti. The successful implementation of optically controlled gene expression in S. meliloti enables systematic investigation of how genotype and microenvironmental factors together shape phenotype in situ.

RevDate: 2021-01-19

Devaraj A, González JF, Eichar B, et al (2021)

Enhanced biofilm and extracellular matrix production by chronic carriage versus acute isolates of Salmonella Typhi.

PLoS pathogens, 17(1):e1009209 pii:PPATHOGENS-D-20-02247.

Salmonella Typhi is the primary causative agent of typhoid fever; an acute systemic infection that leads to chronic carriage in 3-5% of individuals. Chronic carriers are asymptomatic, difficult to treat and serve as reservoirs for typhoid outbreaks. Understanding the factors that contribute to chronic carriage is key to development of novel therapies to effectively resolve typhoid fever. Herein, although we observed no distinct clustering of chronic carriage isolates via phylogenetic analysis, we demonstrated that chronic isolates were phenotypically distinct from acute infection isolates. Chronic carriage isolates formed significantly thicker biofilms with greater biomass that correlated with significantly higher relative levels of extracellular DNA (eDNA) and DNABII proteins than biofilms formed by acute infection isolates. Importantly, extracellular DNABII proteins include integration host factor (IHF) and histone-like protein (HU) that are critical to the structural integrity of bacterial biofilms. In this study, we demonstrated that the biofilm formed by a chronic carriage isolate in vitro, was susceptible to disruption by a specific antibody against DNABII proteins, a successful first step in the development of a therapeutic to resolve chronic carriage.

RevDate: 2021-01-19

Xie Y, Zhang M, Zhang W, et al (2020)

Gold Nanoclusters-Coated Orthodontic Devices Can Inhibit the Formation of Streptococcus mutans Biofilm.

ACS biomaterials science & engineering, 6(2):1239-1246.

Oral health is an issue that has attracted increasing attention recently. Poor oral hygiene may induce the formation of oral biofilm on orthodontic devices, and cause gingivitis and dental caries. Here, we present a strategy for modifying orthodontic devices (e.g., invisalign aligner) with quaternary ammonium (QA)-modified gold nanoclusters (QA-GNCs) as an antibiotic reagent to prevent bacterial contamination and biofilm formation. The QA-GNCs-coated aligner can efficiently inhibit the adhesion of cariogenic pathogenic Streptococcus mutans and the formation of biofilm. Moreover, the antibacterial activity of the coated QA-GNCs can be maintained for at least 3 months and after repeated usage (>3 cycles). Furthermore, the QA-GNCs coating shows excellent biosafety confirmed by the cell viability test, the hemolysis assay, and animal experiments. Our strategy for antibacterial coating has the advantages of broad applications, low cost, good stability, high antibacterial efficiency, good biocompatibility, and low risk of antibiotic contamination, which could be particularly useful in preventing infections involving implantable medical devices or wearable electronics.

RevDate: 2021-01-19

Nascimento GG, Leite FRM, Pennisi PRC, et al (2021)

Use of air polishing for supra- and subgingival biofilm removal for treatment of residual periodontal pockets and supportive periodontal care: a systematic review.

Clinical oral investigations [Epub ahead of print].

AIM: To systematically review the literature to compare the efficacy of air polishing to hand or ultrasonic instrumentation to reduce periodontal inflammation during treatment of residual pockets or supportive periodontal care.

METHODS: Electronic searches were performed in five different databases, and two databases were used to capture the "grey literature partially." Clinical trials that compared the use of an air-polishing device to either conventional scaling and root planing (hand and/or ultrasonic instrumentation) or no treatment during periodontal therapy were included without restriction of year and publication status. The Joanna Briggs Institute instrument for clinical trials was used to appraise the studies critically. The results were submitted to qualitative descriptive analysis. The systematic review protocol was registered in PROSPERO (CRD420220156176).

RESULTS: Electronic searches found 1100 hits published between 2008 and 2019. Thirteen studies were included in the review, out of which four had a follow-up longer than 180 days. Results indicated no differences between the efficacy of air polishing and hand or ultrasonic instruments to reduce periodontal inflammation.

CONCLUSIONS: Our findings suggest that there is no difference in the efficacy of air polishing and hand or ultrasonic instrumentation to control biofilm and reduce periodontal inflammation. However, these findings must be carefully interpreted owing to methodological issues, including a short follow-up, and a potential conflict of interest related to industry funding.

CLINICAL RELEVANCE: Air polishing for biofilm control may be used as an alternative to hand and ultrasonic instrumentation to reduce periodontal inflammation during treatment of residual pockets or supportive periodontal care.

RevDate: 2021-01-19

Quan K, Zhang Z, Ren Y, et al (2020)

Homogeneous Distribution of Magnetic, Antimicrobial-Carrying Nanoparticles through an Infectious Biofilm Enhances Biofilm-Killing Efficacy.

ACS biomaterials science & engineering, 6(1):205-212.

Magnetic, antimicrobial-carrying nanoparticles provide a promising, new and direly needed antimicrobial strategy against infectious bacterial biofilms. Penetration and accumulation of antimicrobials over the thickness of a biofilm is a conditio sine qua non for effective killing of biofilm inhabitants. Simplified schematics on magnetic-targeting always picture homogeneous distribution of magnetic, antimicrobial-carrying nanoparticles over the thickness of biofilms, but this is not easy to achieve. Here, gentamicin-carrying magnetic nanoparticles (MNPs-G) were synthesized through gentamicin conjugation with iron-oxide nanoparticles and used to demonstrate the importance of their homogeneous distribution over the thickness of a biofilm. Diameters of MNPs-G were around 60 nm, well below the limit for reticuloendothelial rejection. MNPs-G killed most ESKAPE-panel pathogens, including Escherichia coli, equally as well as gentamicin in solution. MNPs-G distribution in a Staphylococcus aureus biofilm was dependent on magnetic-field exposure time and most homogeneous after 5 min magnetic-field exposure. Exposure of biofilms to MNPs-G with 5 min magnetic-field exposure yielded not only homogeneous distribution of MNPs-G, but concurrently better staphylococcal killing at all depths than that of MNPs, gentamicin in solution, and MNPs-G, or after other magnet-field exposure times. In summary, homogeneous distribution of gentamicin-carrying magnetic nanoparticles over the thickness of a staphylococcal biofilm was essential for killing biofilm inhabitants and required optimizing of the magnetic-field exposure time. This conclusion is important for further successful development of magnetic, antimicrobial-carrying nanoparticles toward clinical application.

RevDate: 2021-01-19

Al-Maqtari QA, Al-Ansi W, Mahdi AA, et al (2021)

Supercritical fluid extraction of four aromatic herbs and assessment of the volatile compositions, bioactive compounds, antibacterial, and anti-biofilm activity.

Environmental science and pollution research international [Epub ahead of print].

Artemisia arborescens, Artemisia abyssinica, Pulicaria jaubertii, and Pulicaria petiolaris are fragrant herbs traditionally used in medication and as a food seasoning. To date, there are no studies on the use of supercritical fluids extraction with carbon dioxide (SFE-CO2) on these plants. This study evaluates and compares total phenolic content (TPC), antioxidant activity by DPPH• and ABTS•+, antibacterial, and anti-biofilm activities of SFE-CO2 extracts. Extraction was done by SFE-CO2 with 10% ethanol as a co-solvent. A. abyssinica extract had the highest extraction yield (8.9% ± 0.41). The GC/MS analysis of volatile compounds identified 307, 265, 213, and 201compounds in A. abyssinica, A. arborescens, P. jaubertii, and P. petiolaris, respectively. The P. jaubertii extract had the highest TPC (662.46 ± 50.93 mg gallic acid equivalent/g dry extract), antioxidant activity (58.98% ± 0.20), and antioxidant capacity (71.78 ± 1.84 mg Trolox equivalent/g dry extract). The A. abyssinica and P. jaubertii extracts had significantly higher antimicrobial activity and were more effective against Gram-positive bacteria. B. subtilis was the most sensitive bacterium. P. aeruginosa was the most resistant bacterium. P. jaubertii extract had the optimum MIC and MBC (0.4 mg/ml) against B. subtilis. All SFE-CO2 extracts were effective as an anti-biofilm formation for all tested bacteria at 1/2 MIC. Meanwhile, P. jaubertii and P. petiolaris extracts were effective anti-biofilm for most tested bacteria at 1/16 MIC. Overall, the results indicated that the SFE-CO2 extracts of these plants are good sources of TPC, antioxidants, and antibacterial, and they have promising applications in the industrial fields.

RevDate: 2021-01-17

Guo R, Luo X, Liu J, et al (2021)

Mass spectrometry based targeted metabolomics precisely characterized new functional metabolites that regulate biofilm formation in Escherichia coli.

Analytica chimica acta, 1145:26-36.

Biofilms are broadly formed by diverse microorganisms under stressful environments that are basically surrounded by an EPS matrix, which enable bacterial cells to confer the resistance to the biocides, antibiotics and other invasions. Yet, biofilms cause harmful impacts in various fields, including clinical infections, food contaminations and environmental pollution. However, the mechanism of biofilm formation remains incompletely elucidated, and currently, we lack an efficient strategy to tackle these tough problems by eradicating biofilms. In the present study, we sought to decipher the mechanism of biofilm formation in Escherichia coli from metabolic perspective. By exposing bacterial cells to various concentrations of iron, we found that iron can regulate biofilm formation, and the phenotypic changes were obviously dependent on iron concentration. A functional metabolome assay was further implemented to investigate the regulatory mechanism of iron on biofilm formation; we verified that siderophores mostly account for the transportation of iron into bacterial cells. Then, the bioavailable iron was recruited by bacterial cells to direct the levels of five functional metabolites (l-tryptophan, 5'-MTA, spermidine, CMP and L-leucine), which were identified as new effectors that directly regulate biofilm formation. Taken together, this study is the first to identify five functional metabolites to efficiently regulate biofilm formation, which can be targeted to tackle the harmful impacts associated with biofilm formation in different niches.

RevDate: 2021-01-18

Meena H, Mishra R, Ranganathan S, et al (2021)

Attenuation of quorum sensing mediated virulence factors production and biofilm formation in Pseudomonas aeruginosa PAO1 by Colletotrichum gloeosporioides.

Microbial pathogenesis pii:S0882-4010(20)31089-5 [Epub ahead of print].

Signal dependent microbial communication in Pseudomonas aeruginosa PAO1 is a typical phenomenon mediated by acyl homo-serine lactone molecules that helps in developing biofilm and enhance antibiotic resistance. Microbial sources provide insight to the hidden treasure of secondary metabolites, and these structurally diversified chemical motifs can be used as antimicrobial and anti-infective agents. In the present study, endophytic fungus, Colletotrichum gloeosporioides isolated from Carica papaya leaves explored for anti-infective potential against P. aeruginosa PAO1. The crude extract of C. gloeosporioides displayed bacteriostatic effect on P. aeruginosa PAO1 growth at 750 μg/ml concentration. A significant decline was observed in the production of quorum sensing regulated virulence factors, i.e. 56.32%, 62.54%, and 66.67% of pyocyanin, chitinase, and elastase enzyme, respectively. A drastic reduction in pathogenic determinant behaviour after treatment with crude extract of C. gloeosporioides i.e. EPS, rhamnolipid, and HCN production was noted. Light microscopy and CLSM analysis revealed that fungal extract treatment has reduced bacterial ability to form dense biofilm architecture. In silico analysis demonstrated the binding efficiency of bioactive compound, 4-(2,3-dimethoxybenzylidene)-3-methyl-1-(4-nitrophenyl)-2-pyrazolin-5-one, which is equipotent to the natural ligand and displayed a docking score of -5.436 kcal/mol with QS transcriptional regulator (LasR). Whereas the compound Acetamide, n-[tetrahydro-3-(phenylmethyl) thieno [3,4-d]thiazol-2 (3 h)-ylidene]-, s,s-dioxide exhibits a docking score of -4.088 kcal/mol (LasR) and -1.868 kcal/mol (RhlR) with cognate receptor proteins. Henceforth, the research report suggests C. gloeosporioides derived metabolites could be considered as a potential inhibitors of QS regulated virulence factors and biofilm production in P. aeruginosa PAO1.

RevDate: 2021-01-18

Raouf M, Essa S, El Achy S, et al (2021)

Evaluation of Combined Ciprofloxacin and Azithromycin Free and Nano formulations to control Biofilm producing Pseudomonas aeruginosa isolated from burn wounds.

Indian journal of medical microbiology pii:S0255-0857(21)00004-9 [Epub ahead of print].

BACKGROUND: Nanoparticles are becoming increasingly important against resistant superbugs including Pseudomonas aeruginosa infections.

AIMS: Exploration of Azithromycin as an adjunctive therapy to Ciprofloxacin for treatment of P. aeruginosa infections. Also, preparation of Ciprofloxacin-Azithromycin nanoparticles on chitosan nanocarrier (Cipro-AZM-CS) and assessment of its antimicrobial effect in vitro and in vivo.

METHODS: Detection of biofilm production and biofilm-specific antibiotic resistance ndvB and tssC1 genes was attempted. Minimal inhibitory concentration (MIC) and Minimum biofilm eradication concentration (MBEC) were done in vitro for assessment of P. aeruginosa planktonic and biofilm forms eradication, respectively. In In vivo study, Cipro-AZM-CS and free form were used to evaluate survival rate, wound contraction and bacterial load in mice after third degree burn.

RESULTS: All isolates were positive for biofilm production and ndvB and tssC1 genes. Majority of isolates (37, 74%) were extensively drug resistant. In the planktonic state, MIC values of Cipro-AZM free and CS forms were significantly lower than free Cipro MIC (P=0.015 and P<0.001 respectively). Also, Cipro-AZM free and CS MBEC values were significantly lower than that of free Cipro (P <0.010 and P<0.001 respectively). Furthermore, The MIC and MBEC values of free Cipro-AZM decreased significantly when challenged with Cipro-AZM-CS (P=0.009 and P<0.001 respectively). In vivo study combined free and Cipro-AZM-CS treated subgroups showed 100% mice survival with early resolution of infection and wound contraction (75%, 77.5 % respectively) VS 45% for Cipro CS (P<0.001).

CONCLUSION: Combined free and Cipro-AZM-CS showed promising results in vitro and in vivo overcoming high resistance of biofilm producing P. aeruginosa.

RevDate: 2021-01-18

Sundaramoorthy M, Karuppaiah A, Nithyanth M, et al (2021)

Formulation development of cream with mupirocin and essential oils for eradication of biofilm mediated antimicrobial resistance.

Archives of microbiology [Epub ahead of print].

Staphylococcus aureus (S.aureus) is both a colonizer as well as a human pathogen that causes a variety of diseases. Mupirocin is a topical antimicrobial agent which is very effective against S.aureus infection. However, treating the S.aureus infection using mupirocin could be complicated due to biofilm formation. Consequently, resistance to mupirocin occurs and leads to chronic infection. The combination of mupirocin with a compound that has biofilm eradicating effect would be an ideal solution for effectively treating biofilm infections. Therefore, in this study, we have investigated the biofilm inhibitory and eradication effect of mupirocin with three essential oils (Cinnamon Oil (CO), Eugenol (EU) and Eucalyptus Oil (EO)) against sessile S.aureus. From these preliminary results, it was found that the mupirocin-CO (0.2 µg/ml-5.218 mg/ml) combination has a better synergistic antibiofilm effect against sessile S.aureus and the fractional inhibitory concentration index was found to be 0.458. The best combination of mupirocin with CO was loaded into a non-greasy O/W cream. The physico-chemical and microbiological evaluations were carried out for the prepared cream. The prepared cream has better biofilm eradication activity (40%) when compared to a marketed cream (20%).

