Biofilm-forming Strains Research Articles

Ultrastructural changes in biofilm forms of staphylococci cultivated in a mixed culture with lactobacilli

The capacity of opportunistic bacteria for biofilm formation plays an important role in the development of chronic inflammatory processes, which are difficult to treat. To improve antimicrobial therapy methods, the influence of lactobacilli on the ultrastructure of biofilm-forming clinical strains of staphylococci when co-cultured was investigated. 5 biofilm-forming clinical strains of S. aureus from the skin of acne vulgaris patients (n = 24) were isolated. Using transmission electron microscopy (TEM) the morphological changes of S. aureus cells in the mixed culture with standard strains of Lactobacillus plantarum 8P-A3 and clinical strains of L. fermentum (n = 4) were studied. It was found that in 48 hours after the inoculation on the medium of samples of mixed cultures of L. plantarum 8P-A3 and S. aureus growth of staphylococci was not revealed. Only in some cases of mixed cultures of L. fermentum and biofilm-forming staphylococci was growth of S. aureus obtained. In electron diffraction patterns of control samples of 24-hour staphylococcal monocultures and 48-hour lactobacilli monocultures, natural development of the population at the cellular level was observed. Destructive changes under the influence of lactobacilli (probiotic and clinical strains) were detected in all ultrathin sections of the cells of biofilm-forming and planktonic staphylococci. Significant destructive changes in the cell wall of the staphylococci were observed: thickening, obtaining of irregular form, detachment of the cytoplasmic membrane, the complete destruction of the peptidoglycan layer and the emergence of "shadow cells". On all electron diffraction patterns fibrillar-threadlike structures of DNA could not be observed, but in some cases mesosome-like formations were poorly contrasted. It was established that the surface S-layer of lactobacilli was expressed on a significantly larger scale in the mixed culture with staphylococci. In mixed culture of clinical strains of lactobacilli with biofilm form of S. aureus, staphylococcal cells could be found in a dormant state. Thanks to an experimental model of biofilm in a mixed culture, the development of destructive changes of staphylococci under the influence of the lactobacilli both on the morphological and at the population levels has been assessed. The results obtained can be used in improving the schemes of complex antimicrobial therapy of pyoinflammatory processes with the use of biological preparations, which are composed of lactobacilli, including those in the form of local application.

ЧУТЛИВІСТЬ ДО АНТИБІОТИКІВ ПЛІВКОУТВОРЮВАЛЬНОЇ МІКРОФЛОРИ ВОГНЕПАЛЬНИХ РАН

Натепер залишається неясним, чи існує прямий зв’язок між формуванням біологічної плівки і резистентністю до антибіотиків мікроорганізмів. У даному дослідженні ми прагнули вивчити взаємозв’язок між цими властивостями у клінічних ізолятів бактерій.Мікроорганізми були виділені з вогнепальних поранень протягом 2014 р. Здатність до формування біоплівок визначали методом фарбування кристалічним фіолетовим. МБсК, МБцК, мінімальну концентрацію, що приводить до ерадикації біоплівки (МЕбК), амікацину, цефтріаксону, цефоперазон/сульбактаму, ципрофлоксацину, меропенему, гатефлоксацину, левофлоксацину визначали методом серійних розведень.Штами, що виявляли чутливість до антибіотиків у планктонній формі, показали високу стійкість при формуванні біоплівки. МЕбК антибіотиків для штамів, що сформували біоплівку, сягала понад 500 мгк/мл, що в сотні разів перевищує клінічно досяжні концентрації. Кореляційний зв’язок між стійкістю до антибіотиків і здатністю до біоплівкоутворення штамів A. baumannii був різнобічним: для меронему r = –0,62, для цефоперазону з клавулановою кислотою r = +0,62, для амікацину r = +0,84. Штами P. aeruginosa також виявили різноспрямований зв’язок між досліджуваними властивостями. Можна припустити, що формування біоплівки і стійкість до антибіотиків діють як окремі механізми, що забезпечують краще виживання бактерій, особливо ізолятів зі слабким рівнем резистентності до антибіотиків.

