Disperse red 15 (DR15) impedes biofilm formation of uropathogenic Escherichia coli.

Catheter associated urinary tract infection (CAUTI) is a highly prevalent hospital-acquired infection that is predominantly caused by uropathogenic Escherichia coli (UPEC). It adheres on catheter surface using type I pili as the initial step of pathogenesis that progresses to form biofilm. In this study, potential inhibitors against FimH adhesin of type I pili were screened computationally that yielded ten compounds. These were further validated in vitro against adhesion and biofilm formation. The compounds, 1-Amino-4-hydroxyanthraquinone (Disperse Red 15 or DR15) and 4-(4'-chloro-4-biphenylylsulfonylamino) benzoic acid (CB1) impaired adhesion and biofilm formation without inhibiting the planktonic growth. Also, both compounds inhibited cell assemblages like autoaggregation and swarming motility by unknown mechanisms. DR15 was further derivatised into N-(4-hydroxy-9,10-dioxo-9,10-dihydroanthracen-1-yl) undec-10-enamide that self-assembled with linseed oil, which was used as the coating material on urinary Foley catheters. The thin-film coating on the catheter did not leach when incubated in artificial urine and effectively restricted biofilm formation of UPEC. Altogether, the thin-film coating of urinary catheter with DR15 inhibited biofilm formation of UPEC and this application could potentially help to reduce CAUTI incidents in healthcare facilities.

Nitrate levels modulate the abundance of Paracoccus sp. in a biofilm community.

Conditions required to enhance a particular species efficient in degradative capabilities is very useful in wastewater treatment processes. Paracoccus sp. is known to efficiently reduce nitrogen oxides (NOx) due to the branched denitrification pathway. Individual-based simulations showed that the relative fitness of Paracoccus sp. to Pseudomonas sp. increased significantly with nitrate levels above 5 mM. Spatial structure of the biofilm showed substantially less nitrite levels in the areas of Paracoccus sp. dominance. The simulation was validated in a laboratory reactor harboring biofilm community by fluorescent in situ hybridization, which showed that increasing nitrate levels enhanced the abundance of Paracoccus sp. Different levels of NOx did not display any significant effect on biofilm formation of Paracoccus sp., unlike several other bacteria. This study shows that the attribute of Paracoccus sp. to tolerate and efficiently reduce NOx is conferring a fitness payoff to the organism at high concentrations of nitrate in a multispecies biofilm community.

Biogenic amine tryptamine in human vaginal probiotic isolates mediates matrix inhibition and thwarts uropathogenic E. coli biofilm.

Probiotics offer a promising prophylactic approach against various pathogens and represent an alternative strategy to combat biofilm-related infections. In this study, we isolated vaginal commensal microbiota from 54 healthy Indian women to investigate their probiotic traits. We primarily explored the ability of cell-free supernatant (CFS) from Lactobacilli to prevent Uropathogenic Escherichia coli (UPEC) colonization and biofilm formation. Our findings revealed that CFS effectively reduced UPEC's swimming and swarming motility, decreased cell surface hydrophobicity, and hindered matrix production by downregulating specific genes (fimA, fimH, papG, and csgA). Subsequent GC-MS analysis identified Tryptamine, a monoamine compound, as the potent bioactive substance from Lactobacilli CFS, inhibiting UPEC biofilms with an MBIC of 4 µg/ml and an MBEC of 8 µg/ml. Tryptamine induced significant changes in E. coli colony biofilm morphology, transitioning from the Red, Dry, and Rough (RDAR) to the Smooth and White phenotype, indicating reduced extracellular matrix production. Biofilm time-kill assays demonstrated a four-log reduction in UPEC viability when treated with Tryptamine, highlighting its potent antibacterial properties, comparable to CFS treatment. Biofilm ROS assays indicated a significant elevation in ROS generation within UPEC biofilms, suggesting a potential antibacterial mechanism. Gene expression studies with Tryptamine-treated samples showed a reduction in expression of curli gene (csgA), consistent with CFS treatment. This study underscores the potential of Tryptamine from probiotic Lactobacilli CFS as a promising antibiofilm agent against UPEC biofilms.

Nutrients determine the spatial architecture of Paracoccus sp. biofilm.