RevDate: 2021-01-18

Di Marco NI, Páez PL, Lucero-Estrada CSM, et al (2021)

Naphthoquinones inhibit formation and viability of Yersinia enterocolitica biofilm.

World journal of microbiology & biotechnology, 37(2):30.

The capacity of different naphthoquinones to inhibit and eradicate Yersinia enterocolitica biofilm was investigated and possible mechanisms of action were evaluated. Inhibition of biofilm formation and cell viability, quorum sensing (QS) inhibition and oxidative stress generation of 23 naphthoquinones were assayed against Yersinia enterocolitica. The best anti-biofilm agents at 100 µmol l-1 were compounds 3, 11 and 13, which showed biofilm inhibition higher than 75%. Compound 3 was the most effective against biofilm forming capacity of Y. enterocolitica WAP 314 with a minimum biofilm inhibitory concentration (MBIC) of 25 µmol l-1; while against Y. enterocolitica CLC001, the lowest MBIC was 6.1 µmol l-1 for compound 11. Acyl-homoserine lactones production was decreased with compound 13. We showed that the oxidative stress influence biofilm growth, by means of ROS and RNI increment. All treatments increased ROS and RNI values in the biofilm of both strains; while in planktonic cells, the increase was lesser. Additionally, Y. enterocolitica WAP 314 biofilm treated with compounds 11 and 13 showed above 80% of SOD consumption. In Y. enterocolitica CLC001 biofilm all compounds induced above 90% of SOD consumption. The SOD activity was higher in biofilm than in planktonic cells. In conclusion, this is the first study to demonstrate that naphthoquinones are able to inhibit biofilm formation of Y. enterocolitica without critical disturbing its planktonic growth. Naphthoquinones as anti-biofilm agents might potentially be useful in the treatment of biofilm-associated infections in the future.

RevDate: 2021-01-19

Chen J, Chen Z, Yuan K, et al (2020)

Recombinant bacteriophage T4 Rnl1 impacts Streptococcus mutans biofilm formation.

Journal of oral microbiology, 13(1):1860398.

Bacteriophage T4 RNA ligase 1 (T4 Rnl1) can be stably expressed in many bacteria and has been reported to affect the bioactivity of the host bacteria. Recently, we constructed bacteriophage T4 Rnl1 expressing system in Streptococcus mutans, a crucial biofilm-forming and dental caries-causing oral pathogen. Here, we characterized the function of recombinant bacteriophage T4 Rnl1 in biofilm formation of S. mutans. The T4 Rnl1 mutant exhibited similar growth phenotype but resulted in a significant reduction of biofilm biomass compared to wild type strain and empty plasmid carrying strain. The abnormal biofilm of the T4 Rnl1 mutant harbored loose bacterial clusters with defective production and distribution of exopolysaccharides. Moreover, the expression of several biofilm formation-associated genes was dysregulated at mRNA level in the T4 Rnl1 mutant. These results reveal that the bacteriophage T4 Rnl1 exert antibiofilm activities against the cariogenic bacterium S. mutans, which impacts the spatial organization of the exopolysaccharides and further impairs the three-dimensional biofilm architecture. These findings implicate that manipulation of bacteriophage T4 Rnl1, a biological tool used for RNA ligation, will provide a promising approach to cariogenic biofilm control.

RevDate: 2021-01-16

Nejadmansouri M, Razmjooei M, Safdarianghomsheh R, et al (2021)

Semi-continuous production of xanthan in biofilm reactor using Xanthomonas campestris.

Journal of biotechnology pii:S0168-1656(21)00013-4 [Epub ahead of print].

Semi-continuous production of xanthan gum using self-immobilized Xanthomonas campestris cells in biofilm reactors was studied. Fermentation was carried out using two different designs of biofilm reactor equipped with a) stainless-steel support (SSS) and b) polyethylene support (PES). Fermentation was performed in three cycles with refreshing the media at the beginning of each: cycle 1, 0-27 h; cycle 2, 27-54 h; and cycle 3, 54-78.5 h. Results showed that the glucose consumption and the pH reduction in the PES biofilm reactor was faster compared to the SSS biofilm reactor. Scanning electron microscopy showed that the SSS was capable to immobilize more cells during the growth of X. campestris. The maximum concentration of xanthan gum in the SSS biofilm reactor obtained after 27 h (3.47 ± 0.71 g/L), while the maximum concentration of xanthan in the PES biofilm reactor obtained after 78.5 h (3.21 ± 0.68 g/L). Thermal stability analysis of xanthan using differential scanning calorimetry showed the presence of two fractures attributed to dehydration and degradation of polymer. The thermogram represented both endothermal and exothermal behaviour of xanthan polymer. Furthermore, the functional groups and molecular structure of the xanthan produced in this study was evaluated using Fourier transform infrared spectrometry and also proton nuclear magnetic resonance. in addition, the surface tension of (0.2%, w/v) xanthan gum solution was in a range of 52.16-56.5 mN/m. Rheological analysis of xanthan showed that the G' values were higher than the G″ in all frequencies demonstrating a relatively high elasticity of the produced xanthan gum.

RevDate: 2021-01-16

Maszewska A, Moryl M, Wu J, et al (2021)

Amikacin and bacteriophage treatment modulates outer membrane proteins composition in Proteus mirabilis biofilm.

Scientific reports, 11(1):1522.

Modification of outer membrane proteins (OMPs) is the first line of Gram-negative bacteria defence against antimicrobials. Here we point to Proteus mirabilis OMPs and their role in antibiotic and phage resistance. Protein profiles of amikacin (AMKrsv), phage (Brsv) and amikacin/phage (AMK/Brsv) resistant variants of P. mirabilis were compared to that obtained for a wild strain. In resistant variants there were identified 14, 1, 5 overexpressed and 13, 5, 1 downregulated proteins for AMKrsv, Brsv and AMK/Brsv, respectively. Application of phages with amikacin led to reducing the number of up- and downregulated proteins compared to single antibiotic treatment. Proteins isolated in AMKrsv are involved in protein biosynthesis, transcription and signal transduction, which correspond to well-known mechanisms of bacteria resistance to aminoglycosides. In isolated OMPs several cytoplasmic proteins, important in antibiotic resistance, were identified, probably as a result of environmental stress, e.g. elongation factor Tu, asparaginyl-tRNA and aspartyl-tRNA synthetases. In Brsv there were identified: NusA and dynamin superfamily protein which could play a role in bacteriophage resistance. In the resistant variants proteins associated with resistance mechanisms occurring in biofilm, e.g. polyphosphate kinase, flagella basal body rod protein were detected. These results indicate proteins important in the development of P. mirabilis antibiofilm therapies.

RevDate: 2021-01-16

Park HY, Zoller SD, Hegde V, et al (2021)

Comparison of two fluorescent probes in preclinical non-invasive imaging and image-guided debridement surgery of Staphylococcal biofilm implant infections.

Scientific reports, 11(1):1622.

Implant-associated infections are challenging to diagnose and treat. Fluorescent probes have been heralded as a technologic advancement that can improve our ability to non-invasively identify infecting organisms, as well as guide the inexact procedure of surgical debridement. This study's purpose was to compare two fluorescent probes for their ability to localize Staphylococcus aureus biofilm infections on spinal implants utilizing noninvasive optical imaging, then assessing the broader applicability of the more successful probe in other infection animal models. This was followed by real-time, fluorescence image-guided surgery to facilitate debridement of infected tissue. The two probe candidates, a labelled antibiotic that targets peptidoglycan (Vanco-800CW), and the other, a labelled antibody targeting the immunodominant Staphylococcal antigen A (1D9-680), were injected into mice with spine implant infections. Mice were then imaged noninvasively with near infrared fluorescent imaging at wavelengths corresponding to the two probe candidates. Both probes localized to the infection, with the 1D9-680 probe showing greater fidelity over time. The 1D9-680 probe was then tested in mouse models of shoulder implant and allograft infection, demonstrating its broader applicability. Finally, an image-guided surgery system which superimposes fluorescent signals over analog, real-time, tissue images was employed to facilitate debridement of fluorescent-labelled bacteria.

RevDate: 2021-01-16

Havlena Z, Kieft TL, Veni G, et al (2021)

Lighting effects on the development and diversity of photosynthetic biofilm communities in Carlsbad Cavern, New Mexico.

Applied and environmental microbiology pii:AEM.02695-20 [Epub ahead of print].

Photosynthetic cave communities ("lampenflora") proliferate in Carlsbad Cavern and other show caves worldwide due to artificial lighting. These biofilms mar the aesthetics and can degrade underlying cave surfaces. The National Park Service recently modernized the lighting in Carlsbad Cavern to an LED system that allows adjustment of color temperature and intensity. We hypothesized that lowering the color temperature would reduce photopigment development. We therefore assessed lampenflora responses to changes in lighting by monitoring photosynthetic communities over the course of a year. We measured photopigments using reflected light spectrophotometric observations and analyzed microbial community composition with 16S and 18S rRNA gene amplicon sequencing. Reflected light spectrophotometry revealed that photosynthetic biofilm development is affected by lighting intensity, color temperature, substrate type, and cleaning of the substrate. Gene sequencing showed that the most abundant phototrophs were Cyanobacteria and members of the algal phyla Chlorophyta and Ochrophyta At the end of the study, visible growth of lampenflora was seen at all sites. At sites that had no established biofilm at the start of the study period, Cyanobacteria became abundant and outpaced an increase in eukaryotic algae. Microbial diversity also increased over time at these sites, suggesting a possible pattern of early colonization and succession. Bacterial community structure showed significant effects of all variables: color temperature, light intensity, substrate type, site, and previous cleaning of the substrate. These findings provide fundamental information that can inform management practices; they suggest that altering lighting conditions alone may be insufficient to prevent lampenflora growth.IMPORTANCE Artificial lighting in caves visited by tourists ("show caves") can stimulate photosynthetic algae and cyanobacteria, called "lampenflora," which are unsightly and damage speleothems and other cave surfaces. The most common mitigation strategy employs bleach, but altering intensities and wavelengths of light might be effective and less harsh. Carlsbad Cavern in New Mexico, a United States National Park and UNESCO World Heritage Site, has visible lampenflora, despite adjustment of LED lamps to decrease the energetic blue light. This study characterized the lampenflora communities and tested effects of color temperature, light intensity, rock or sediment texture, and time on lampenflora development. DNA amplicon sequence data show a variety of algae and cyanobacteria and also heterotrophic bacteria. This study reveals microbial dynamics during colonization of artificially lit surfaces and indicates that, while lowering color temperature may have an effect, management of lampenflora will likely require additional chemical or UV treatment.

RevDate: 2021-01-16

Graf AC, Leonard A, Schäuble M, et al (2019)

Virulence Factors Produced by Staphylococcus aureus Biofilms Have a Moonlighting Function Contributing to Biofilm Integrity.

Molecular & cellular proteomics : MCP, 18(6):1036-1053.

Staphylococcus aureus is the causative agent of various biofilm-associated infections in humans causing major healthcare problems worldwide. This type of infection is inherently difficult to treat because of a reduced metabolic activity of biofilm-embedded cells and the protective nature of a surrounding extracellular matrix (ECM). However, little is known about S. aureus biofilm physiology and the proteinaceous composition of the ECM. Thus, we cultivated S. aureus biofilms in a flow system and comprehensively profiled intracellular and extracellular (ECM and flow-through (FT)) biofilm proteomes, as well as the extracellular metabolome compared with planktonic cultures. Our analyses revealed the expression of many pathogenicity factors within S. aureus biofilms as indicated by a high abundance of capsule biosynthesis proteins along with various secreted virulence factors, including hemolysins, leukotoxins, and lipases as a part of the ECM. The activity of ECM virulence factors was confirmed in a hemolysis assay and a Galleria mellonella pathogenicity model. In addition, we uncovered a so far unacknowledged moonlighting function of secreted virulence factors and ribosomal proteins trapped in the ECM: namely their contribution to biofilm integrity. Mechanistically, it was revealed that this stabilizing effect is mediated by the strong positive charge of alkaline virulence factors and ribosomal proteins in an acidic ECM environment, which is caused by the release of fermentation products like formate, lactate, and acetate because of oxygen limitation in biofilms. The strong positive charge of these proteins most likely mediates electrostatic interactions with anionic cell surface components, eDNA, and anionic metabolites. In consequence, this leads to strong cell aggregation and biofilm stabilization. Collectively, our study identified a new molecular mechanism during S. aureus biofilm formation and thus significantly widens the understanding of biofilm-associated S. aureus infections - an essential prerequisite for the development of novel antimicrobial therapies.

RevDate: 2021-01-16

Chmielewski RAN, JF Frank (2003)

Biofilm Formation and Control in Food Processing Facilities.

Comprehensive reviews in food science and food safety, 2(1):22-32.

Microorganisms on wet surfaces have the ability to aggregate, grow into microcolonies, and produce biofilm. Growth of biofilms in food processing environments leads to increased opportunity for microbial contamination of the processed product. These biofilms may contain spoilage and pathogenic microorganisms. Microorganisms within biofilms are protected from sanitizers increasing the likelihood of survival and subsequent contamination of food. This increases the risk of reduced shelf life and disease transmission. Extracellular polymeric substances associated with biofilm that are not removed by cleaning provide attachment sites for microorganisms newly arrived to the cleaned system. Biofilm formation can also cause the impairment of heat transfer and corrosion to metal surfaces. Some of the methods used to control biofilm formation include mechanical and manual cleaning, chemical cleaning and sanitation, and application of hot water.

RevDate: 2021-01-15

Reichert G, Hilgert S, Alexander J, et al (2021)

Determination of antibiotic resistance genes in a WWTP-impacted river in surface water, sediment, and biofilm: Influence of seasonality and water quality.

The Science of the total environment, 768:144526 pii:S0048-9697(20)38057-8 [Epub ahead of print].

Many pathogenic bacteria are adapted to live in aquatic habitats, which makes rivers possible sources and spread pathways of antibiotic resistance, since they usually receive effluents from wastewater treatment plants (WWTP), possibly containing antibiotic residues and also antibiotic-resistant bacteria. This study investigates different monitoring strategies to identify the occurrence of antibiotic-resistant bacteria in rivers. We analyzed the presence of 13 antibiotic resistance genes (ARGs) and seven gene markers for facultative pathogenic bacteria (FPB) with qPCR in sampling sites upstream and downstream of a small WWTP in Southern Germany. Five sampling campaigns were conducted from February to June 2019. Surface water, sediment, and biofilm samples were analyzed. The biofilm was collected from an artificial sampler placed in the river. blaTEM, ermB, tetM, and sul1 genes were detected in all samples analyzed. The results showed there was a previous background in the river, but the WWTP and the water quality of the river influenced the concentration and occurrence of ARGs and FPB. Genes representing resistance against strong or last-resort antibiotics, such as mecA, blaCMY-2, blaKPC-3, and mcr-1, and multidrug resistance were also detected, mainly in samples collected downstream of the WWTP. Downstream of the WWTP, the occurrence of ARG and FPB correlated with ammoniacal nitrogen, while upstream of the WWTP correlated with turbidity, suspended solids, and seasonal factors such as UVA radiation and the presence of macrophytes. Biofilm samples presented higher abundances of ARGs and FPB. The biofilm sampler was efficient and allowed to collect biofilms from specific periods, which helped to identify seasonal patterns.