Biofilm formation by Aeromonas strains under food-related environmental stress conditions

Aeromonas, important human and fish pathogens, can form biofilm on food and food-contact surfaces that may act as a source of cross-contamination in the food-processing facilities. An investigation was undertaken to evaluate the impact of various food-related conditions (media composition, temperature, pH, salt, and food preservatives) on the biofilm formation by 10 different Aeromonas strains, belonging to six species, using polystyrene microtiter plate-based crystal-violet assay. These strains were vastly diverse in their biofilm forming abilities with the majority of them producing weak biofilm in TSB and M9 minimal medium. Among various conditions, majority of the strains formed the highest biofilm at low temperature (10°C) and acidic condition (pH 5). Biofilm formation for most of the strains reduced with an increase in NaCl concentration. The results indicate that various abiotic stresses encountered in food environment affect the production of biofilm in Aeromonas strains and is mainly a strain-specific phenomenon. Practical applications The present study reports the biofilm formation by Aeromonas species under different food-related environmental stress conditions. It will help food processors and regulators to optimize prohibitive measures to prevent biofilm formation and reduce the health risks related to biofilm-forming Aeromonas strains.

Quantifying Biofilm Formation of <i>Sinorhizobium meliloti</i> Bacterial Strains in Microfluidic Platforms by Measuring the Diffusion Coefficient of Polystyrene Beads

Though the majority of bacteria can form structured communities known as biofilms, mutations can cause bacterial strains to vary in their ability to form a biofilm. In this study, the apparent diffusion coefficient of polystyrene microspheres 0.29 μm in diameter, which were executing Brownian motion inside bacterial colonies, was used as a quantitative parameter of the ability of a strain to form a biofilm and of the biofilm development. The study was performed using five Sinorhizobium meliloti strains, the biofilm-forming strains Rm8530 expR+, Rm8530 exoY, and Rm9034 expG, and the non-biofilm forming strains Rm1021 and Rm9030-2 expA1. The green fluorescent beads were placed with each strain in a separate channel of a microfluidic device. Thus, as the bacterial colonies grew under identical conditions over a 4-day period, the motion of the fluorescent microspheres was recorded and the diffusion coefficients were measured every 24 hours via particle tracking algorithms. It was found that each strain displayed a unique pattern of change in diffusion coefficient over time. Also, for a given biofilm-forming strain, there was a clear correlation between the value of the diffusion coefficient and the appearance and motility of the bacterial community. Thus, the diffusion coefficient can be used to identify different S. meliloti strains, and for the biofilm-forming strains, it is also a quantitative indicator of the stage of biofilm development.

Quantification of Chlorophyll as a Proxy for Biofilm Formation in the Cyanobacterium Synechococcus elongatus

A self-suppression mechanism of biofilm development in the cyanobacterium Synechococcus elongatus PCC 7942 was recently reported. These studies required quantification of biofilms formed by mutants impaired in the biofilm-inhibitory process. Here we describe in detail the use of chlorophyll measurements as a proxy for biomass accumulation in sessile and planktonic cells of biofilm-forming strains. These measurements allow quantification of the total biomass as estimated by chlorophyll level and representation of the extent of biofilm formation by depicting the relative fraction of chlorophyll in planktonic cells.

Monitoring of biofilm aging in a Sphingomonas sp. strain from public drinking water sites through changes in capacitance

ABSTRACTThis study reports the applicability of a capacitance-based technique for evaluating the biofilm progression of Sphingomonas sp. One hundred and forty isolates of Sphingomonas were screened from public drinking water sites, and one potential strain with biofilm-forming ability was used for the study. The biofilm production by this strain was established in microtiter plates and aluminum coupons. The standard biofilm-forming strain Sphingomonas terrae MTCC 7766 was used for comparison. Changes in biofilm were analyzed by energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscope (SEM). Capacitance values were measured at 1, 100 and 200 kHz frequency; however, 1 kHz was selected since resulted in reproducible values, which could be correlated to biofilm age measured as dry weight over a time of 96 h (4 days) depicting the biofilm growth/progression over time. The EDX, SEM and capacitance values obtained in parallel indicated the related physiological profile usually displayed by biofilms upon growth, suggesting authenticity to the observed capacitance profile. The results of this study demonstrated the feasibility of a capacitance-based method for analyzing biofilm development/progression by Sphingomonas sp. and suggested a simple approach for developing an online system to detect biofilms by this opportunistic pathogen of concern in drinking water.

