Comparative study of virulence factors among ESβL-producing and nonproducing Pseudomonas aeruginosa clinical isolates.

BACKGROUND/AIM β-Lactamase production is considered one of the most important resistance mechanisms amongvirulent Pseudomonas aeruginosa isolates. The aim of this study was to compare the production and antimicrobial resistance patterns of some virulence factors in extended spectrum β-lactamase (ESβL)-producing and nonproducing P. aeruginosa clinical isolates. MATERIALS AND METHODS Out of 183 different clinical specimens, 104 Pseudomonas aeruginosa isolates were recovered. The isolates were screened for ESβL production using the double disk diffusion test and phenotypic confirmatory disk diffusion test. All isolates were tested for susceptibility to 25 antimicrobials, as well as for expression of various virulence factors including pigment, hemolysin, gelatinase, protease, lipase, rhamnolipids, biofilm, and cell surface hydrophobicity. The results of ESβL producers and honproducers were statistically compared. RESULTS All isolates showed a high frequency of multiple resistance to at least 14 and up to 25 of the tested antimicrobials. Nevertheless, most virulence factors were produced at higher rates in ESβL-producing than in ESβL-nonproducing Pseudomonas aeruginosa isolates. CONCLUSION The results of this study suggest a correlation between ESβL phenotype and the production of some factors that are reported to be involved in the virulence of P. aeruginosa.