Bacterial biofilms adapt and shape their structure in response to varied environmental conditions. A statistical methodology was adopted in this study to empirically investigate the influence of nutrients on biofilm structural parameters deduced from confocal scanning laser microscope images of Paracoccus sp.W1b, a denitrifying bacterium. High concentrations of succinate, Mg(++), Ca(++), and Mn(++) were shown to enhance biofilm formation whereas higher concentration of iron decreased biofilm formation. Biofilm formed at high succinate was uneven with high surface to biovolume ratio. Higher Mg(++) or Ca(++) concentrations induced cohesion of biofilm cells, but contrasting biofilm architectures were detected. Biofilm with subpopulation of pillar-like protruding cells was distributed on a mosaic form of monolayer cells in medium with 10 mM Mg(++). 10 mM Ca(++) induced a dense confluent biofilm. Denitrification activity was significantly increased in the Mg(++)- and Ca(++)-induced biofilms. Chelator treatment of various biofilm ages indicated that divalent cations are important in the initial stages of biofilm formation.

Matrix inhibition by Salmonella excludes uropathogenic E. coli from biofilm.

Biofilm is a predominant lifestyle of bacteria that comprises of cells as collectives enmeshed in a polymeric matrix. Biofilm formation is vital for bacterial species as it provides access to nutrients and protects the cells from environmental stresses. Here we show that interference in biofilm matrix production is a strategy by the competing bacterial species to reduce the ability of the other species to colonize a surface. Escherichia coli colonies that differ in matrix production display different morphologies on Congo red agar media, which we exploited for screening bacterial isolates capable of inhibiting the matrix. The cell-free supernatants from growth culture of the screened isolates impaired uropathogenic E. coli (UPEC) UTI89 strain's biofilm. A physicochemical analysis suggested that the compound could be a glycopeptide or a polysaccharide. Isolates that inhibited matrix production belonged to species of the family Enterobacteriaceae such as Shigella, Escherichia, Enterobacter and Salmonella. Competition experiments between the isolates and the UPEC strain resulted in mutual inhibition, particularly during biofilm formation causing significant reduction in productivity and fitness. Furthermore, we show that Salmonella strains competitively excluded the UPEC strain in the biofilm by inhibiting its matrix production, highlighting the role of interference competition.

An injectable self-healing anesthetic glycolipid-based oleogel with antibiofilm and diabetic wound skin repair properties.

Globally, wound infections are considered as one of the major healthcare problems owing to the delayed healing process in diabetic patients and microbial contamination. Thus, the development of advanced materials for wound skin repair is of great research interest. Even though several biomaterials were identified as wound healing agents, gel-based scaffolds derived from either polymer or small molecules have displayed promising wound closure mechanism. Herein, for the first time, we report an injectable and self-healing self-assembled anesthetic oleogel derived from glycolipid, which exhibits antibiofilm and wound closure performance in diabetic rat. Glycolipid derived by the reaction of hydrophobic vinyl ester with α-chloralose in the presence of novozyme 435 undergoes spontaneous self-assembly in paraffin oil furnished an oleogel displaying self-healing behavior. In addition, we have prepared composite gel by encapsulating curcumin in the 3D fibrous network of oleogel. More interestingly, glycolipid in its native form demoed potential in disassembling methicillin-resistant Staphylococcus aureus, methicillin-susceptible Staphylococcus aureus, and Pseudomonas aeruginosa biofilms. Both oleogel and composite gel enhanced the wound skin repair in diabetic induced Wistar rats by promoting collagen synthesis, controlling free radical generation and further regulating tissue remodeling phases. Altogether, the reported supramolecular self-assembled anesthetic glycolipid could be potentially used for diabetic skin wound repair and to treat bacterial biofilm related infections.

Corrigendum: Successful treatment of biofilm infections using shock waves combined with antibiotic therapy.

This corrects the article DOI: 10.1038/srep17440.

An Electronic Nose for Royal Delicious Apple Quality Assessment - A Tri-layer Approach.

Foodborne pathogens cause serious health issues and have a strong impact on the economy of the country. In this context, quality testing of royal delicious apple by detecting pathogen contamination using an electronic nose, which contains an array of six ready-made sensors, has been proposed. To estimate the types of pathogens, fresh, half and completely contaminated apple samples were considered for bacterial studies. This study revealed the presence of Staphylococcus, Salmonella and Shigella bacteria, which were in the order of zero, 102, 103-104 CFU/mL. Further, the recorded headspace GC-MS spectra of contaminated samples confirmed the presence of bacterial spoilage markers namely acetone, ethyl acetate, ethyl alcohol and acetaldehyde. Voltage swing of 0.2 and 0.5 V was observed for half and completely contaminated apple samples respectively with reference to the fresh sample. Voltage responses of the sensors fed to Principal component analysis and Ward's method of hierarchical cluster algorithms helped to assess the quality of apple samples. By correlating the results of tri-layers namely bacterial count, GCMS data and classification results, reference table was developed and embedded in the ATmega processor of the electronic nose for real-time quality estimation of apple samples.