The graphene oxide and chitosan biopolymer loads TiO2 for antibacterial and preservative research

Microorganism breeding is a known cause of food spoilage and disease transmission. Aspergillus niger (A. niger) and Bacillus subtilis (B. subtilis) are examples of microorganisms that cause deterioration of fresh fruits and vegetables during storage, which can be a serious threat to human health. In this work, we synthesized a self-assembled film of graphene oxide (GO) and chitosan (CS) biopolymers with titanium dioxide (TiO2) nanoparticles embedded in its surface. We then characterized its antibacterial and preservative properties. We found that these non-cytotoxic nanometer-scale films, especially when the ratio of graphene oxide, chitosan and titanium dioxide nanoparticles in the nanocomposites is 1:20:4, exhibited high antibacterial activity against the biofilm-forming strains A. niger and B. subtilis. The preservation capacity of the nanocomposites was evaluated by enzymatic experiments. The nanocomposites did not show any cytotoxicity against mammalian somatic cells and plant cells. Altogether, this work demonstrated that the nanocomposites disrupted microbial film formation while avoiding internalization by animal and plant cells. Due to their selectivity and safety, these nanocomposites demonstrate potential as antimicrobial coatings for food preservation.

Antagonistic effects of biofilm-forming bacterial strains co-inoculated with blood disease pathogenic strain, Ralstonia syzygii subspecies celebesensis in banana plants

A blood disease pathogenic strain, Ralstonia syzygii subspecies celebesensis was used to study the possible association of biofilm-forming bacteria with the development and severity of blood disease in banana plants. Therefore, the objective of this study was to determine the effects of mono-culture and co-culture inoculation of isolated biofilm-forming bacteria with the blood disease pathogen in banana pseudostems in glasshouse conditions. Putative biofilm-forming bacteria were isolated from an infected banana plant and were further identified using 16SrRNA sequencing. Four isolates, identified as Enterobacter hormaechei, Enterobacter cloacae, Kosakonia radicincitans and Klebsiella pneumoniae, were inoculated as a mono- and co-culture with R. syzygii subsp. celebesensis into 2 months old banana plants. The observation after the 8 weeks of post inoculation showed that plants which were co-inoculated with the pathogen and K. radicincitans, a biofilm-forming bacterium, were the most susceptible towards the infection. In contrast, plants under two treatments (which were co-inoculated with the pathogen and E. cloacae and the pathogen with E. hormaechei) were less susceptible towards the infection. This study revealed the antagonistic effects of two biofilm-forming strains which reduced the severity of infection caused by the pathogenic agent. Scanning electron micrographs of the cross section of plant rhizomes indicated the dissimilarity of adhesion and host colonization conditions of the pathogen in each infected plant from different treatments.

IL-10 plays an important role in the control of inflammation but not in the bacterial burden in S. epidermidis CNS catheter infection.