RevDate: 2021-01-15

Irmscher T, Roske Y, Gayk I, et al (2021)

Pantoea stewartii WceF is a glycan biofilm modifying enzyme with a bacteriophage tailspike-like fold.

The Journal of biological chemistry pii:S0021-9258(21)00055-7 [Epub ahead of print].

Pathogenic microorganisms often reside in glycan-based biofilms. Concentration and chain length distribution of these mostly anionic exopolysaccharides (EPS) determine the overall biophysical properties of a biofilm and result in a highly viscous environment. Bacterial communities regulate this biofilm state via intracellular small-molecule signaling to initiate EPS synthesis. Reorganization or degradation of this glycan matrix, however, requires the action of extracellular glycosidases. So far, these were mainly described for bacteriophages that must degrade biofilms for gaining access to host bacteria. The plant pathogen Pantoea stewartii (P. stewartii) encodes the protein WceF within its EPS synthesis cluster. WceF has homologs in various biofilm forming plant pathogens of the Erwinia family. In this work we show that WceF is a glycosidase active on stewartan, the main P. stewartii EPS biofilm component. WceF has remarkable structural similarity with bacteriophage tailspike proteins (TSPs). Crystal structure analysis showed a native trimer of right-handed parallel β-helices. Despite of its similar fold, WceF lacks the high stability found in bacteriophage TSPs. WceF is a stewartan hydrolase and produces oligosaccharides, corresponding to single stewartan repeat units. However, compared to a stewartan-specific glycan hydrolase of bacteriophage origin, WceF showed lectin-like autoagglutination with stewartan, resulting in notably slower EPS cleavage velocities. This emphasizes that the bacterial enzyme WceF has a role in P. stewartii biofilm glycan matrix reorganization clearly different from that of a bacteriophage exopolysaccharide depolymerase.

RevDate: 2021-01-15

Wang H, Song Z, Gu J, et al (2019)

Nitrogen-Doped Carbon Quantum Dots for Preventing Biofilm Formation and Eradicating Drug-Resistant Bacteria Infection.

ACS biomaterials science & engineering, 5(9):4739-4749.

The development of novel antimicrobial agents is a top priority in the fight against drug-resistant bacteria. Here, we synthesized a green nanoantibiotic, nitrogen-doped carbon quantum dots (N-CQDs) from bis-quaternary ammonium salt (BQAS) as carbon and nitrogen sources. The as-obtained N-CQDs possess high antibacterial activity (>99%) against both methicillin-resistant Staphylococcus aureus (MRSA) and Ampicillin-resistant Escherichia coli bacteria in vitro than some known clinical antibiotics (vancomycin and gentamicin). The N-CQDs can kill MRSA pathogens without inducing resistance, prevent biofilm formation and eliminate established biofilm and persister cells. The treatment of N-CQDs can significantly reduce the amount of bacteria on the infected tissue and accelerate wound healing. The N-CQDs are positively charged, thus enabling them to interact with bacterial cell membrane through electrostatic interaction, leading to severe damage and an increased permeability of the cell membrane, which further promotes the penetration of N-CQDs into the membrane and induces the degradation of DNA by N-CQDs generated reactive oxygen species. The N-CQDs also play a role in obstructing the intracellular metabolic pathways of MRSA. The overall data demonstrate the green nanoantibiotic as an excellent eradicator of biofilm and persister cells as well as a promising antibacterial candidate for treating infections induced by drug-resistant bacteria.

RevDate: 2021-01-15

Steinchen W, Ahmad S, Valentini M, et al (2021)

Dual role of a (p)ppGpp- and (p)ppApp-degrading enzyme in biofilm formation and interbacterial antagonism.

Molecular microbiology [Epub ahead of print].

The guanosine nucleotide-based second messengers ppGpp and pppGpp (collectively: (p)ppGpp) enable adaptation of microorganisms to environmental changes and stress conditions. In contrast, the closely related adenosine nucleotides (p)ppApp are involved in type VI secretion system (T6SS)-mediated killing during bacterial competition. Long RelA-SpoT Homolog (RSH) enzymes regulate synthesis and degradation of (p)ppGpp (and potentially also (p)ppApp) through their synthetase and hydrolase domains, respectively. Small alarmone hydrolases (SAH) that consist of only a hydrolase domain are found in a variety of bacterial species, including the opportunistic human pathogen Pseudomonas aeruginosa. Here, we present the structure and mechanism of P. aeruginosa SAH showing that the enzyme promiscuously hydrolyses (p)ppGpp and (p)ppApp in a strictly manganese-dependent manner. While being dispensable for P. aeruginosa growth or swimming, swarming and twitching motilities, its enzymatic activity is required for biofilm formation. Moreover, (p)ppApp-degradation by SAH provides protection against the T6SS (p)ppApp synthetase effector Tas1, suggesting that SAH enzymes can also serve as defense proteins during interbacterial competition.

RevDate: 2021-01-15

Fleming D, Redman W, Welch GS, et al (2020)

Utilizing glycoside hydrolases to improve the quantitation and visualization of biofilm bacteria.

Biofilm, 2:100037 pii:S2590-2075(20)30020-4.

The complexity of microbial biofilms offers several challenges to the use of traditional means of microbial research. In particular, it can be difficult to calculate accurate numbers of biofilm bacteria, because even after thorough homogenization or sonication, small pieces of the biofilm remain, which contain numerous bacterial cells and result in inaccurately low colony forming units (CFU). In addition, imaging of infected tissue ex vivo often results in a disparity between the CFU and the number of bacterial cells observed under the microscope. We hypothesized that this phenomenon is due to the biofilm extracellular polymeric substance decreasing the accessibility of stains and antibodies to the embedded bacterial cells. In this study, we describe incorporating EPS-degrading glycoside hydrolases for CFU determination to obtain a more accurate estimation of the viable cells and for immunohistochemistry to disrupt the biofilm matrix and increase primary antibody binding to the bacterial cells.

RevDate: 2021-01-15

da Silva GOA, Pennafirme S, da Costa Pereira D, et al (2020)

Monitoring of bacterial community structure and growth: An alternative tool for biofilm microanalysis.

Biofilm, 2:100034 pii:S2590-2075(20)30016-2.

Microorganisms, such as bacteria, tend to aggregate and grow on surfaces, secreting extracellular polymeric substances (EPS), forming biofilms. Biofilm formation is a life strategy, because through it microorganisms can create their own microhabitats. Whether for remediation of pollutants or application in the biomedical field, several methodological approaches are necessary for a more accurate analysis of the role and potential use of bacterial biofilms. The use of computerized microtomography to monitor biofilm growth appears to be an advantageous tool due to its non-destructive character and its ability to render 2D and 3D visualization of the samples. In this study, we used several techniques such as analysis of microbiological parameters and biopolymer concentrations to corroborate porosity quantified by 2D and 3D imaging. Quantification of the porosity of samples by microtomography was verified by increased enzymatic activity and, consequently, higher EPS biopolymer synthesis to form biofilm, indicating growth of the biofilm over 96 ​h. Our interdisciplinary approach provides a better understanding of biofilm growth, enabling integrated use of these techniques as an important tool in bioremediation studies of environments impacted by pollutants.

RevDate: 2021-01-15

Maale GE, Eager JJ, Srinivasaraghavan A, et al (2020)

The evolution from the two stage to the one stage procedure for biofilm based periprosthetic joint infections (PJI).

Biofilm, 2:100033 pii:S2590-2075(20)30015-0.

A definitive consensus on the optimal limb salvage protocol for infected total joints does not currently exist. Popular, is the two-stage revision which calls for the use of an antibiotic loaded spacer followed by a delayed exchange. Our question is whether single-stage revisions for biofilm based infected arthroplasties results in comparable or possibly better patient outcomes as compared to those reported for two-stage revisions. We retrospectively reviewed 500 cases of one-stage revisions for periprosthetic joint infections (PJI) using dual setup with radical debridement, definitive reconstruction with antibiotic loaded cement and implantation of antibiotic calcium sulfate pellets between the years 2005-2017. The revisions included 351 total knees, 122 hips, 2 hip-femur-knees, 13 shoulders, 10 elbows, and 2 shoulder-humerus-elbows. The patient population had a mean follow-up of 60 months (range: 24 months-14 years) and mean patient age of 61 years old, consisting of 250 males and 250 females. Patient comorbidities were reviewed, classified using McPherson's staging for PJIs, and compared to the Cierny & Mader classification system. Successful treatment was defined as a joint without recurrence of infection, for a minimum of 2 years, and limb preservation. Based on our findings, one-stage revision of PJIs demonstrates at least as good an infection eradication rate as two-stage revision: 88% vs 85% respectively.

RevDate: 2021-01-15

Williams DL, Kawaguchi B, Taylor NB, et al (2020)

In vivo efficacy of a unique first-in-class antibiofilm antibiotic for biofilm-related wound infections caused by Acinetobacter baumannii.

Biofilm, 2:100032 pii:S2590-2075(20)30014-9.

Wounds complicated by biofilms challenge even the best clinical care and can delay a return to duty for service members. A major component of treatment in wounded warriors includes infected wound management. Yet, all antibiotic therapy options have been optimized against planktonic bacteria, leaving an important gap in biofilm-related wound care. We tested the efficacy of a unique compound (CZ-01179) specifically synthesized to eradicate biofilms. CZ-01179 was formulated as the active agent in a hydrogel, and tested in vitro and in vivo in a pig excision wound model for its ability to treat and prevent biofilm-related wound infection caused by Acinetobacter baumannii. Data indicated that compared to a clinical standard-silver sulfadiazine-CZ-01179 was much more effective at eradicating biofilms of A. baumannii in vitro and up to 6 days faster at eradicating biofilms in vivo. CZ-01179 belongs to a broader class of newly-synthesized antibiofilm agents (referred to as CZ compounds) with reduced risk of resistance development, specific efficacy against biofilms, and promising formulation potential for clinical applications. Given its broad spectrum and biofilm-specific nature, CZ-01179 gel may be a promising agent to increase the pipeline of products to treat and prevent biofilm-related wound infections.

RevDate: 2021-01-15

Vandeplassche E, Sass A, Ostyn L, et al (2020)

Antibiotic susceptibility of cystic fibrosis lung microbiome members in a multispecies biofilm.

Biofilm, 2:100031 pii:S2590-2075(20)30013-7.

The lungs of cystic fibrosis (CF) patients are often chronically colonized by multiple microbial species that can form biofilms, including the major CF pathogen Pseudomonas aeruginosa. Herewith, lower microbial diversity in CF airways is typically associated with worse health outcomes. In an attempt to treat CF lung infections patients are frequently exposed to antibiotics, which may affect microbial diversity. This study aimed at understanding if common antibiotics that target P. aeruginosa influence microbial diversity. To this end, a microaerophilic multispecies biofilm model of frequently co-isolated members of the CF lung microbiome (Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus anginosus, Achromobacter xylosoxidans, Rothia mucilaginosa, and Gemella haemolysans) was exposed to antipseudomonal antibiotics. We found that antibiotics that affected several dominant species (i.e. ceftazidime, tobramycin) resulted in higher species evenness compared to colistin, which is only active against P. aeruginosa. Furthermore, susceptibility of individual species in the multispecies biofilm following antibiotic treatment was compared to that of the respective single-species biofilms, showing no differences. Adding three anaerobic species (Prevotella melaninogenica, Veillonella parvula, and Fusobacterium nucleatum) to the multispecies biofilm did not influence antibiotic susceptibility. In conclusion, our study demonstrates antibiotic-dependent effects on microbial community diversity of multispecies biofilms comprised of CF microbiome members.

RevDate: 2021-01-15

Sjöberg S, Stairs C, Allard B, et al (2020)

Bubble biofilm: Bacterial colonization of air-air interface.

Biofilm, 2:100030 pii:S2590-2075(20)30012-5.

Microbial mats or biofilms are known to colonize a wide range of substrates in aquatic environments. These dense benthic communities efficiently recycle nutrients and often exhibit high tolerance to environmental stressors, characteristics that enable them to inhabit harsh ecological niches. In some special cases, floating biofilms form at the air-water interface residing on top of a hydrophobic microlayer. Here, we describe biofilms that reside at the air-air interface by forming gas bubbles (bubble biofilms) in the former Ytterby mine, Sweden. The bubbles are built by micrometer thick membrane-like biofilm that holds enough water to sustain microbial activity. Molecular identification shows that the biofilm communities are dominated by the neuston bacterium Nevskia. Gas bubbles contain mostly air with a slightly elevated concentration of carbon dioxide. Biofilm formation and development was monitored in situ using a time-lapse camera over one year, taking one image every second hour. The bubbles were stable over long periods of time (weeks, even months) and gas build-up occurred in pulses as if the bedrock suddenly exhaled. The result was however not a passive inflation of a dying biofilm becoming more fragile with time (as a result of overstretching of the organic material). To the contrary, microbial growth lead to a more robust, hydrophobic bubble biofilm that kept the bubbles inflated for extended periods (several weeks, and in some cases even months).

RevDate: 2021-01-15

Hiebner DW, Barros C, Quinn L, et al (2020)

Surface functionalization-dependent localization and affinity of SiO2 nanoparticles within the biofilm EPS matrix.

Biofilm, 2:100029 pii:S2590-2075(20)30011-3.

The contribution of the biofilm extracellular polymeric substance (EPS) matrix to reduced antimicrobial susceptibility in biofilms is widely recognised. As such, the direct targeting of the EPS matrix is a promising biofilm control strategy that allows for the disruption of the matrix, thereby allowing a subsequent increase in susceptibility to antimicrobial agents. To this end, surface-functionalized nanoparticles (NPs) have received considerable attention. However, the fundamental understanding of the interactions occurring between engineered NPs and the biofilm EPS matrix has not yet been fully elucidated. An insight into the underlying mechanisms involved when a NP interacts with the EPS matrix will aid in the design of more efficient NPs for biofilm control. Here we demonstrate the use of highly specific fluorescent probes in confocal laser scanning microscopy (CLSM) to illustrate the distribution of EPS macromolecules within the biofilm. Thereafter, a three-dimensional (3D) colocalization analysis was used to assess the affinity of differently functionalized silica NPs (SiNPs) and EPS macromolecules from Pseudomonas fluorescens biofilms. Results show that both the charge and surface functional groups of SiNPs dramatically affected the extent to which SiNPs interacted and localized with EPS macromolecules, including proteins, polysaccharides and DNA. Hypotheses are also presented about the possible physicochemical interactions which may be dominant in EPS matrix-NP interactions. This research not only develops an innovative CLSM-based methodology for elucidating biofilm-nanoparticle interactions but also provides a platform on which to build more efficient NP systems for biofilm control.