Disassembly of Bacterial Biofilms by the Self-Assembled Glycolipids Derived from Renewable Resources.

More than 80% of chronic infections of bacteria are caused by biofilms. It is also a long-term survival strategy of the pathogens in a nonhost environment. Several amphiphilic molecules have been used in the past to potentially disrupt biofilms; however, the involvement of multistep synthesis, complicated purification and poor yield still remains a major problem. Herein, we report a facile synthesis of glycolipid based surfactant from renewable feedstocks in good yield. The nature of carbohydrate unit present in glycolipid influence the ring chain tautomerism, which resulted in the existence of either cyclic structure or both cyclic and acyclic structures. Interestingly, these glycolipids self-assemble into gel in highly hydrophobic solvents and vegetable oils, and displayed foam formation in water. The potential application of these self-assembled glycolipids to disrupt preformed biofilm was examined against various pathogens. It was observed that glycolipid 6a disrupts Staphylococcus aureus and Listeria monocytogenes biofilm, while the compound 6c was effective in disassembling uropathogenic E. coli and Salmonella enterica Typhimurium biofilms. Altogether, the supramolecular self-assembled materials, either as gel or as surfactant solution could be potentially used for surface cleansing in hospital environments or the food processing industries to effectively reduce pathogenic biofilms.

Successful treatment of biofilm infections using shock waves combined with antibiotic therapy.

Many bacteria secrete a highly hydrated framework of extracellular polymer matrix on suitable substrates and embed within the matrix to form a biofilm. Bacterial biofilms are observed on many medical devices, endocarditis, periodontitis and lung infections in cystic fibrosis patients. Bacteria in biofilm are protected from antibiotics and >1,000 times of the minimum inhibitory concentration may be required to treat biofilm infections. Here, we demonstrated that shock waves could be used to remove Salmonella, Pseudomonas and Staphylococcus biofilms in urinary catheters. The studies were extended to a Pseudomonas chronic pneumonia lung infection and Staphylococcus skin suture infection model in mice. The biofilm infections in mice, treated with shock waves became susceptible to antibiotics, unlike untreated biofilms. Mice exposed to shock waves responded to ciprofloxacin treatment, while ciprofloxacin alone was ineffective in treating the infection. These results demonstrate for the first time that, shock waves, combined with antibiotic treatment can be used to treat biofilm infection on medical devices as well as in situ infections.

Carbon sources influence the nitrate removal activity, community structure and biofilm architecture.

Influence of the frequently used carbon sources in nitrate removal processes were evaluated in a lab-scale biofilm reactor. The NO3-N removal efficiency was in the order acetate>glucose>methanol>ethanol. Acetate-fed biofilm reduced nearly 100% NO3-N with negligible amount of NO2-N accumulation. Although 99% NO3-N was reduced in the glucose-fed biofilm, substantial NH3-N and NO2-N accumulated. Methanol-fed biofilm reduced 72% of NO3-N with accumulation of 2.2 mg L(-1) of NO2-N, while biofilm formed in presence of ethanol showed 61% reduction in NO3-N although relatively higher ratio of denitrifiers were observed. Acetate and ethanol-fed biofilm displayed characteristic biofilm architecture with voids, but the former had relatively higher thickness and diffusion distance. In presence of glucose and methanol, a confluent biofilm without characteristic voids was formed. Pseudomonas sp. numerically dominated the acetate and ethanol-fed biofilm, while Enterobacter sp. and Methylobacillus sp., were abundant in glucose and methanol biofilms respectively.

Assessment of denitrifying bacterial composition in activated sludge.

The abundance and structure of denitrifying bacterial community in different activated sludge samples were assessed, where the abundance of denitrifying functional genes showed nirS in the range of 10(4)-10(5), nosZ with 10(4)-10(6) and 16S rRNA gene in the range 10(9)-10(10) copy number per ml of sludge. The culturable approach revealed Pseudomonas sp. and Alcaligenes sp. to be numerically high, whereas culture independent method showed betaproteobacteria to dominate the sludge samples. Comamonas sp. and Pseudomonas fluorescens isolates showed efficient denitrification, while Pseudomonas mendocina, Pseudomonas stutzeri and Brevundimonas diminuta accumulated nitrite during denitrification. Numerically dominant RFLP OTUs of the nosZ gene from the fertilizer factory sludge samples clustered with the known isolates of betaproteobacteria. The data also suggests the presence of different truncated denitrifiers with high numbers in sludge habitat.