BackgroundShunt infection is a frequent and serious complication in the surgical treatment in hydrocephalus. Previous studies have shown an attenuated immune response to these biofilm-mediated infections. We proposed that IL-10 reduces the inflammatory response to Staphylococcus epidermidis (S. epidermidis) CNS catheter infection.MethodsIn this study, a murine model of catheter-associated S. epidermidis biofilm infection in the CNS was generated based on a well-established similar model for S. aureus. The catheters were pre-coated with a clinically derived biofilm-forming strain of S. epidermidis (strain 1457) which were then stereotactically implanted into the lateral left ventricle of 8-week-old C57BL/6 and IL-10 knockout (IL-10 knockout) mice. Bacterial titers as well as cytokine and chemokine levels were measured at days 3, 5, 7, and 10 in mice implanted with sterile and S. epidermidis-coated catheters.ResultsCultures demonstrated a catheter-associated and parenchymal infection that persisted through 10 days following infection. Cytokine analysis of the tissue surrounding the catheters revealed greater levels of IL-10, an anti-inflammatory cytokine, in the infected group compared to the sterile. In IL-10 KO mice, we noted no change in bacterial burdens, showing that IL-10 is not needed to control the infection in a CNS catheter infection model. However, IL-10 KO mice had increased levels of pro-inflammatory mediators in the tissues immediately adjacent to the infected catheter, as well as an increase in weight loss.ConclusionsTogether our results indicate that IL-10 plays a key role in regulating the inflammatory response to CNS catheter infection but not in control of bacterial burdens. Therefore, IL-10 may be a useful therapeutic target for immune modulation in CNS catheter infection but this should be used in conjunction with antibiotic therapy for bacterial eradication.

MILIACINE INFLUENCE ON THE BIOFILM FORMATION OF BACTERIA

Aim. The comparative estimation of miliacine influence on the biofilm formation of bacteria. Materials and methods. The objects of investigation were the clinical isolates of Salmonella enteritidis (28), Salmonella typhimurium (24), Klebsiella pneumoniae (8), Pseudomonas aeruginosa (8) and reference strains of lactobacilli (5) and bifidobacteria (3). Miliacin was obtained from crystals of millet oil. Antibacterial activity of miliacin was detected by the method of serial dilutions. For investigation of biofilms miliacin in 100 and 50 mkg/ml concentrations was used. Miliacin was diluted in Twin-21. Biofilm formation was studied by method of O'Toole G.A., Kolter R. (1998) using spectrophotometer Elx 808 (BioTek, USA). The morphometry of biofilms was conducted by atomic force microscopy with the use of scanning probe microscope SMM-2000. Results. Miliacin and its solvent did not influence the growth of bacteria. Maximum sensivity of biofilms to miliacin was detected in K. pneumoniae and P. aeruginosa, minimal - in S. enteritidis. Miliacin did not influence the biofilm formation in strains of lactobacilli and bifidobacteria. Conclusion. Miliacin in addition to immunotropic activity, detected earlier, can inhibit the biofilms of opportunistic and pathogenic bacteria without influence on the biofilm formation of representatives of usual flora.

Purification and Evaluation of Polysaccharide Intercellular Adhesion (PIA) Antigen from Staphylococcus epidermidis.

The polysaccharide intercellular adhesin (PIA) confers major functional effects in biofilm formation, which bears an important role in the pathogenicity of Staphylococcus epidermidis. Following the identification of biofilm-forming strains by biochemical and molecular methods, isogenic strain was prepared and in vitro biofilm formation assay was performed consequently. By parallel analysis of both the PIA-positive and PIA-negative strains using size exclusion chromatography by Fast protein liquid chromatography (FPLC) method, the respective PIA was purified. Recovered PIA was examined using colorimetric and hemagglutination assays. Finally, the recovered PIA was analyzed using Fourier-transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy methods. By the parallel purification process and comparison of the obtained graphs from the FPLC detector, fractions near the void volume were determined as PIA. The colorimetric and hemagglutination assays were applied and the content of carbohydrates (hexose=620µg/ml, hexosamine=5700µg/ml and ketoses=170µg/ml) and hemagglutination titer (1:128) in recovered polysaccharide were determined. This study shows that PIA has a significant role in the biofilm formation in S. epidermidis strains. The recovered polysaccharide and its molecular weight were analyzed within the near void volume of the utilized column.