RevDate: 2021-01-15

Rumbaugh KP (2020)

How well are we translating biofilm research from bench-side to bedside?.

Biofilm, 2:100028 pii:S2590-2075(20)30010-1.

Biofilms are responsible for more than 80% of all chronic infections and represent an enormous medical challenge. In order to meet this challenge, translation research on anti-biofilm approaches is desperately needed. While biofilm research has grown exponentially over the last three decades and provided important details about the mechanisms involved in initiating, maintaining and disrupting bacterial communities, how much of this basic science knowledge has resulted in new therapeutic approaches? In this perspective article biofilm publications, patents, clinical trials and companies were surveyed to ascertain where we stand in translating biofilm research into new strategies to treat and prevent biofilm-associated infections. Overall, the survey data obtained indicate that anti-biofilm research makes up a very small percentage of the total biofilm literature, and the number of patents and clinical studies for anti-biofilm agents is relatively small. However, the forecast for the future of anti-biofilm therapeutics looks promising. Publications on translational studies are trending up and there are a large number of companies selling products marketed to fight biofilm, indicating that there is a significant commercial interest. Researchers can aid in the translational effort by collaborating with clinicians and industry to design and execute clinically relevant pre-clinical studies, which will result in more agents successfully completing clinical studies and entering the market.

RevDate: 2021-01-15

Wille J, T Coenye (2020)

Biofilm dispersion: The key to biofilm eradication or opening Pandora's box?.

Biofilm, 2:100027 pii:S2590-2075(20)30009-5.

Biofilms are extremely difficult to eradicate due to their decreased antibiotic susceptibility. Inducing biofilm dispersion could be a potential strategy to help combat biofilm-related infections. Mechanisms of biofilm dispersion can basically be divided into two groups, i.e. active and passive dispersion. Active dispersion depends on a decrease in the intracellular c-di-GMP levels, leading to the production of enzymes that degrade the biofilm matrix and promote dispersion. In contrast, passive dispersion relies on triggers that directly release cells from the biofilm. In the present review, several active and passive dispersion strategies are discussed. In addition, the disadvantages and possible consequences of using dispersion as a treatment approach for biofilm-related infections are also reviewed.

RevDate: 2021-01-15

Zea L, McLean RJC, Rook TA, et al (2020)

Potential biofilm control strategies for extended spaceflight missions.

Biofilm, 2:100026 pii:S2590-2075(20)30008-3.

Biofilms, surface-adherent microbial communities, are associated with microbial fouling and corrosion in terrestrial water-distribution systems. Biofilms are also present in human spaceflight, particularly in the Water Recovery System (WRS) on the International Space Station (ISS). The WRS is comprised of the Urine Processor Assembly (UPA) and the Water Processor Assembly (WPA) which together recycles wastewater from human urine and recovered humidity from the ISS atmosphere. These wastewaters and various process streams are continually inoculated with microorganisms primarily arising from the space crew microbiome. Biofilm-related fouling has been encountered and addressed in spacecraft in low Earth orbit, including ISS and the Russian Mir Space Station. However, planned future missions beyond low Earth orbit to the Moon and Mars present additional challenges, as resupplying spare parts or support materials would be impractical and the mission timeline would be in the order of years in the case of a mission to Mars. In addition, future missions are expected to include a period of dormancy in which the WRS would be unused for an extended duration. The concepts developed in this review arose from a workshop including NASA personnel and representatives with biofilm expertise from a wide range of industrial and academic backgrounds. Here, we address current strategies that are employed on Earth for biofilm control, including antifouling coatings and biocides and mechanisms for mitigating biofilm growth and damage. These ideas are presented in the context of their applicability to spaceflight and identify proposed new topics of biofilm control that need to be addressed in order to facilitate future extended, crewed, spaceflight missions.

RevDate: 2021-01-15

Cornell WC, Zhang Y, Bendebury A, et al (2020)

Phenazine oxidation by a distal electrode modulates biofilm morphogenesis.

Biofilm, 2:100025 pii:S2590-2075(20)30007-1.

Microbes living in biofilms, dense assemblages of cells, experience limitation for resources such as oxygen when cellular consumption outpaces diffusion. The pathogenic bacterium Pseudomonas aeruginosa has strategies for coping with hypoxia that support cellular redox balancing in biofilms; these include (1) increasing access to oxygen by forming wrinkles in the biofilm surface and (2) electrochemically reducing endogenous compounds called phenazines, which can shuttle electrons to oxidants available at a distance. Phenazine-mediated extracellular electron transfer (EET) has been shown to support survival for P. aeruginosa cells in anoxic liquid cultures, but the physiological relevance of EET over a distance for P. aeruginosa biofilms has remained unconfirmed. Here, we use a custom-built electrochemistry setup to show that phenazine-mediated electron transfer at a distance inhibits wrinkle formation in P. aeruginosa biofilms. This result demonstrates that phenazine-dependent EET to a distal oxidant affects biofilm morphogenesis.

RevDate: 2021-01-15

Schinner S, Engelhardt F, Preusse M, et al (2020)

Genetic determinants of Pseudomonas aeruginosa fitness during biofilm growth.

Biofilm, 2:100023 pii:S2590-2075(20)30005-8.

Pseudomonas aeruginosa is an environmental bacterium and an opportunistic human pathogen. It is also a well-established model organism to study bacterial adaptation to stressful conditions, such as those encountered during an infection process in the human host. Advancing knowledge on P. aeruginosa adaptation to biofilm growth conditions is bound to reveal novel strategies and targets for the treatment of chronic biofilm-associated infections. Here, we generated transposon insertion libraries in three P. aeruginosa strain backgrounds and determined the relative frequency of each insertion following biofilm growth using transposon sequencing. We demonstrate that in general the SOS response, several tRNA modifying enzymes as well as adaptation to microaerophilic growth conditions play a key role in bacterial survival under biofilm growth conditions. On the other hand, presence of genes involved in motility and PQS signaling were less important during biofilm growth. Several mutants exhibiting transposon insertions in genes detected in our screen were validated for their biofilm growth capabilities and biofilm specific transcriptional responses using independently generated transposon mutants. Our results provide new insights into P. aeruginosa adaptation to biofilm growth conditions. The detection of previously unknown determinants of biofilm survival supports the use of transposon insertion sequencing as a global genomic technology for understanding the establishment of difficult to treat biofilm-associated infections.

RevDate: 2021-01-15

Lories B, Belpaire TER, Yssel A, et al (2020)

Agaric acid reduces Salmonella biofilm formation by inhibiting flagellar motility.

Biofilm, 2:100022 pii:S2590-2075(20)30004-6.

Salmonella biofilms are a common cause of contaminations in the food or feed industry. In a screening for novel compounds to combat biofilm-associated foodborne outbreaks, we identified agaric acid as a Salmonella Typhimurium biofilm inhibitor that does not affect planktonic growth. Importantly, the remaining biofilm cells after preventive treatment with agaric acid were significantly more sensitive to the common disinfectant hydrogen peroxide. Screening of a GFP-promoter fusion library of biofilm related genes revealed that agaric acid downregulates the transcription of genes responsible for flagellar motility. Concurrently, swimming motility was completely abrogated in the presence of agaric acid, indicating that biofilm inhibition occurs via interference with the motility phenotype. Moreover, agaric acid also reduced biofilm formation of Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli. Agaric acid thus shows potential as an anti-virulence compound that inhibits both motility and biofilm formation.

RevDate: 2021-01-15

Thérien M, Kiesewalter HT, Auria E, et al (2020)

Surfactin production is not essential for pellicle and root-associated biofilm development of Bacillus subtilis.

Biofilm, 2:100021 pii:S2590-2075(20)30003-4.

Secondary metabolites have an important impact on the biocontrol potential of soil-derived microbes. In addition, various microbe-produced chemicals have been suggested to impact the development and phenotypic differentiation of bacteria, including biofilms. The non-ribosomal synthesized lipopeptide of Bacillus subtilis, surfactin, has been described to impact the plant promoting capacity of the bacterium. Here, we investigated the impact of surfactin production on biofilm formation of B. subtilis using the laboratory model systems; pellicle formation at the air-medium interface and architecturally complex colony development, in addition to plant root-associated biofilms. We found that the production of surfactin by B. subtilis is not essential for pellicle biofilm formation neither in the well-studied strain, NCIB 3610, nor in the newly isolated environmental strains, but lack of surfactin reduces colony expansion. Further, plant root colonization was comparable both in the presence or absence of surfactin synthesis. Our results suggest that surfactin-related biocontrol and plant promotion in B. subtilis strains are independent of biofilm formation.

RevDate: 2021-01-15

Gloag ES, Fabbri S, Wozniak DJ, et al (2020)

Biofilm mechanics: Implications in infection and survival.

Biofilm, 2:100017 pii:S2590-2075(19)30017-6.

It has long been recognized that biofilms are viscoelastic materials, however the importance of this attribute to the survival and persistence of these microbial communities is yet to be fully realized. Here we review work, which focuses on understanding biofilm mechanics and put this knowledge in the context of biofilm survival, particularly for biofilm-associated infections. We note that biofilm viscoelasticity may be an evolved property of these communities, and that the production of multiple extracellular polymeric slime components may be a way to ensure the development of biofilms with complex viscoelastic properties. We discuss viscoelasticity facilitating biofilm survival in the context of promoting the formation of larger and stronger biofilms when exposed to shear forces, promoting fluid-like behavior of the biofilm and subsequent biofilm expansion by viscous flow, and enabling resistance to both mechanical and chemical methods of clearance. We conclude that biofilm viscoelasticity contributes to the virulence of chronic biofilm infections.

RevDate: 2021-01-15

Subramanian S, Huiszoon RC, Chu S, et al (2020)

Microsystems for biofilm characterization and sensing - A review.

Biofilm, 2:100015 pii:S2590-2075(19)30015-2.

Biofilms are the primary cause of clinical bacterial infections and are impervious to typical amounts of antibiotics, necessitating very high doses for elimination. Therefore, it is imperative to have suitable methods for characterization to develop novel methods of treatment that can complement or replace existing approaches using significantly lower doses of antibiotics. This review presents some of the current developments in microsystems for characterization and sensing of bacterial biofilms. Initially, we review current standards for studying biofilms that are based on invasive and destructive end-point biofilm characterization. Additionally, biofilm formation and growth is extremely sensitive to various growth and environmental parameters that cause large variability in biofilms between repeated experiments, making it very difficult to compare experimental repeats and characterize the temporal characteristics of these organisms. To address these challenges, recent developments in the field have moved toward systems and miniature devices that can aid in the non-invasive characterization of bacterial biofilms. Our review focuses on several types of microsystems for biofilm evaluation including optical, electrochemical, and mechanical systems. This review will show how these devices can lead to better understanding of the physiology and function of these communities of bacteria, which can eventually lead to the development of novel treatments that do not rely on high-dosage antibiotics.

RevDate: 2021-01-15

Matysik A, Ho FK, Ler Tan AQ, et al (2020)

Cellular chaining influences biofilm formation and structure in group A Streptococcus.

Biofilm, 2:100013 pii:S2590-2075(19)30013-9.

Group A Streptococcal (GAS) biofilm formation is an important pathological feature contributing to the antibiotic tolerance and progression of various GAS infections. Although a number of bacterial factors have been described to promote in vitro GAS biofilm formation, the relevance of in vitro biofilms to host-associated biofilms requires further understanding. In this study, we demonstrate how constituents of the host environment, such as lysozyme and NaCl, can modulate GAS bacterial chain length and, in turn, shape GAS biofilm morphology and structure. Disruption of GAS chains with lysozyme results in biofilms that are more stable. Based on confocal microscopy, we attribute the increase in biofilm stability to a dense and compact three-dimensional structure produced by de-chained cells. To show that changes in biofilm stability and structure are due to the shortening of bacterial chains and not specific to the activity of lysozyme, we demonstrate that augmented chaining induced by NaCl or deletion of the autolysin gene mur1.2 produced defects in biofilm formation characterized by a loose biofilm architecture. We conclude that GAS biofilm formation can be directly influenced by host and environmental factors through the modulation of bacterial chain length, potentially contributing to persistence and colonization within the host. Further studies of in vitro biofilm models incorporating physiological constituents such as lysozyme may uncover new insights into the physiology of in vivo GAS biofilms.

RevDate: 2021-01-15

Coenye T, Kjellerup B, Stoodley P, et al (2020)

The future of biofilm research - Report on the '2019 Biofilm Bash'.

Biofilm, 2:100012 pii:S2590-2075(19)30012-7.

In May 2019, 29 scientists with expertise in various subdisciplines of biofilm research got together in Leavenworth (WA, USA) at an event designated as the '2019 Biofilm Bash'. The goal of this informal two-day meeting was first to identify gaps in our knowledge, and then to come up with ways how the biofilm community can fill these gaps. The meeting was organized around six questions that covered the most important items brought forward by the organizers and participants. The outcome of these discussions is summarized in the present paper. We are aware that these views represent a small subset of our field, and that inevitably we will have inadvertently overlooked important developing research areas and ideas. We are nevertheless hopeful that this report will stimulate discussions and help create new ways of how we can advance our field.

RevDate: 2021-01-15

Allkja J, Bjarnsholt T, Coenye T, et al (2020)

Minimum information guideline for spectrophotometric and fluorometric methods to assess biofilm formation in microplates.

Biofilm, 2:100010 pii:S2590-2075(19)30010-3.

The lack of reproducibility of published studies is one of the major issues facing the scientific community, and the field of biofilm microbiology has been no exception. One effective strategy against this multifaceted problem is the use of minimum information guidelines. This strategy provides a guide for authors and reviewers on the necessary information that a manuscript should include for the experiments in a study to be clearly interpreted and independently reproduced. As a result of several discussions between international groups working in the area of biofilms, we present a guideline for the spectrophotometric and fluorometric assessment of biofilm formation in microplates. This guideline has been divided into 5 main sections, each presenting a comprehensive set of recommendations. The intention of the minimum information guideline is to improve the quality of scientific communication that will augment interlaboratory reproducibility in biofilm microplate assays.

RevDate: 2021-01-15

Jensen PØ, Møller SA, Lerche CJ, et al (2019)

Improving antibiotic treatment of bacterial biofilm by hyperbaric oxygen therapy: Not just hot air.

Biofilm, 1:100008 pii:S2590-2075(19)30008-5.

Bacteria and fungi show substantial increased recalcitrance when growing as infectious biofilms. Chronic infections caused by biofilm growing microorganisms is considered a major problem of modern medicine. New strategies are needed to improve antibiotic treatment of biofilms. We have improved antibiotic treatment of bacterial biofilms by reviving the dormant bacteria and thereby make them susceptible to antibiotics by means of reoxygenation. Here we review the rationale for associating lack of oxygen with low susceptibility in infectious biofilm, and how hyperbaric oxygen therapy may result in reoxygenation leading to enhanced bactericidal activity of antibiotics. We address issues of feasibility and potential adverse effects regarding patient safety and development of resistance. Finally, we propose means for supplying reoxygenation to antibiotic treatment of infectious biofilm with the potential to benefit large groups of patients.

