Characterization of Virulence Hallmarks of Pseudomonas Strains Isolated from Urinary Tract Infections

Abstract

Urinary tract infections (UTIs) are the most prevalent bacterial infections, affecting 150 million people worldwide every year. Pseudomonas is one of the most common uropathogen, posing a risk to both community and hospital settings due to its ability to thrive in the host environment by secreting various virulence factors that help in causing infections. In the present study, the virulence hallmarks of Pseudomonas strains associated with urinary tract infections were determined. Total 50 isolated and purified bacteria were revived from glycerol stocks, and their identification was confirmed as Pseudomonas aeruginosa through a sequence of biochemical tests including oxidase, catalase, triple sugar iron test, sulphide indole motility test, citrate utilization test, methyl red-Voges-Proskauer test, and nitrate reduction test. Bacterial Phenotypic detection of virulence factors in Pseudomonas isolates was identified by performing various assays. The biofilm-forming potential of P. aeruginosa was evaluated both by the Congo red assay and the microtiter plate assay. The motility traits were identified as swimming, swarming, and twitching. Additionally, these isolates were inoculated on egg yolk agar, skimmed milk agar, blood agar, Christensen urea agar, and cetrimide agar to assess their ability to produce extracellular virulence factors, i.e., phospholipase C, proteases, hemolysins, urease, and pigments, respectively. In the microtiter plate assay, 28% of isolates were non-biofilm formers, 46% exhibited weak biofilm formation, 16% showed moderate biofilm formation, and 10% demonstrated strong biofilm-forming ability. In contrast, the Congo red assay identified 86% of isolates as non-biofilm producers, while only 14% were biofilm formers. The three types of motility traits were assessed, and the majority of isolates showed swimming motility (95%), followed by twitching (82%) and swarming motility (62%), indicating their pathogenic potential. A large number of these isolates consistently displayed many extracellular virulence factors, 100% expressed phospholipase and urease production, 98% demonstrated hemolysin production, and 96% exhibited protease activity. Moreover, pigment production was determined by cetrimide agar, where pyoverdine pigment was found in all isolates, while pyocyanin pigment was observed in 82% of isolates. Among these isolates, all were highly pathogenic strains of P. aeruginosa with a large number of virulence factors. These strains were acquired in hospital settings and associated with urinary tract infections. There is a pressing need to develop target-based therapeutic strategies to combat Pseudomonas-associated urinary tract infections.