Biofilm formation of Campylobacter strains isolated from raw chickens and its reduction with DNase I treatment

Campylobacter is a well-known bacterial agent that causes foodborne gastroenteritis. Its biofilm-forming ability is known to be important for its survival in harsh conditions. Poultry is a main reservoir of Campylobacter. In this study, we evaluated the biofilm-forming ability, motility, and antibiotic susceptibility of Campylobacter strains isolated from commercially purchased chickens of various sources in South Korea. From 37 (30%) out of 124 chickens, a total of 78 Campylobacter isolates were obtained, and the ability of these strains to form biofilms was studied on polystyrene surfaces. We identified seven biofilm-forming strains of Campylobacter jejuni and Campylobacter coli, respectively, out of 60 C. jejuni and 18 C. coli strains. Our study demonstrated that motility is inconsistent with biofilm-forming ability, suggesting that motility is not a single factor affecting biofilm formation of Campylobacter. Moreover, there was no clear relationship between antibiotic resistance and biofilm-forming ability. DNase I treatment significantly inhibited the biofilm formation or degraded the mature biofilms of 3 C. coli and 1 C. jejuni biofilm-forming strains (p < 0.05). It suggests that extracellular DNA plays a significant role in the biofilm formation of these strains. Collectively, our study demonstrated that biofilm-forming ability is not strongly correlated with motility and antibiotic resistance in Campylobacter and that extracellular DNA is required for biofilm formation of the isolated Campylobacter strains. It also suggests that DNase I is a potential method for the control of Campylobacter biofilms.

Clonality, virulence and the occurrence of genes encoding antibiotic resistance among Staphylococcus warneri isolates from bloodstream infections.

Coagulase-negative Staphylococcuswarneri is an opportunistic pathogen capable of causing several infections, especially in patients with indwelling medical devices. We evaluated the virulence-associated properties of 23 clinical isolates recovered from blood specimens. In addition, the carriage of biofilm-associated genes, as well as antibiotic-resistant genes, was identified. S. warneri isolates appeared to be clonally unrelated and revealed a high degree of genetic diversity. All isolates revealed adhesion to epithelial cells, and 43.5 % of strains invaded the cells. Moreover, 52 % of isolates formed biofilm in vitro. PCR analysis demonstrated the presence of the ica operon, in two of the 12 biofilm-positive isolates. This indicated that biofilm formation, in this species, is not restricted to strains harbouring icaADBC genes, encoding polysaccharide intercellular adhesion. Analysis by confocal laser scanning microscopy revealed that biofilm-forming strains formed a three-dimensional structure, composed of mainly living cells. All strains revealed cell-contact cytotoxicity that was strongly associated with biofilm formation. Moreover, cell-free supernatants, of 95 % of the isolates, expressed a cytotoxic activity which caused the destruction of HeLa cells. S. warneri capable of forming biofilm carried significantly more genes encoding resistance to beta-lactams, aminoglicosides and macrolide-lincosamide streptogramin B antibiotics than biofilm-negative isolates. We have shown that tigecycline/rifampicin is effective against bacteria growing as a biofilm. The biofilm inhibitory concentration range of tigecycline/rifampicin was ≤1 µg ml-1. Results indicated that S. warneri have the ability to adhere, form biofilm, invade and destroy epithelial cells, which could be important mechanisms contributing to the development of diseases.

Inhibitory Effects of Plant Extracts on Pseudomonas aeruginosa Biofilm Formation

Background: Pseudomonas aeruginosa is opportunistic bacteria that cause diseases in human beings, animals and plants. It is one of the most important factors of the nosocomial infections in a wide range of patients with immunodeficiency including patients with malignant diseases, cystic fibrosis and burns. Biofilm production is one of the pathogenic factors of these bacteria. Objectives: The current study aimed to investigate the effects of a few plant extracts on in-vitro formation of Pseudomonas aeruginosa biofilm. Materials and Methods: Using the rotary system, the extracts of various plants were concentrated and prepared. Standard bacterial strains were provided and growth and biofilm formation of strains were determined using the microtiter plate method. Results: Results showed desirable antimicrobial effects of the silver nanoparticles and plant extract on the formation of the Pseudomonas aeruginosa biofilm and the highest effect was observed in silver nanoparticles and the lowest inhibitory effects were observed in Bucks beard and Prangos ferulaceae. Conclusions: Medicinal plants used in the study decreased the rate of biofilm formation. Since the biofilm formation is one of the pathogenic factors in mucoid strains, further studies will probably help to control the infections using the findings of the current study.