RevDate: 2021-01-15

Kjeldgaard B, Listian SA, Ramaswamhi V, et al (2019)

Fungal hyphae colonization by Bacillus subtilis relies on biofilm matrix components.

Biofilm, 1:100007 pii:S2590-2075(19)30007-3.

Bacteria interact with their environment including microbes and higher eukaryotes. The ability of bacteria and fungi to affect each other are defined by various chemical, physical and biological factors. During physical association, bacterial cells can directly attach and settle on the hyphae of various fungal species. Such colonization of mycelia was proposed to be dependent on biofilm formation by the bacteria, but the essentiality of the biofilm matrix was not represented before. Here, we demonstrate that secreted biofilm matrix components of the soil-dwelling bacterium, Bacillus subtilis are essential for the establishment of a dense bacterial population on the hyphae of the filamentous black mold fungus, Aspergillus niger and the basidiomycete mushroom, Agaricus bisporus. We further illustrate that these matrix components can be shared among various mutants highlighting the community shaping impact of biofilm formers on bacteria-fungi interactions.

RevDate: 2021-01-15

Kragh KN, Alhede M, Kvich L, et al (2019)

Into the well-A close look at the complex structures of a microtiter biofilm and the crystal violet assay.

Biofilm, 1:100006 pii:S2590-2075(19)30006-1.

The microtiter assay is one of the most widely used methods for assessing biofilm formation. Though it has high throughput, this assay is known for its substantial deviation from experiment to experiment, and even from well to well. Since the assay constitutes one of the pillars of biofilm research, it was decided to examine the wells of a microtiter plate directly during growth, treatment, and the steps involved in crystal violet (CV) measurements. An inverted Zeiss LSM 880 confocal laser scanning microscope was used to visualize and quantify biomass directly in the wells of the microtiter plate. Green fluorescent protein-tagged Pseudomonas aeruginosa, PAO1, and live/dead stains were used to assess the structure, state, and position of biomass build-up. Microscopic observations were compared with colony-forming unit (CFU) and CV measurements. The development and the structured architecture of biomass was observed in real-time in the wells. Three-dimensional images of biomass were obtained from all of the microtiter wells; these showed variations from well to well. CV staining showed large variations in remaining biomass, depending on the method selected to remove the supernatant prior to CV staining (i.e. pipetting or manually discarding the fluid by inversion, washed or unwashed wells). Colony-forming unit counts or live/dead staining used to evaluate biomass with or without antibiotic treatment proved imprecise due to aggregation, limited removal of biomass, and overestimation of dead staining. The highly structured microenvironment of biomass in microtiter wells needs to be considered when designing and analyzing experiments. When using microtiter plates, stochastic variation due to growth and handling may lead to flawed conclusions. It is therefore recommended that this assay be used as a screening tool rather than as a stand-alone experimental tool.

RevDate: 2021-01-15

Ha PT, He R, Killiny N, et al (2019)

Host-free biofilm culture of "Candidatus Liberibacter asiaticus," the bacterium associated with Huanglongbing.

Biofilm, 1:100005 pii:S2590-2075(19)30005-X.

Inability to culture the phloem-restricted alpha-proteobacterium "Candidatus Liberibacter asiaticus" ("Ca. L. asiaticus") or the closely related species ("Candidatus Liberibacter americanus" and "Candidatus Liberibacter africanus") that are associated with Huanglongbing (HLB) hampers the development of effective long-term control strategies for this devastating disease. Here we report successful establishment and long-term maintenance of host-free "Ca. L. asiaticus" cultures, with the bacterium growing within cultured biofilms derived from infected citrus tissue. The biofilms were grown in a newly designed growth medium under specific conditions. The initial biofilm-based culture has been successfully maintained for over two years and has undergone over a dozen subcultures. Multiple independent cultures have been established and maintained in a biofilm reactor system, opening the door to the development of pure culture of "Ca. L. asiaticus" and the use of genetics-based methods to understand and mitigate the spread of HLB.

RevDate: 2021-01-15

Coenye T, Kjellerup BV, Kovács ÁT, et al (2019)

Biofilm: Introducing a new journal for the broad biofilm field.

Biofilm, 1:100003 pii:S2590-2075(19)30003-6.

RevDate: 2021-01-15

Van Acker H, Crabbé A, Jurėnas D, et al (2019)

The role of small proteins in Burkholderia cenocepacia J2315 biofilm formation, persistence and intracellular growth.

Biofilm, 1:100001 pii:S2590-2075(19)30001-2.

Burkholderia cenocepacia infections are difficult to treat due to resistance, biofilm formation and persistence. B. cenocepacia strain J2315 has a large multi-replicon genome (8.06 Mb) and the function of a large fraction of (conserved) hypothetical genes remains elusive. The goal of the present study is to elucidate the role of small proteins in B. cenocepacia, focusing on genes smaller than 300 base pairs of which the function is unknown. Almost 10% (572) of the B. cenocepacia J2315 genes are smaller than 300 base pairs and more than half of these are annotated as coding for hypothetical proteins. For 234 of them no similarity could be found with non-hypothetical genes in other bacteria using BLAST. Using available RNA sequencing data obtained from biofilms, a list of 27 highly expressed B. cenocepacia J2315 genes coding for small proteins was compiled. For nine of them expression in biofilms was also confirmed using LC-MS based proteomics and/or expression was confirmed using eGFP translational fusions. Overexpression of two of these genes negatively impacted growth, whereas for four others overexpression led to an increase in biofilm biomass. Overexpression did not have an influence on the MIC for tobramycin, ciprofloxacin or meropenem but for five small protein encoding genes, overexpression had an effect on the number of persister cells in biofilms. While there were no significant differences in adherence to and invasion of A549 epithelial cells between the overexpression mutants and the WT, significant differences were observed in intracellular growth/survival. Finally, the small protein BCAM0271 was identified as an antitoxin belonging to a toxin-antitoxin module. The toxin was found to encode a tRNA acetylase that inhibits translation. In conclusion, our results confirm that small proteins are present in the genome of B. cenocepacia J2315 and indicate that they are involved in various biological processes, including biofilm formation, persistence and intracellular growth.

RevDate: 2021-01-15

Arif S, Nacke H, M Hoppert (2021)

Metagenome-Assembled Genome Sequences of a Biofilm Derived from Marsberg Copper Mine.

Microbiology resource announcements, 10(2):.

We sequenced the metagenome of a biofilm collected near a leachate stream of the Marsberg copper mine (Germany) and reconstructed eight metagenome-assembled genomes. These genomes yield copper resistance through Cu(I) oxidation via multiple copper oxidases and extrusion through copper-exporting P-type ATPases.

RevDate: 2021-01-15

Relucenti M, Familiari G, Donfrancesco O, et al (2021)

Microscopy Methods for Biofilm Imaging: Focus on SEM and VP-SEM Pros and Cons.

Biology, 10(1): pii:biology10010051.

Several imaging methodologies have been used in biofilm studies, contributing to deepening the knowledge on their structure. This review illustrates the most widely used microscopy techniques in biofilm investigations, focusing on traditional and innovative scanning electron microscopy techniques such as scanning electron microscopy (SEM), variable pressure SEM (VP-SEM), environmental SEM (ESEM), and the more recent ambiental SEM (ASEM), ending with the cutting edge Cryo-SEM and focused ion beam SEM (FIB SEM), highlighting the pros and cons of several methods with particular emphasis on conventional SEM and VP-SEM. As each technique has its own advantages and disadvantages, the choice of the most appropriate method must be done carefully, based on the specific aim of the study. The evaluation of the drug effects on biofilm requires imaging methods that show the most detailed ultrastructural features of the biofilm. In this kind of research, the use of scanning electron microscopy with customized protocols such as osmium tetroxide (OsO4), ruthenium red (RR), tannic acid (TA) staining, and ionic liquid (IL) treatment is unrivalled for its image quality, magnification, resolution, minimal sample loss, and actual sample structure preservation. The combined use of innovative SEM protocols and 3-D image analysis software will allow for quantitative data from SEM images to be extracted; in this way, data from images of samples that have undergone different antibiofilm treatments can be compared.

RevDate: 2021-01-15

Camargo SEA, Roy T, Xia X, et al (2021)

Novel Coatings to Minimize Corrosion of Titanium in Oral Biofilm.

Materials (Basel, Switzerland), 14(2): pii:ma14020342.

The aim of this work is to investigate the effects produced by polymicrobial biofilm (Porphyromonas gingivalis, Streptococcus mutans, Streptococcus sanguinis, and Streptococcus salivarius) on the corrosion behavior of titanium dental implants. Pure titanium disks were polished and coated with titanium nitride (TiN) and silicon carbide (SiC) along with their quarternized versions. Next, the disks were cultivated in culture medium (BHI) with P. gingivalis, S. mutans, S. sanguinis, and S. salivarius and incubated anaerobically at 37 °C for 30 days. Titanium corrosion was evaluated through surface observation using Scanning Electron Microscope (SEM) and Atomic Force Microscopy (AFM). Furthermore, the Ti release in the medium was evaluated by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). SEM images showed that coated Ti disks exhibited lower corrosion compared to non-coated disks, except for the quartenized TiN. This was confirmed by AFM, where the roughness was higher in non-coated Ti disks. ICP showed that Ti levels were low in all coating disks. These results indicate that these SiC and TiN-based coatings could be a useful tool to reduce surface corrosion on titanium implant surfaces.

RevDate: 2021-01-14

El Far A, Samir S, El-Gebaly E, et al (2021)

Assessment of eugenol inhibitory effect on biofilm formation and biofilm gene expression in methicillin resistant Staphylococcus aureus clinical isolates in Egypt.

Infection, genetics and evolution : journal of molecular epidemiology and evolutionary genetics in infectious diseases pii:S1567-1348(21)00019-8 [Epub ahead of print].

Methicillin-resistant Staphylococcus aureus (MRSA) biofilm infection is a major threat in Healthcare facilities. The search for biofilm inhibitors is essential to overcome the antibiotic resistance. Eugenol is a phyto-compound that possesses many biological properties. In this study, the aim was to estimate the effect of eugenol on biofilms of MRSA through quantifying the level of gene expression of three genes (IcaA, IcaD and SarA) involved in biofilm development.. Fifty MRSA biofilm producers collected from the microbiology lab at Theodor Bilharz Research Institute were incubated with different concentrations of eugenol for 24 h. The minimum inhibitory concentration of eugenol (MIC) that eradicates the biofilms growth was detected. mRNA was extracted from all isolates before and after the application of eugenol at 0.5 x MIC, and then subjected to quantitative real-time PCR (qPCR). Results showed that fourteen isolates out of 50 (28%) exhibited intermediate biofilm formation ability, and 36 out of 50 (72%) were strong biofilm producers. The MIC values of eugenol for MRSA ranged from 3.125% to 0.01%. The mean values of MIC in both strong and intermediate biofilm forming MRSA isolates were statistically comparable (p = 0.202). qPCR results revealed that the levels of expression of the studied genes IcaA, IcaD, and SarA were decreased after eugenol treatment when compared with their corresponding values before treatment (p = 0.001). Eugenol inhibited the formation of biofilm of MRSA isolates, indicating it could be used to control infections associated with MRSA biofilms.

RevDate: 2021-01-14

Kannan S, Solomon A, Krishnamoorthy G, et al (2021)

Liposome encapsulated surfactant abetted copper nanoparticles alleviates biofilm mediated virulence in pathogenic Pseudomonas aeruginosa and MRSA.

Scientific reports, 11(1):1102.

In the present study lipopeptide biosurfactant with high emulsification capacity produced by human skin bacterium Paenibacillus thiaminolyticus was purified and subjected to FTIR and NMR spectral analysis which gave evidence of the active characteristics of the surfactant. To augment the antivirulent potential further, the mixer of copper and copper oxide nanoparticles (CuNPs) was synthesized, and characterized by UV-Visible spectroscopy, SEM-EDAX, TEM, and Zeta analysis. Here, we attempted to enhance the antimicrobial and antibiofilm activity with the assistance of encapsulated preparation of lipopeptide and CuNPs in multilamellar liposomes. The proposed mechanism of action of lipopeptide and CuNPs liposomal preparation negatively influences the cell metabolism, secreted virulence such as staphyloxanthin, pyocyanin, and extracellular polysaccharides. The significant decline in the growth of MRSA and P. aeruginosa in both planktonic form and biofilm by lipopeptide and CuNPs treatment were visualized using scanning electron microscopy and High content screening imaging system. In vivo studies revealed that treatment with lipopeptide and CuNPs in multilamellar liposomes extended the lifespan of infected Caenorhabditis elegans by about 75%. Therefore, this study typifies lipopeptide and CuNPs could credibly be a substantial substitute over conventional antibiotics in averting the biofilm associated pathogenesis of MRSA and P. aeruginosa.

RevDate: 2021-01-14

Caro-Astorga J, Frenzel E, Perkins JR, et al (2020)

Biofilm formation displays intrinsic offensive and defensive features of Bacillus cereus.

NPJ biofilms and microbiomes, 6(1):3.

Biofilm formation is a strategy of many bacterial species to adapt to a variety of stresses and has become a part of infections, contaminations, or beneficial interactions. In this study, we demonstrate that profound physiological changes permit Bacillus cereus to switch from a floating to a sessile lifestyle, to undergo further maturation of the biofilm and to differentiate into the offensive or defensive features. We report that floating and biofilm cells are populations that differentiate metabolically, with members of each subpopulation developing different branches of certain metabolic pathways. Secondly, biofilm populations rearrange nucleotides, sugars, amino acids, and energy metabolism. Thirdly, this metabolic rearrangement coexists with: the synthesis of the extracellular matrix, sporulation, reinforcement of the cell wall, activation of the ROS detoxification machinery and production of secondary metabolites. This strategy contributes to defend biofilm cells from competitors. However, floating cells maintain a fermentative metabolic status that ensures a higher aggressiveness against hosts, evidenced by the production of toxins. The maintenance of the two distinct subpopulations is an effective strategy to face different environmental conditions found in the life styles of B. cereus.

RevDate: 2021-01-13

Han X, Zhang G, Chai M, et al (2021)

Light-assisted therapy for biofilm infected micro-arc oxidation TiO2coating on bone implants.

Biomedical materials (Bristol, England) [Epub ahead of print].

Implant-associated infections is a main factor leading to the failure of titanium (Ti) implants. Micro-arc oxidation is a convenient and effective technique to form a biocompatible metal (Ag+, Cu2+ and Zn2+) ions-doped TiO2 coatings to combat bacterial infections. However, compared with the sterilization by metal ions, light-triggered antibacterial therapies have accepted more attention due to its higher antibacterial efficiency and security. Although TiO2 is an excellent photocatalyst, it can be triggered by ultraviolet light due to the wide band gap. Herein, molybdenum disulfide (MoS2) modified TiO2 coating was fabricated on Ti by a hybrid process of micro-arc oxidation and hydrothermal treatment. The hybrid coating exhibits excellent antibacterial activity under the irradiation of 808 nm near-infrared (NIR) light because of the synergistic antibacterial effects of reactive oxygen species (ROS) and hyperthermia, and Staphylococcus aureus (S. aureus) biofilm can be eradicated within 15 minutes both in vivo and in vitro. Furthermore, collagen decorated on the surface of the hybrid coating can improve the proliferation, adhesion and spreading of MC3T3-E1 osteoblasts.

