Correlation between antibiotic resistance and virulence of Pseudomonas aeruginosa clinical isolates.

BACKGROUND/AIM: Virulent Pseudomonas aeruginosa. is frequently life-threatening and often challenging to treat, and the emergence of multidrug-resistant isolates presents a critical problem for patients. The aim of the study was concerned with molecular analysis of the virulence factors and antimicrobial resistance profile of multidrug-resistant P. aeruginosa (MDRPA). MATERIALS AND METHODS: Out of 44 MDRPA isolates, 12 isolates representing different resistance profiles and sources of samples were selected for further molecular studies. Polymerase chain reaction (PCR) approaches were applied to identify the genes implicated in antimicrobial resistance or virulence factors in the selected MDRPA isolates. RESULTS: Multidrug-resistance (pstS), ß-lactamase (IMP7, IMP10, IMP13, and IMP25), and extended spectrum ß-lactamase (blaOXA50) genes were detected in all of the selected MDRPA isolates. However, only 4 (33%) MDRPA isolates were positive for the presence of the extended spectrum ß-lactamase (blaOXA2) gene. Furthermore, the hemolytic phospholipase C precursor gene (plcH) was detected in all PCR products of the tested MDRPA isolates while the exotoxin A (toxA) gene was absent. Other virulence genes were detected with variable percentage in tested isolates. CONCLUSION: The statistical analysis revealed a significantly positive correlation (r = 0.779, P = 0.002) between virulence factors and antimicrobial resistance marker profiles of the tested MDRPA isolates.

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

BACKGROUND/AIM: ß-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 ß-lactamase (ESßL)-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 ESßL 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 ESßL 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 ESßL-producing than in ESßL-nonproducing Pseudomonas aeruginosa isolates. CONCLUSION: The results of this study suggest a correlation between ESßL phenotype and the production of some factors that are reported to be involved in the virulence of P. aeruginosa.