Biofilms of vaginal Lactobacillus reuteri CRL 1324 and Lactobacillus rhamnosus CRL 1332: kinetics of formation and matrix characterization.

Adhesion and biofilm formation are strain properties that reportedly contribute to the permanence of lactobacilli in the human vagina. The kinetics of biofilm formation and the chemical nature of the biofilm matrix formed by Lactobacillus reuteri CRL (Centro de Referencia para Lactobacilos Culture Collection) 1324 and Lactobacillus rhamnosus CRL 1332, vaginal beneficial strains, were evaluated in this work. Crystal violet-stained microplate assay and techniques of epifluorescence, electron and confocal microscopy were applied. The highest density and complexity of biofilms of both vaginal lactobacilli were observed at 72h of incubation. Protease, proteinase K, α-chymotrypsin and trypsin treatments efficiently detached L. reuteri CRL 1324 biofilm that was also partially affected by α-amylase. However, L. rhamnosus CRL 1332 biofilm was slightly affected by protease, proteinase K and α-amylase. Confocal microscopy revealed greater amount of polysaccharides in L. rhamnosus CRL 1332 biofilm matrix than in L. reuteri CRL 1324 biofilm matrix. The results indicate that proteins are one of the main components of the L. reuteri CRL 1324 biofilm, while the biofilm matrix of L. rhamnosus CRL 1332 is composed of carbohydrates and proteins. The results obtained support the knowledge, understanding and characterization of two biofilm-forming vaginal Lactobacillus strains.

Subtyping ofSalmonella entericaSubspecies I Using Single-Nucleotide Polymorphisms in Adenylate Cyclase

Methods to rapidly identify serotypes of Salmonella enterica subspecies I are of vital importance for protecting the safety of food. To supplement the serotyping method dkgB-linked intergenic sequence ribotyping (ISR), single-nucleotide polymorphisms were characterized within adenylate cyclase (cyaA). The National Center for Biotechnology Information (NCBI) database had 378 cyaA sequences from S. enterica subspecies I, which included 42 unique DNA sequences and 19 different amino acid sequences. Five representative isolates, namely serotypes Typhimurium, Kentucky, Enteritidis phage type PT4, and two variants of Enteritidis phage type PT13a, were differentiated within a microsphere-based fluidics system in cyaA by allele-specific primer extension. Validation against 25 poultry-related environmental Salmonella isolates representing 11 serotypes yielded a ∼89% success rate at identifying the serotype of the isolate, and a different region could be targeted to achieve 100%. When coupled with ISR, all serotypes were differentiated. Phage lineages of serotype Enteritidis 13a and 4 were identified, and a biofilm-forming strain of PT13a was differentiated from a smooth phenotype within phage type. Comparative ranking of mutation indices to genes such as the tRNA transferases, the diguanylate cyclases, and genes used for multilocus sequence typing indicated that cyaA is an appropriate gene for assessing epidemiological trends of Salmonella because of its relative stability in nucleotide composition.

Characterization and anti-biofilm activity of extracellular polymeric substances produced by the marine biofilm-forming bacterium Pseudoalteromonas ulvae strain TC14

This study investigated soluble (Sol-EPS), loosely bound (LB-EPS), and tightly bound extracellular polymeric substances (TB-EPS) harvested from biofilm and planktonic cultures of the marine bacterium Pseudoalteromonas ulvae TC14. The aim of the characterization (colorimetric methods, FTIR, GC-MS, NMR, HPGPC, and AFM analyses) was to identify new anti-biofilm compounds; activity was assessed using the BioFilm Ring Test®. A step-wise separation of EPS was designed, based on differences in water-solubility and acidity. An acidic fraction was isolated from TB-EPS, which strongly inhibited biofilm formation by marine bacterial strains in a concentration-dependent manner. The main constituents of this fraction were characterized as two glucan-like polysaccharides. An active poly(glutamyl-glutamate) fraction was also recovered from TB-EPS. The distribution of these key EPS components in Sol-EPS, LB-EPS, and TB-EPS was distinct and differed quantitatively in biofilm vs planktonic cultures. The anti-biofilm potential of the fractions emphasizes the putative antifouling role of EPS in the environment.