RevDate: 2021-01-13

Bellich B, Jou IA, Buriola C, et al (2020)

The biofilm of Burkholderia cenocepacia H111 contains an exopolysaccharide composed of l-rhamnose and l-mannose: Structural characterization and molecular modelling.

Carbohydrate research, 499:108231 pii:S0008-6215(20)30602-9 [Epub ahead of print].

Burkholderia cenocepacia belongs to the Burkholderia Cepacia Complex, a group of 22 closely related species both of clinical and environmental origin, infecting cystic fibrosis patients. B. cenocepacia accounts for the majority of the clinical isolates, comprising the most virulent and transmissible strains. The capacity to form biofilms is among the many virulence determinants of B. cenocepacia, a characteristic that confers enhanced tolerance to some antibiotics, desiccation, oxidizing agents, and host defenses. Exopolysaccharides are a major component of biofilm matrices, particularly providing mechanical stability to biofilms. Recently, a water-insoluble exopolysaccharide produced by B. cenocepacia H111 in biofilm was characterized. In the present study, a water-soluble exopolysaccharide was extracted from B. cenocepacia H111 biofilm, and its structure was determined by GLC-MS, NMR and ESI-MS. The repeating unit is a linear rhamno-tetrasaccharide with 50% replacement of a 3-α-L-Rha with a α-3-L-Man. [2)-α-L-Rhap-(1→3)-α-L-[Rhap or Manp]-(1→3)-α-L-Rhap-(1→2)-α-L-Rhap-(1→]n Molecular modelling was used to obtain information about local structural motifs which could give information about the polysaccharide conformation.

RevDate: 2021-01-13

Gupta P, Goel A, Singh KR, et al (2021)

Dissecting the anti-biofilm potency of kappa-carrageenan capped silver nanoparticles against Candida species.

International journal of biological macromolecules pii:S0141-8130(21)00056-8 [Epub ahead of print].

Global antimicrobial crisis and advent of drug resistant fungal strains has substantially distressed disease management for clinicians. Biodegradable silver nanoparticles (AgNps) emerge as an excellent alternative remedial option. In the current study, the anti-biofilm activity of microwave irradiated kappa-carrageenan (CRG) capped AgNps against Candida albicans, and Candida glabrata was investigated in terms of their effect on reactive oxygen species (ROS) generation, cellular morphology, biochemical composition, and the activity of enzymes of extracellular matrix. Minimum inhibitory concentration and fungicidal concentration value of CRG-AgNps against both Candida spp. ranged between 400 and 500 μg/ml. The 80% of Candida biofilm was inhibited and eradicated by CRG-AgNps at a concentration of ~300 μg/ml. Microscopic studies indicate that CRG-AgNps caused morphological damage through membrane disruption and pore formation. Further, CRG-AgNps generated ROS in a concentration-dependent manner and modulated the composition of Candida biofilm ECM by increasing the carbohydrate and eDNA content. CRG-AgNps also significantly inactivated the hydrolytic enzymes, thus hindering the biofilm forming ability. In conclusion, all these results suggest that the CRG-AgNps are potential antifungal agents against Candida biofilms, and they inhibit/eradicate the fungal biofilms through multiple signalling mechanisms.

RevDate: 2021-01-13

Serena TE, Jalodi O, Serena L, et al (2021)

Evaluation of the combination of a biofilm-disrupting agent and negative pressure wound therapy: a case series.

Journal of wound care, 30(1):9-14.

OBJECTIVE: Approximately three million people in the US have hard-to-heal pressure ulcers (PUs), including 10% of hospitalised patients. Healing depends on ulcer stage and patient comorbidities. Despite advances in nutrition and wound care, PUs can take months or years to reach complete closure. To date, clinical studies have focused on single modality therapy. However, there is no one therapy that can address all of the deficits in these complex, hard-to-heal wounds. A commonly used treatment for PUs, negative pressure wound therapy (NPWT), has demonstrated improved healing in Stage 3 and 4 PUs. NPWT entails applying suction to a porous sponge fitted into the wound cavity and sealed with an occlusive dressing. Negative pressure facilitates wound healing by removing wound fluid containing harmful proteases, stimulating the formation of granulation tissue and promoting wound contracture. However, it does not affect biofilm formation. We hypothesised that adding an antibiofilm agent might increase the effectiveness of NPWT in recalcitrant PUs.

METHOD: A prospective case series was conducted in outpatient wound care centres and a skilled nursing facility to examine the combination of a biofilm-disrupting antimicrobial agent (Blast-X, Next Science, US) in combination with NPWT (VAC, 3M, US) in healing and reducing bacterial burden in treatment-resistant pressure ulcers. Patients consented to application of the antibiofilm agent and NPWT three times per week for four weeks. The wounds were measured, imaged for bacteria and tested for host and bacterial protease activity weekly.

RESULTS: Of the 10 patients, four dropped out of the study before the end of the four weeks. Of the remaining six, four patients experienced a reduction in wound surface area and volume, reduced protease activity and lower bacterial levels.

CONCLUSION: The results of this study showed that multimodal therapy, including NPWT and biofilm disruption, may restart the healing of stagnant treatment-resistant PUs.

RevDate: 2021-01-13

Wei Q, Zhang Z, Luo J, et al (2020)

Erratum: Insulin treatment enhances pseudomonas aeruginosa biofilm formation by increasing intracellular cyclic di-GMP levels, leading to chronic wound infection and delayed wound healing.

American journal of translational research, 12(12):8259-8261.

[This corrects the article on p. 3261 in vol. 11, PMID: 31312343.].

RevDate: 2021-01-13

Landlinger C, Tisakova L, Oberbauer V, et al (2021)

Engineered Phage Endolysin Eliminates Gardnerella Biofilm without Damaging Beneficial Bacteria in Bacterial Vaginosis Ex Vivo.

Pathogens (Basel, Switzerland), 10(1): pii:pathogens10010054.

Bacterial vaginosis is characterized by an imbalance of the vaginal microbiome and a characteristic biofilm formed on the vaginal epithelium, which is initiated and dominated by Gardnerella bacteria, and is frequently refractory to antibiotic treatment. We investigated endolysins of the type 1,4-beta-N-acetylmuramidase encoded on Gardnerella prophages as an alternative treatment. When recombinantly expressed, these proteins demonstrated strong bactericidal activity against four different Gardnerella species. By domain shuffling, we generated several engineered endolysins with 10-fold higher bactericidal activity than any wild-type enzyme. When tested against a panel of 20 Gardnerella strains, the most active endolysin, called PM-477, showed minimum inhibitory concentrations of 0.13-8 µg/mL. PM-477 had no effect on beneficial lactobacilli or other species of vaginal bacteria. Furthermore, the efficacy of PM-477 was tested by fluorescence in situ hybridization on vaginal samples of fifteen patients with either first time or recurring bacterial vaginosis. In thirteen cases, PM-477 killed the Gardnerella bacteria and physically dissolved the biofilms without affecting the remaining vaginal microbiome. The high selectivity and effectiveness in eliminating Gardnerella, both in cultures of isolated strains as well as in clinically derived samples of natural polymicrobial biofilms, makes PM-477 a promising alternative to antibiotics for the treatment of bacterial vaginosis, especially in patients with frequent recurrence.

RevDate: 2021-01-13

Mushtaq S, Ahmad NM, Mahmood A, et al (2021)

Antibacterial Amphiphilic Copolymers of Dimethylamino Ethyl Methacrylate and Methyl Methacrylate to Control Biofilm Adhesion for Antifouling Applications.

Polymers, 13(2): pii:polym13020216.

Amphiphilic copolymers are recognized as important biomaterials and used as antibacterial agents due to their effective inhibition of bacterial growth. In current study, the amphiphilic copolymers of P(DMAEMA-co-MMA) were synthesized using free radical polymerization by varying the concentrations of hydrophilic monomer 2-dimethylamino ethylmethacrylate (DMAEMA) and hydrophobic monomer methyl methacrylate (MMA) having PDI value of 1.65-1.93. The DMAEMA monomer, through ternary amine with antibacterial property optimized copolymers, P(DMAEMA-co-MMA), compositions to control biofilm adhesion. Antibacterial activity of synthesized copolymers was elucidated against Gram-positive Staphylococcus aureus (ATCC 6538) and Gram-negative Escherchia coli (ATCC 8739) by disk diffusion method, and zones of inhibition were measured. The desired composition that was PDM1 copolymer had shown good zones of inhibition i.e., 19 ± 0.33 mm and 20 ± 0.33 mm for E. coli and S. aureus respectively. The PDM1 and PDM2 have exhibited significant control over bacterial biofilm adhesion as tested by six well plate method. SEM study of bacterial biofilm formation has illustrated that these copolymers act in a similar fashion like cationic biocide. These compositions viz. PDM1 and PDM2, may be useful in development of bioreactors, sensors, surgical equipment and drug delivery devices.

RevDate: 2021-01-13

Slettengren M, Linnros M, J van der Linden (2021)

Silicone Oil Decreases Biofilm Formation in a Capacitance-Based Automatic Urine Measurement System.

Sensors (Basel, Switzerland), 21(2): pii:s21020445.

Capacitance-based automatic urine measurement is a validated technique already implemented in clinical practice. However, albuminuria and free hemoglobinuria cause progressive biofilm buildup on the capacitance sensors of the urinometers. The aim of this experimental study is to investigate the influence of albumin and free hemoglobin on the capacitance signal of an automatic urinometer with and without the addition of silicone oil. A solution of Ringer's acetate mixed with either albumin or free hemoglobin was run through an automatic urinometer containing either a water-soluble capsule with silicone oil or not. In total, around 500 capacitance measurements were retrieved from the albumin and free hemoglobin group, respectively. The mean increase in capacitance in the albumin 3 g/L group was 257 ± 100 pF without and 105 ± 30 pF with silicone oil, respectively, during 24 h. After ten hours of recording, differences between the two albumin groups reached statistical significance. For the free hemoglobin groups (0.01 g/L), the mean increase in capacitance was 190 ± 170 pF with silicone oil, and 324 ± 80 pF without, with a significant difference between the groups after 20 h and onwards. Coating of the capacitance measurement membrane of the automatic urinometer by albumin or free hemoglobin was significantly decreased by silicone oil, prolonging the functionality of the device.

RevDate: 2021-01-12

Du Y, Yu D, Wang X, et al (2021)

Achieving simultaneous nitritation, anammox and denitrification (SNAD) in an integrated fixed-biofilm activated sludge (IFAS) reactor: Quickly culturing self-generated anammox bacteria.

The Science of the total environment, 768:144446 pii:S0048-9697(20)37977-8 [Epub ahead of print].

In this study, by inoculating nitritation suspended sludge, simultaneous nitritation, anammox and denitrification (SNAD) was established quickly in an integrated fixed-biofilm activated sludge (IFAS) reactor to treat high-ammonia municipal wastewater. Results showed that, deep-level total nitrogen and chemical oxygen demand removal efficiencies (92.8% and 78.8%, respectively) were achieved, and their effluent concentrations were 13.2 and 39.3 mg/L, respectively. Excess generation of nitrate was once occurred under continuous aerobic condition, but it could be solved by suppressing nitrite oxidizing bacteria activity stably via switching to intermittent aeration mode (alternate 7 min of aerobic and 21 min of anoxic) and rising influent ammonium concentration temporarily (lasted 31 days). High-throughput sequencing analysis revealed that, Candidatus_Brocadia, as dominant anammox bacteria, was self-generated in flocs (2.93%) but mainly biofilm (7.67%), whereas uncultured_f_Nitrosomonadaceae as ammonia oxidizing bacteria was mainly found in flocs (2.4%). This work not only demonstrated that anammox bacteria could be self-generated and retained in the SNAD-IFAS system, but also suggested a promising application of the SNAD-IFAS in wastewater treatment plants.

RevDate: 2021-01-12

Alomary MN, MA Ansari (2021)

Proanthocyanins-capped biogenic TiO2 nanoparticles with enhanced penetration, antibacterial and ROS mediated inhibition of bacteria proliferation and biofilm formation: A comparative approach.

Chemistry (Weinheim an der Bergstrasse, Germany) [Epub ahead of print].

The biofunctionalized TiO2 NPs, having a size range of 18.42 ± 1.3 nm were synthesized employing single step approach employing Grape seed extract (GSE) mediated proanthocyanins (PACs) polyphenols. The present study purposes to examine the effect of PACs rich GSE corona on (i) the stability and dispersity of GSE-TiO 2 -NPs, their (ii) anti-proliferative and anti-biofilm efficacy and (iii) propensity of internalization and reactive oxygen species (ROS) generation in P. aeruginosa and S. saprophyticus strains. The state-of-the-art techniques were used to validate NPs formation. The comparative FTIR spectral analysis demonstrated that PACs linked functional -OH groups likely played a central role in Ti 4+ reduction, nucleation, formation and stability of GSE-TiO 2 -NPs. The TEM and ICP-MS analyses confirmed there was significantly (p < 0.05) enhanced intracellular uptake of GSE-TiO 2 -NPs in tested uropathogens as compare to bare TiO 2 -NPs. Correspondingly, compared to bare NPs, GSE-TiO 2 -NPs induced intracellular ROS formation that corresponded well with dose-dependent inhibitory patterns of cell proliferation and biofilm formation in both the tested strains. Overall, this study demonstrates that -OH rich PACs of GSE corona on biogenic TiO 2 -NPs maximized the functional stability, dispersity and propensity of penetration into planktonic cells and biofilm matrices; albeit, such unique merits warranted the GSE-TiO 2 -NPs as a novel, functionally stable and efficient antibacterial nanoformulation to combat with UTIs menace in clinical settings.

RevDate: 2021-01-12

Salisbury AM, Mullin M, Foulkes L, et al (2021)

The Ability of a Concentrated Surfactant Gel to Reduce an Aerobic, Anaerobic and Multispecies Bacterial Biofilm In Vitro.

Advances in experimental medicine and biology [Epub ahead of print].

Biofilm formation in wounds can lead to increased inflammation, infection and delayed wound healing. Additionally, biofilms show increased recalcitrance to antimicrobials compared to their planktonic counterparts making them difficult to manage and treat. Biofilms are frequently polymicrobial, consisting of aerobic and anaerobic bacteria, as well as fungi and yeasts. The aim of this study was to evaluate the effects of a concentrated surfactant gel with antibacterial preservative agents (CSG) against wound relevant opportunistic pathogens, including an aerobic biofilm, anaerobic biofilm and multispecies biofilm. The CSG was added to a 48 h anaerobic biofilm of Bacteroides fragilis, a 24 h multispecies biofilm of Acinetobacter baumannii, Staphylococcus aureus and Staphylococcus epidermidis and a 24 h biofilm of Pseudomonas aeruginosa grown in an in vitro wound relevant environment. Following a contact time of 24 h with the CSG, the bacterial cell density of the biofilms was reduced by 2-4 log in comparison to an untreated control. The results demonstrate the ability of the CSG to disrupt wound relevant biofilms and support the use of the CSG in the clinic to treat wounds caused by biofilm related infections.

