Determination of PER-1 and OXA-10-like beta-lactamases in Ceftazidime-Resistant Pseudomonas aeruginosa Isolates by Molecular Methods

Abstract

Objective: Pseudomonas aeruginosa is one of the important nosocomial pathogens and resistant to many antibiotics including beta-lactams. PER-1 and OXA-10 type extended-spectrum beta-lactamases (ESBLs), the major beta-lactamases, were identified in P. aeruginosa. The aim of this study was to identify PER-1 (blaPER-1) and OXA-10 (blaOXA-10)-like beta-lactamases in ceftazidime- resistant nosocomial P. aeruginosa strains. Material and Methods: The presence of PER-1 and OXA-10 like beta-lactamases was investigated by polymerase chain reaction in 50 ceftazidime-resistant P. aeruginosa strains isolated from patients hospitalized in various clinics of Ondokuz Mayis University, School of Medicine between 2007 and 2008. The PER and OXA-10-like beta-lactamases were analyzed by restriction fragment length polymorphism (RFLP) and followed by pulsed-field gel electrophoresis (PFGE) for the determination of clonal relationship of the strains. Results: The blaPER-1 gene and blaOXA-10 like gene were detected in 23 (46%) and 39 (78%) of the 50 of ceftazidime-resistant P. aeruginosa isolates, respectively. In addition, both of the two beta-lactamase genes were also detected in 12 (23%) of the isolates. PER-1 and OXA-10, -11, -14, -16 types were identified by RFLP analysis. Although the PFGE typing results yielded 11 different banding patterns, 74% (n=37) of the all P. aeruginosa strains were included in four main patterns. Conclusion: It was concluded that the prevalence of PER-1 and OXA-10 enzymes was common among ceftazidime resistant P. aeruginosa isolates. PER-1 and OXA-10 enzymes produced the isolates were being transmitted horizontally as the most of the isolates were clonally related.