The presence of exotoxin genes and biofilm production in carbapenem-resistant Pseudomonas aeruginosa clinical isolates.

Abstract

Introduction: Pseudomonas aeruginosa produces many exotoxins which are essential for the bacterial pathogenesis. The aim of this study was to identify Pseudomonas aeruginosa from clinical specimens, detect the sensitivity pattern, biofilm production, and the frequency of exogenes.

Methods: Pseudomonas aeruginosa clinical isolates were identified by conventional and genotypic methods. Antibiotic susceptibility patterns and biofilm production were performed. Molecular detection of exotoxin genes exoS, exoT, exoU, and exoY in Pseudomonas aeruginosa isolates was performed by PCR.

Results: Seventy-five Pseudomonas aeruginosa were identified in 400 clinical specimens. Sixty-six (88%) isolates were carbapenem-resistant. A total of 25 (33.3%) isolates were extensively drug resistant, 18 (24%) were multidrug resistant, and 11 (14.7%) were pandrug resistant. Sixty-three (84%) isolates were biofilm producers. Biofilm formation was detected in 56 (85%) of carbapenem-resistant isolates. Totally, 70 (93.3%) isolates carried exoS, 68 (90.7%) carried exoY, 65 (86.7%) carried exoT, and 28 (37.3%) carried exoU. Exogenes were highly expressed in carbapenem-resistant isolates. Coexistence of more than one gene was detected in nearly all isolates.

Conclusions: Pseudomonas aeruginosa clinical isolates were resistant to many anti-pseudomonal antibiotics. Most of isolates were biofilm-producers. The genes exoT, exoS and exoY were identified in almost all P. aeruginosa strains and are considered an inevitable component of P. aeruginosa virulence.