Phylogenetic group B2 expressed significant biofilm formation among drug-resistant uropathogenic Escherichia coli

Biofilm is an important virulent marker attributed to the development of urinary tract infections (UTIs) by uropathogenic E. coli (UPEC). Drug-resistant and biofilm-producing UPEC are highly problematic causing catheter-associated or recurrent UTIs with significant morbidity and mortality. The aim of the current study was to investigate the prevalence of biofilm formation and phylogenetic groups in drug-resistant UPEC to predict their ability to cause disease. This prospective study was conducted at the Department of Microbiology, University of Karachi from January to June 2019. A total of 50 highly drug-resistant UPEC were selected for this study. UPEC isolates were screened to form biofilm by Congo-red agar (CRA) and microtiter plate (MTP) technique. The representative biofilm-producing isolates were analysed by scanning electron microscopy (SEM) monitoring. Phylogenetic analysis was done by PCR method based on two preserved genes; chuA, yjaA and TspE4-C2 DNA fragment. On CRA 34 (68%) UPEC were slime producers, while on MTP 20 (40%) were strong biofilm producers, 19 (38%) moderate and 11 (22%) were low to negligible biofilm producers. Molecular typing confirmed that phylogenetic group B2 was prevalent in drug resistant UPEC strains. Pathogenic strains belonged to phylogenetic group B2 and D were found to have greater biofilm forming ability as compare to non-pathogenic commensal strains that belonged to phylogenetic group A. Our results indicate that biofilm formation vary in drug resistant UPEC belonged to different phylogenetic groups. This study indicates possible link between in vitro biofilm formation and phylogenetic groups of UPEC, therefore this knowledge might be helpful to predict the pathogenic potential of UPEC and help design strategies for controlling UTIs

The Impact of UV Radiation on Biofilms of Multi-Drug Resistant Nosocomial Bacteria

AIM & BACKGROUND: Germicidal ultraviolet radiation is widely used in healthcare settings for broad-spectrum sterilization. UV radiation damages microbial DNA by inducing pyrimidine dimerization. However, a comprehensive assessment of UV sterilization efficacy against nosocomial bacterial strains known for biofilm formation remains unexplored. This study aims to evaluate the sterilization effectiveness of UV irradiation on prevalent healthcare-associated pathogens with biofilm-forming potential. METHODOLOGY: Common pathogens, including Staphylococcus aureus, Methicillin-resistant S. aureus, Escherichia coli, and Pseudomonas aeruginosa, were cultivated on their specified bacteriological media. Selected strains were reconfirmed using 16s PCR. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method and CLSI guidelines. Biofilm potential was assessed using a 96-well titer plate method. The titer plates were exposed to a UV germicidal emitter (254nm) at a distance of 50 cm inside a biological safety cabinet. Germicidal activity was evaluated using viability tests, crystal violet assays, scanning electron microscopy, and reconfirmed by atomic force microscopy, the results of exposed and non-exposed biomasses were compared statistically. RESULTS: S. aureus and MRSA were eradicated within 5 minutes of UV exposure, while P. Aeruginosa and E. Coli required 15 to 20 minutes for complete eradication. However, there was no significant difference in the biomass and ultrastructure of UV-exposed microbial biofilms compared to controls. This study demonstrates that UV disinfection is effective against biofilm-producing, multi-drug resistant pathogens. However, it does not affect the biofilm and extracellular polymeric substances of all pathogens. The biofilm of P. Aeruginosa was found to be the most resilient

Isolation and identification of Biofilm-producing E. coli from drinking water.

Background: The increasing rate of water-borne diseases in Karachi demands the characterization of associated pathogens. Nowadays, water-borne infections become more resistant to treatment due to biofilm formation and excessive use of antibiotics. Biofilm formation in water deteriorates the quality of water. This study identified and characterized biofilm-producing E. coli in drinking water. Methodology: Water samples were analyzed for heterotrophic plate count and total coliforms, fecal coliforms, and E. coli. The Kirby disk bar diffusion method was used to investigate antibiotic susceptibility in biofilm-producing E. coli. The Congo red and tube ring methods were used to identify biofilm producers. The effect of biofilm formation on the hydrophobicity of E. coli was performed by the BATH method. The soft agar method determines the colony spreading ability of biofilm and non-biofilm producers. Molecular characterization of virulence genes of E. coli was performed by a PCR. Scanning electron microscopy for biofilm construction was conducted.   Results: The total 120 water samples were tested for heterotrophic plate count and total coliforms, fecal coliforms, and E. coli. 78% were unfit in this study, and 21.66% were fit. 38 E. coli strains were found in water samples. According to findings, the hydrophobicity of biofilm-producing isolates increased with the incubation period. Colony-forming unit drops one logarithm in the biofilm state compared to the planktonic stage. Biofilm producers were more resistant to antibiotics. The virulence genes, pet, lt, and stx2, were used for the molecular characterization. Conclusion: The presence of biofilm-producing E. coli in drinking water is alarming, and it indicates inappropriate treatment of the water supply system. To prevent rapid water-borne diseases, adequate actions are required to control drinking-water biofilm producers.</jats:p