RevDate: 2021-01-12

Bamunuarachchi NI, Khan F, YM Kim (2021)

Bactericidal activity of Sargassum aquifolium (Turner) C. Agardh against Gram-positive and Gram-negative biofilm-forming pathogenic bacteria.

Current pharmaceutical biotechnology pii:CPB-EPUB-113165 [Epub ahead of print].

AIM: To study the bactericidal activity of crude ethanolic extract and fractionations obtained from Sargassum aquifolium (Turner) C. Agardh (brown algae) towards Gram-positive bacteria and Gram-negative biofilm-forming human pathogenic bacteria.

BACKGROUND: The increasing emergence of antibiotic-resistant bacteria in the hospital and community settings lead to the discovery of alternative strategies. Marine organisms are considered as one of the potential sources of the diverse bioactive molecules against several biological activities. Hence, the algae especially the marine brown algae were selected to evaluate its antibacterial activities towards biofilm-forming human pathogenic bacteria.

OBJECTIVE: To restrain the drug-resistant ability of pathogenic bacteria, we have checked the extract of Sargassum aquifolium (Turner) C. Agardh (Phyophyceae) for the concerned bioactive compounds.

METHODS: Antibacterial activity towards both Gram-positive and Gram-negative bacteria was evaluated using disk diffusion and broth microdilution assays. Furthermore, the active compound present in the extracts were also identified using gaschromatography-mass spectroscopy (GC-MS).

RESULTS: A total of 21 bioactive compounds were identified using GC-MS analysis with different chemical natures. The crude ethanolic extraction was fractionated sequentially according to the eluotropic series from less to extreme polar. The highest zone of inhibition was recorded for ethanolic extract on Listeria monocytogenes with a value of 38.00±0.17 mm and the lowest was 10.67±0.06 mm for ethyl acetate fraction on Pseudomonas aeruginosa. Ethyl acetate fractionate showed a higher effectivity than other fractionations. 256 µg/mL MIC value was recorded against Staphylococcus aureus and L. monocytogenes and 512 µg/mL against Escherichia coli and P. aeruginosa. Its ethanolic extract also showed synergism with oxytetracycline on S. aureus, L. monocytogenes, and E. coli. Furthermore, the same extracts also showed synergism with tetracycline on E. coli and with erythromycin on P. aeruginosa.

CONCLUSION: The present study reports the antibacterial activity of the S. aquifolium (Turner) C. Agardh extracts against human pathogenic bacteria. Furthermore, it also predicts the synergistic activity of selected antibiotic combinations against both selected Gram-positive and Gram-negative pathogenic bacteria.

RevDate: 2021-01-12

Gómez-Molero E, De-la-Pinta I, Fernández-Pereira J, et al (2021)

Candida parapsilosis Colony Morphotype Forecasts Biofilm Formation of Clinical Isolates.

Journal of fungi (Basel, Switzerland), 7(1): pii:jof7010033.

Candida parapsilosis is a frequent cause of fungal bloodstream infections, especially in critically ill neonates or immunocompromised patients. Due to the formation of biofilms, the use of indwelling catheters and other medical devices increases the risk of infection and complicates treatment, as cells embedded in biofilms display reduced drug susceptibility. Therefore, biofilm formation may be a significant clinical parameter, guiding downstream therapeutic choices. Here, we phenotypically characterized 120 selected isolates out of a prospective collection of 215 clinical C. parapsilosis isolates, determining biofilm formation, major emerging colony morphotype, and antifungal drug susceptibility of the isolates and their biofilms. In our isolate set, increased biofilm formation capacity was independent of body site of isolation and not predictable using standard or modified European Committee on Antimicrobial Susceptibility Testing (EUCAST) drug susceptibility testing protocols. In contrast, biofilm formation was strongly correlated with the appearance of non-smooth colony morphotypes and invasiveness into agar plates. Our data suggest that the observation of non-smooth colony morphotypes in cultures of C. parapsilosis may help as an indicator to consider the initiation of anti-biofilm-active therapy, such as the switch from azole- to echinocandin- or polyene-based strategies, especially in case of infections by potent biofilm-forming strains.

RevDate: 2021-01-12

Benzaid C, Belmadani A, Tichati L, et al (2021)

Effect of Citrus aurantium L. Essential Oil on Streptococcus mutans Growth, Biofilm Formation and Virulent Genes Expression.

Antibiotics (Basel, Switzerland), 10(1): pii:antibiotics10010054.

In an oral cavity, dental caries, periodontal disease, and endodontic lesions are caused by well-known bacterial and fungal pathogens. Essential oils (EOs) have demonstrated antimicrobial activity suggesting their use for oral hygiene. The goal of this study was to evaluate the interaction of bitter orange flower (Citrus aurantium L.) essential oil with cariogenic bacteria Streptococcus mutans and human gingival epithelial cells. After extraction, the chemical composition of the essential oil was analyzed by gas chromatography, and its antimicrobial activity was evaluated against the growth and the expression of virulent genes in S. mutans. Finally, the effects of this essential oil on human gingival epithelial cell adhesion and growth were assessed using cell adhesion and proliferation assays. We showed that the major constituents of the tested essential oil were limonene, linalool, and β-ocimene. The essential oil reduced the growth of S. mutans, and decreased expression of comC, comD, comE, gtfB, gtfC, and gbpB genes. It should, however, be noted that essential oil at high concentration was toxic to gingival epithelial cells. Overall, this study suggests that C. aurantium L. essential oil could be used to prevent/control oral infections.

RevDate: 2021-01-12

Ma L, Xu Y, Xu X, et al (2021)

Application of biomimetic double-layer biofilm stent in arthroscopic rotator cuff repair: A protocol of randomized controlled trial.

Medicine, 100(1):e23960.

BACKGROUND: Rotator cuff injury is the most common cause of shoulder dysfunction. Despite the continuous advancement of surgical techniques, the incidence of re-tearing after rotator cuff repair is still high. The main reason is that it is difficult to reconstruct the normal tendon bone interface and the process is slow, and the application of tissue engineering technology can promote tendon and bone healing. This study will evaluate the effect of the bionic double membrane stent on the rotator cuff healing after arthroscopic rotator cuff repair.

METHODS: This is a prospective randomized controlled trial to study the effect of biomimetic double-layer biofilm stent on rotator cuff healing. Approved by the clinical research ethics committee of our hospital. The patients were randomly divided into 1 of 2 treatment options: (A) a biomimetic double-layer biofilm stent group and (B) a non-bionic dual-layer biofilm stent group. Observation indicators include: visual analog scale score, University of California Los Angeles score, American Shoulder & Elbow Surgeons score and Constant-Murley score. Data were analyzed using the statistical software package SPSS version 16.0 (Chicago, IL).

DISCUSSION: This study will evaluate and evaluate the effect of the bionic double-layer membrane stent on the rotator cuff healing after arthroscopic rotator cuff repair. The results of this experiment will provide new treatment ideas for promoting rotator cuff tendon bone healing.

OSF REGISTRATION NUMBER: DOI 10.17605/OSF.IO/FWKD6.

RevDate: 2021-01-12

Cox SC, Jamshidi P, Eisenstein NM, et al (2017)

Surface Finish has a Critical Influence on Biofilm Formation and Mammalian Cell Attachment to Additively Manufactured Prosthetics.

ACS biomaterials science & engineering, 3(8):1616-1626.

Additive manufacturing (AM) technologies enable greater geometrical design freedom compared with subtractive processes. This flexibility has been used to manufacture patient-matched implants. Although the advantages of AM are clear, the optimization at each process stage is often understated. Here we demonstrate that surface finishing of selective laser melted (SLM) implants significantly alters topography, which has implications for cellular and biofilm adhesion. Hot isostatic pressing of as-fabricated Ti-6Al-4V implants was shown to reduce porosity (1.04 to 0.02%) and surface roughness (34 ± 8 to 22 ± 3 μm). Despite these surface changes, preosteoblasts exhibited a similar viability and proliferation after 7 days of culture. Contrastingly, sandblasting and polishing significantly reduced cellular activity and increased cytotoxicity. Bacterial specimens (Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa) adhered more homogeneously to sandblasted implants compared with other treatments. This suggests that sandblasting may place the implant at risk of infection and reduce the strength of interaction with the surrounding soft tissues. The ability to tune the adhesion of cells to additively manufactured Ti-6Al-4V implants using postprocessing methods was demonstrated. Because the degree of tissue integration required of implants is application specific, these methods may be useful to tailor osseointegration. However, surface competition between mammalian and bacterial cells remains a challenge.

RevDate: 2021-01-11

Li N, Li X, Zhang HJ, et al (2020)

Microbial community and antibiotic resistance genes of biofilm on pipes and their interactions in domestic hot water system.

The Science of the total environment, 767:144364 pii:S0048-9697(20)37895-5 [Epub ahead of print].

This study aimed to explore the dynamics of microbial communities and antibiotic resistance genes (ARGs) during biofilm formation on polypropylene random (PPR), polyvinyl chloride and stainless steel pipes in domestic hot water system (DHWS), as well as their interactions. Full-scale classification was used to divide abundant and rare genera with 0.1% and 1% as the thresholds. The biofilm community structure presented a temporal pattern, which was mainly determined by conditionally rare or abundant taxa (CRAT) and conditionally rare taxa (CRT). The dynamics of microbial community during biofilm formation were observed, and the effect of pipe material on conditionally abundant taxa (CAT) and CRAT was greater than CRT and rare taxa (RT). CRAT showed the most complex internal associations and were identified as the core taxa. Notably, CRT and RT with low relative abundance, also played an important role in the network. For potential pathogens, 17 genera were identified in this study, and their total relative abundance was the highest (3.6-28.9%) in PPR samples. Enterococcus of CRAT was the dominant potential pathogen in young biofilms. There were 36 more co-exclusion patterns (140) observed between potential pathogens and nonpathogenic bacteria than co-occurrence (104). A total of 38 ARGs were predicted, and 109 negative and 165 positive correlations were detected between them. Some potential pathogens (Escherichia/Shigella and Burkholderia) and nonpathogenic bacteria (Meiothermus and Sphingopyxis) were identified as the possible hosts of ARGs. This study is helpful for a comprehensive understanding of the biofilm microbial community and ARGs, and provides a reference for the management and biosafety guarantee of newly-built DHWS.

RevDate: 2021-01-11

Zhou Y, Li R, Guo B, et al (2021)

Lumen air pressure (LAP) affecting greywater treatment in an oxygen-based membrane biofilm reactor (O2-MBfR).

Chemosphere, 270:129541 pii:S0045-6535(21)00011-4 [Epub ahead of print].

Several technologies have been employed to treat greywater (GW) for domestic use. Aerobic biological treatment has achieved high efficiency, the main cost being the necessary source of oxygen (O2). This study explores the effects of lumen air pressure (LAP) on reactor performance and microbial community succession in an O2-based membrane biofilm reactor (O2-MBfR) treating GW. At high LAP (≥0.8 psi), the dissolved oxygen (DO) concentration inside the reactor was higher than 0.38 ± 0.02 mg/L, leading to removal efficiencies of 90%, 98%, and 80%, of total chemical oxygen demand, total linear alkylbenzene sulfonate (LAS), and total nitrogen, respectively. Lower LAP (<0.8 psi) led to a decrease in DO inside the system, and a less effective GW treatment. Low O2 pressure decreased organic biodegradation and ammoniation, and caused LAS accumulation in the biofilm, leading to the solubilization of extracellular polymeric substances and cell lysis. Comprehensive consideration of reactor performance and energy input, DO inside the MBfR at 0.38 ± 0.02 mg/L could be selected as the optimized condition for GW treatment. Microbial community analyses results also revealed that improved LAP was favorable for the enrichment of LAS-biodegradation related genus (Pseudomonas, Parvibaculum, Magnetospirillum, Clostridium, Zoogloea, Dechloromonas and Mycobacterium), nitrifiers (Nitrosomonas and Sphingomonas) and facultative microorganisms (Dechloromonas, Flavobacterium, Pseudomonas, Aeromonas and Zoogloea) that can carry out denitrification under relatively high DO conditions (>0.38 mg/L), but led to the reduction of the relative abundance of heterotrophs (Acidovorax, Thermomonas, Brevundimonas and Enterobacter) that are more sensitive towards high DO conditions.

RevDate: 2021-01-11

Li H, Li Y, Guo J, et al (2021)

Effect of calcinated pyrite on simultaneous ammonia, nitrate and phosphorus removal in the BAF system and the Fe2+ regulatory mechanisms: electron transfer and biofilm properties.

Environmental research pii:S0013-9351(21)00002-5 [Epub ahead of print].

To efficiently remove nitrogen and phosphorus from secondary effluent with low values of COD/TN, a novel biological aerated filter (BAF) utilizing calcinated pyrite with a large specific surface area (SSA) and pore diameter (PD) was designed to address this challenge. From the perspective of nutrients removal performance, and the corresponding effluent total nitrogen (TN) and PO43--P in the calcinated pyrite autotrophic denitrification (CPAD) process decreased from 40.21 and 1.07 mg/L to 1.22 and 0.14 mg/L, respectively. Furthermore, the nutrients removal kinetics analysis showed that the CPAD and pyrite autotrophic denitrification (PAD) processes could be fitted with Half-order and Zero-order reactions via kinetics analysis, respectively, indicating that the TN removal performance of CPAD processes was better than that of the PAD process. Moreover, CPAD combined with sulfur autotrophic denitrification (SAD) processes was fitted by First-order reaction, and the TN removal performance was further enhanced over the CPAD process. From the perspective of microregulation, Fe2+ production in the PAD and CPAD processes could accelerate the electron transfer rate by increasing electron transport system activity (ETSA) and reducing electrochemical impedance spectroscopy (EIS). Moreover, Fe2+ stimulated microbes to produce more proteins (PN) and C10-HSL, which improved biofilm stability and interspecific communication processes. Notably, nitrifiers and autotrophic denitrifiers were simultaneously enriched via detection of high-throughput sequencing of 16S rRNA genes, which verified the feasibility of simultaneous nitrification and autotrophic denitrification. Therefore, BAF with calcinated pyrite and sulfur as composite fillers have a considerable advantage in nutrients removal.

RevDate: 2021-01-11

Arif M, Sharaf M, Samreen , et al (2021)

Chitosan-based nanoparticles as delivery-carrier for promising antimicrobial glycolipid biosurfactant to improve the eradication rate of Helicobacter pylori biofilm.

Journal of biomaterials science. Polymer edition [Epub ahead of print].

Driven by the need to find alternatives to control H. pylori infections, this work describes the development of chitosan-PMLA nanoparticulate systems as carriers for antimicrobial glycolipid. By using a simple ionic gelation method stable nanoparticle was obtained showing an encapsulation efficiency of 73.1 ± 1.3% and an average size of 217.0 ± 15.6 nm for rhamnolipids chitosan-PMLA nanoparticles (RL-CS-NPs). Glycolipid incorporation and particle size were correspondingly corroborated by FT-IR and TEM analysis. Rhamnolipids chitosan nanoparticles (RL-CS-NPs) presented the highest antimicrobial effect towards H. pylori (ATCC 26695) exhibiting a minimal inhibitory concentration of 132 µg/mL and a biofilm inhibition ability of 99%. Additionally, RL-CS-NPs did not interfere with human fibroblasts viability and proliferation under the tested conditions. The results revealed that the RL-CS-NPs were able to inhibit bacterial growth showing adequate cytocompatibility and might become, after additional studies, a valuable approach to fight H. pylori biofilm related-infections.