Functional analysis of stress protein data in a flor yeast subjected to a biofilm forming condition.

In this data article, an OFFGEL fractionator coupled to LTQ Orbitrap XL MS equipment and a SGD filtering were used to detect in a biofilm-forming flor yeast strain, the maximum possible number of stress proteins under the first stage of a biofilm formation conditions (BFC) and under an initial stage of fermentation used as reference, so-called non-biofilm formation condition (NBFC). Protein functional analysis – based on cellular components and biological process GO terms – was performed for these proteins through the SGD Gene Ontology Slim Mapper tool. A detailed analysis and interpretation of the data can be found in “Stress responsive proteins of a flor yeast strain during the early stages of biofilm formation” [1].

Comparison of telavancin and vancomycin lock solutions in eradication of biofilm-producing staphylococci and enterococci from central venous catheters

Results of a study of the activity of antibiotic lock solutions of vancomycin and telavancin against biofilm-forming strains of Staphylococcus epidermidis, Enterococcus faecalis, and Staphylococcus aureus are reported. An established in vitro central venous catheter model was used to evaluate lock solutions containing vancomycin (5 mg/mL) or telavancin (5 mg/mL), with and without preservative-containing heparin sodium (with 0.45% benzyl alcohol) 2500 units/mL, heparin, and 0.9% sodium chloride solution. Lock solutions were introduced after 24-hour bacterial growth in catheters incubated at 35 °C. After 72 hours of exposure to the lock solutions, catheters were drained, flushed, and cut into segments for quantification of colony-forming units. Against S. epidermidis, vancomycin and telavancin (with or without heparin) had similar activity. Against E. faecalis, vancomycin alone was more active than telavancin alone (p < 0.01). Against S. aureus, vancomycin plus heparin had activity similar to that of vancomycin alone; both lock agents had greater activity than telavancin (p < 0.02). The addition of heparin was associated with reduced activity of the vancomycin lock solution against S. epidermidis and E. faecalis (p < 0.01). Telavancin activity was not significantly changed with the addition of heparin. In a central venous catheter model, vancomycin and telavancin activity was similar in reducing biofilm-producing S. epidermidis. However, vancomycin was more active than telavancin against E. faecalis and S. aureus. None of the tested agents eradicated biofilm-forming strains. The addition of preservative-containing heparin sodium 2500 units/mL to vancomycin was associated with reduced activity against S. epidermidis and E. faecalis.

Inhibitory effects of antibiofilm compound 1 against Staphylococcus aureus biofilms.

A novel benzimidazole molecule that was identified in a small-molecule screen and is known as antibiofilm compound 1 (ABC-1) has been found to prevent bacterial biofilm formation by multiple bacterial pathogens, including Staphylococcus aureus, without affecting bacterial growth. Here, the biofilm inhibiting ability of 156 μM ABC-1 was tested in various biofilm-forming strains of S. aureus. It was demonstrated that ABC-1 inhibits biofilm formation by these strains at micromolar concentrations regardless of the strains' dependence on Polysaccharide Intercellular Adhesin (PIA), cell wall-associated protein dependent or cell wall- associated extracellular DNA (eDNA). Of note, ABC-1 treatment primarily inhibited Protein A (SpA) expression in all strains tested. spa gene disruption showed decreased biofilm formation; however, the mutants still produced more biofilm than ABC-1 treated strains, implying that ABC-1 affects not only SpA but also other factors. Indeed, ABC-1 also attenuated the accumulation of PIA and eDNA on cell surface. Our results suggest that ABC-1 has pleotropic effects on several biofilm components and thus inhibits biofilm formation by S. aureus.