Environmental and Clinical Pseudomonas aeruginosa Isolates with Pooled Presence of exo S, exo U, exo T and exo Y genes

Pseudomonas aeruginosa is one of the important opportunistic pathogens causing life threatening nosocomial infections. Both clinical and environmental isolates can be considered potential pathogens due to the conservation of some of the virulence genes. Present study aimed at evaluating the prevalence and diversity of some of the virulence genes among P. aeruginosa isolates from clinical and environmental samples. In this study, 70 clinical (sputum and swab) and 31 environmental isolates were checked for the presence of 8 different virulence genes by PCR amplification. Genetic diversity was studied by performing Enterobacterial repetitive intergenic consensus (ERIC) PCR followed by cluster analysis using GelCompar II software. There was a significant difference in the number of clinical and environmental isolates possessing virulence genes (t = 8.2, c2 = 28.257 at p ≤ 0.05). 10 clinical and 1 environmental isolate was found to possess all four genes of the type III secretion system (exoS, exoU, exoT and exoY). Cluster analysis revealed 3 major groups with some of the environmental isolates clustering with the clinical ones. To the best of our knowledge, this is the first study to report the presence of all four genes involved in type III secretion system in P. aeruginosa. Presence of several virulence traits in the environmental isolates suggests the possibility of these non clinical ones becoming a clinical pathogenic one. The similarity of three environmental isolates with the clinical ones shows the likelihood of infection caused by them in a hospital setting

Comparison of Antibiofilm Activity of <i>Pseudomonas aeruginosa</i> Phages on Isolates from Wounds of Diabetic and Non-Diabetic Patients

The persistence of organisms as biofilms and the increase in antimicrobial resistance has raised the need for alternative strategies. The study objective was to compare the ability of isolated bacteriophages to remove in vitro biofilms formed by Pseudomonas aeruginosa isolated from the environment with those isolated from diabetic and non-diabetic wounds. P. aeruginosa were isolated from clinical and environmental sites, and antimicrobial susceptibility was tested. Bacteriophages were isolated and characterized based on plaque morphology and host range. A reduction in the viable count assayed the lytic ability of candidate phages. The crystal violet method was used to determine the residual biofilm after 24 h of phage treatment on 72-h-old biofilms. The statistical significance of phage treatment was tested by one-way ANOVA. Of 35 clinical isolates, 17 showed resistance to 1 antibiotic at least, and 7 were multidrug resistant. Nineteen environmental isolates and 11 clinical isolates were drug-sensitive. Nine phages showed 91.2% host coverage, including multidrug-resistant isolates. Phages eradicated 85% of biofilms formed by environmental isolates compared to 58% of biofilms of diabetic isolates and 56% of biofilms of non-diabetic isolates. Clinical isolates are susceptible to phage infection in planktonic form. Biofilms of P. aeruginosa isolated from diabetic wounds and non-diabetic wounds resist removal by phages compared to biofilms formed by environmental isolates. All phages were efficient in dispersing PAO1 biofilms. However, there was a significant difference in their ability to disperse PAO1 biofilms across the different surfaces tested. Partial eradication of biofilm by phages can aid in complementing antibiotics that are unable to penetrate biofilms in a clinical set-up