RevDate: 2021-01-11

Houshmandyar S, Eggleston IM, A Bolhuis (2021)

Biofilm-specific uptake of a 4-pyridone-based iron chelator by Pseudomonas aeruginosa.

Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine [Epub ahead of print].

Iron is an essential nutrient for virtually all microbes and limiting the concentration of available iron is a potential strategy to be used as an alternative to antibiotic treatment. In this study we analysed the antimicrobial activity of two chelators, specifically 3-hydroxy-1,2-dimethyl-4(1H)-pyridone (deferiprone, DFP), which is clinically approved for the treatment of iron overload disorders, and its 1,2-diethyl homologue, CP94. Both compounds showed moderate activity towards planktonically growing P. aeruginosa cells, and the mechanism of action of these chelators was indeed by limiting the amount of free iron. Surprisingly, the compounds behaved very differently when the cells were grown in biofilms. DFP also showed inhibitory effects on biofilm formation but in contrast, CP94 stimulated this process, in particular at high concentrations. We hypothesised that CP94 behaves as an iron carrier, which was confirmed by our observation that it had antimicrobial synergy with the toxic metals, gallium and copper. This suggests that P. aeruginosa produces a biofilm-specific transport protein that recognises CP94 but not the closely related compound DFP.

RevDate: 2021-01-11

Zimba S, Kumar TS, Mohan N, et al (2021)

Evaluation of various waste substrates for biofilm formation and subsequent use in aerobic packed-bed reactor for secondary treatment of domestic wastewater.

World journal of microbiology & biotechnology, 37(2):25.

Immobilization of bacterial cells on suitable substrates is of utmost importance in the secondary treatment of wastewater using fixed-film reactors. Therefore, screening of efficient and cheaper materials for bacterial surface immobilization was carried out. Eleven waste materials were used as substrates, packed in a column, and bacterial surface immobilization was carried out using cow dung slurry/MLSS mixture. All the chosen substrates were screened for bacterial immobilization/biofilm formation by standard bacterial enumeration technique. The substrate with the highest biofilm-forming ability was used for secondary treatment of raw domestic wastewater. The results showed that high-density polyethylene and aluminium foil sheets have poor immobilizing characteristics with 2.2 × 108 and 2.4 × 108 CFU/cm2 respectively, whereas jute fibres were observed to be the most efficient among the substrates with 5.1 × 1023 CFU/cm2. The column packed with jute fibres was used for wastewater treatment. Various physico-chemical parameters were analyzed before and after treatment and there was a significant reduction in major parameters after treatment. The bacteria-immobilized jute fibres showed maximum immobilization potential and were highly efficient in wastewater treatment, and therefore these findings offer immense promise in the synthesis of composite polymers for bacterial immobilization and subsequent secondary treatment.

RevDate: 2021-01-11

Brilhante RSN, Paixão GC, Pereira VS, et al (2021)

Atypical chlamydoconidium-producing Trichophyton tonsurans strains from Ceará State, Northeast Brazil: investigation of taxonomy by phylogenetic analysis and biofilm susceptibility.

Microbiology (Reading, England) [Epub ahead of print].

Chlamydoconidium-producing Trichophyton tonsurans strains isolated in Northeastern Brazil have morphological features different from the classic description of this dermatophyte species. This study investigated the phylogenetic relationship of chlamydoconidium-producing T. tonsurans strains isolated in Northeastern Brazil. Also, the effect of terbinafine and farnesol on mature biofilms of T. tonsurans strains was evaluated. The mass spectra of T. tonsurans strains were investigated by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). The ITS and LSU loci regions of rDNA and the partial β-tubulin gene were sequenced and the phylogenetic tree was analysed. The effects of terbinafine and farnesol on mature T. tonsurans biofilms were evaluated through the analysis of metabolic activity, quantification of biomass and observation by scanning electron microscopy. MALDI-TOF MS spectra of the chlamydoconidium-producing T. tonsurans strains differed from the spectrum of the control strain (ATCC 28942), presenting an intense ion peak at m/z 4155 Da. Phylogenetic tree analysis showed that the chlamydoconidium-producing strains isolated in Northeastern Brazil are allocated to a single cluster, differing from strains isolated from other countries. As for mature T. tonsurans biofilms, farnesol reduced biomass and metabolic activity by 64.4 and 65.9 %, respectively, while terbinafine reduced the biomass by 66.5 % and the metabolic activity by 69 %. Atypical morphological characteristics presented by chlamydoconidium-producing T. tonsurans strains result from phenotypic plasticity, possibly for adaptation to environmental stressors. Also, farnesol had inhibitory activity against T. tonsurans biofilms, demonstrating this substance can be explored for development of promising anti-biofilm drugs against dermatophytes.

RevDate: 2021-01-11

Ke CL, Liao YT, CH Lin (2021)

MSS2 maintains mitochondrial function and is required for chitosan resistance, invasive growth, biofilm formation and virulence in Candida albicans.

Virulence, 12(1):281-297.

Candida albicans is the most prevalent fungal pathogen in humans, particularly in immunocompromised patients. In this study, by screening a C. albicans mutant library, we first identified that the MSS2 gene, an ortholog of Saccharomyces cerevisiae MSS2 required for mitochondrial respiration, mediates chitosan resistance. Upon treatment with 0.2% chitosan, the growth of mss2Δ strains was strikingly impaired, and MSS2 expression was significantly repressed by chitosan. Furthermore, mss2Δ strains exhibited slow growth on medium supplemented with glycerol as the sole carbon source. Similar to the chitosan-treated wild-type strain, the mss2Δ strain exhibited a significantly impaired ATP production ability. These data suggest that an antifungal mechanism of chitosan against C. albicans acts by inhibiting MSS2 gene expression, leading to repression of mitochondrial function. Normal respiratory function is suggested to be required for fungal virulence. Interestingly, the mss2Δ mutant strains exhibited significantly impaired invasive ability in vitro and ex vivo but retained normal hyphal development ability in liquid medium. Furthermore, the MSS2 deletion strains could not form robust biofilms and exhibited significantly reduced virulence. Collectively, these results demonstrated that the antifungal effect of chitosan against C. albicans is mediated via inhibition of mitochondrial biogenesis. These data may provide another strategy for antifungal drug development via inhibition of fungal mitochondria.

RevDate: 2021-01-11

Eick S (2021)

Biofilm Models for the Evaluation of Dental Treatment.

Monographs in oral science, 29:38-52.

When analyzing the activity of antimicrobial agents, it should be considered that microorganisms mainly occur in biofilms. Data obtained for planktonic bacteria cannot be transferred non-critically to biofilms. Biofilm models should consider both the relevant microorganisms and the conditions present in the environment. The selection of the model depends on the question to be answered. In dentistry, single species, multispecies, or microcosms originating from saliva or dental biofilm are used to culture biofilms. Microorganism selection depends on the focus of the study, for example caries biofilms mostly include Streptococcus mutans, an endodontic biofilm consists mostly of Enterococcus faecalis, and defined anaerobes are used in periodontal/peri-implant biofilms. In contrast to single-species biofilm models in medicine, where the lowest concentration of the antimicrobial that kills microorganisms is measured, the common analyzed variables are counts of colony-forming units or the percentage of dead bacteria determined by confocal laser scanning microscopy after applying a differentiating stain. All the models are helpful to evaluate new antimicrobial treatment options. Conclusions regarding the antimicrobial activity tendency of the therapeutics can be drawn. However, there are limitations of the model and ultimately a new therapy has to be proven in randomized controlled clinical trials.

RevDate: 2021-01-11

Jentsch HFR (2021)

Actual Concepts for Individual Interdental Biofilm Removal.

Monographs in oral science, 29:74-79.

The intraoral biofilm requires mechanical removal due to its physical properties. When exposed to the biofilm, interdental areas need special devices to be used. The most effective ones and the first choice are interdental brushes. However, they may not be adequate in the case of very narrow interdental spaces. Despite the difficulties in handling, dental floss may have some advantage in subgingival cleaning. Data are present for gingivitis and periodontitis, but almost no information has been published on gingivally healthy individuals. With respect to interdental caries there is evidence that floss only has a protective value when used professionally and without sufficient fluoridation. There are no such data available on interdental brushes.

RevDate: 2021-01-11

Bastendorf KD, Strafela-Bastendorf N, A Lussi (2021)

Mechanical Removal of the Biofilm: Is the Curette Still the Gold Standard?.

Monographs in oral science, 29:105-118.

The goal of modern periodontal therapy, both during the initial stages and during maintenance, is to create biologically acceptable tooth surfaces through sub- and supragingival cleaning, which enables binding of the connective tissue to the greatest extent possible. In past centuries, the focus of periodontal treatment was on the removal of the supposed cause of periodontal disease, the supra- and supragingival calculus and "infected" root cementum. The findings on the importance of biofilm1 (plaque) and the endogenous responses to biofilm metabolism have shifted the therapeutic focus to elimination of the biofilm. The importance of avoiding injury to the hard and soft dental tissue is nowadays of upmost importance. For classical scaling and root planing to remove mineralized deposits and "infected" cementum, only hand instruments were available in the past. The regular, long-term use of these tools is associated with changes in the hard and soft tooth tissues, and with pain and sensitivity experienced by the patient during and after treatment. Modern root-surface debridement primarily uses ultrasound systems to remove hard mineralized deposits. For biofilm management, air polishing devices with low-abrasive powders are increasingly gaining acceptance. With this new technology, biofilm management can now be performed much more effectively and efficiently, using materials more sparingly; this also causes less pain and discomfort for patients during and after treatment, and less fatigue for practitioners. The modern systems allow gentle, optimal biofilm management, whereas the traditional hand instruments (curettes, scalers) and classic rotating instruments used for polishing do not. Current knowledge suggests that these instruments are not best suited for biofilm management.

RevDate: 2021-01-11

Arweiler NB (2021)

Oral Mouth Rinses against Supragingival Biofilm and Gingival Inflammation.

Monographs in oral science, 29:91-97.

Caries and inflammatory periodontal diseases have a high prevalence worldwide. Although improvements in oral health status in our patients have been shown, there is still an increased demand for preventive measurements - especially in view of the systemic influence of the chronic disease periodontitis. The main focus of such measurements lies on an optimal biofilm management which can be divided into professional biofilm management and home care measurements. Since home care mechanical measurements such as toothbrushing and interdental cleaning are often insufficient or not on a regular basis, they can be supported by antibacterial agents which are able to inhibit or kill any oral microorganisms that remain. Besides a proven effect on plaque bacteria and gingival inflammation, agents should have a high substantivity in the oral cavity that outlast the short rinsing period. This chapter aims to present the background and rationale of using antibacterial mouth rinses, their common agents, to show sensible indications, and to evaluate the scientific evidence of their additional effect over toothbrushing alone.

RevDate: 2021-01-11

Eick S, A Lussi (2021)

Arginine: A Weapon against Cariogenic Biofilm?.

Monographs in oral science, 29:80-90.

Untreated dental caries is the most prevalent disease worldwide. Development of caries is associated with the intake of sugar. The microorganisms utilize the sugar and create an acidic environment, which results in mineral loss. The appropriate use of fluoride is associated with a decline of caries. Another approach in preventing caries might be the increase of pH in dental plaque. During recent years, arginine has increasingly become the focus of interest. This is based on the fact that certain streptococci possess an arginine deiminase system (ADS) which metabolizes free arginine. In vivo, the incidence of caries was inversely correlated with ADS activity in saliva and dental plaque. ADS is highly active in Streptococcus gordonii and S. sanguinis, but is absent in S. sobrinus and S. mutans. In the presence of 1.5% L-arginine, S. gordonii and S. sanguinis, but not S. mutans and S. sobrinus, synthesize the metabolite citrulline and increase the pH of the environment.In defined multispecies biofilms consisting of ADS-positive and ADS-negative streptococci, supplementation with 1.5% arginine suppressed the growth of ADS-negative by favoring ADS-positive streptococci together with an increase in the pH of the environment. Evaluating the influence of daily manual removal of the biofilm in vitro by brushing with a commercial toothpaste containing fluoride and arginine resulted in less surface microhardness even when compared with a toothpaste with fluoride only. Recent studies clinically investigated the effect of using an arginine-containing dentifrice and reported a decrease of DMFS by about 10-20%.

RevDate: 2021-01-11

Katagiri H, Stuck NJ, Arakawa I, et al (2021)

In vitro Activity of Oral Health Care Products on Candida Biofilm Formation.

Monographs in oral science, 29:214-226.

The activity of mouthwash ingredients used in daily oral care (chlorhexidine digluconate, benzalkonium chloride, povidone iodine solution, tea tree oil) and of nystatin was evaluated not only on planktonic Candida albicans or C. glabrata, but also on the inhibition of biofilm formation. A microbroth dilution technique was used to determine the minimum inhibitory concentration of the substances against two laboratory strains and seven clinical isolates. Furthermore, a potential inhibition of biofilm formation of C. albicans or C. glabrata (single-species biofilm or mixed with two oral bacteria) was assessed. The results showed an activity of all tested substances against all C. albicans and C. glabratastrains. In the biofilm assays, a concentration-dependent effect of the substances was visible. However, a low concentration of povidone iodine solution and in particular of benzalkonium chloride seemed to increase the virulence of C. albicans. Most test substances affected both bacteria and yeasts in the mixed biofilms, only nystatin predominately reduced the yeasts. In conclusion, nystatin might be the drug of choice when exclusively preventing the colonization of Candida sp. in biofilms. The alternatives, benzalkonium chloride, povidone iodine solution, and tea tree oil, should be investigated further.

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In the early 1990's, Robert Robbins was a faculty member at Johns Hopkins, where he directed the informatics core of GDB — the human gene-mapping database of the international human genome project. To share papers with colleagues around the world, he set up a small paper-sharing section on his personal web page. This small project evolved into The Electronic Scholarly Publishing Project.

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In 1995, Robbins became the VP/IT of the Fred Hutchinson Cancer Research Center in Seattle, WA. Soon after arriving in Seattle, Robbins secured funding, through the ELSI component of the US Human Genome Project, to create the original ESP.ORG web site, with the formal goal of providing free, world-wide access to the literature of classical genetics.

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This is a must read book for anyone with an interest in invasion biology. The full title of the book lays out the author's premise — The New Wild: Why Invasive Species Will Be Nature's Salvation. Not only is species movement not bad for ecosystems, it is the way that ecosystems respond to perturbation — it is the way ecosystems heal. Even if you are one of those who is absolutely convinced that invasive species are actually "a blight, pollution, an epidemic, or a cancer on nature", you should read this book to clarify your own thinking. True scientific understanding never comes from just interacting with those with whom you already agree. R. Robbins

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Papers in Classical Genetics

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Along with papers on classical genetics, ESP offers a collection of full-text digital books, including many works by Darwin (and even a collection of poetry — Chicago Poems by Carl Sandburg).

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Selected Bibliographies

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