Prevalence of Ambler class A and D β-lactamases among clinical isolates of Pseudomonas aeruginosa in Korea (original) (raw)

2005, Journal of Antimicrobial Chemotherapy

Objectives: Recently, resistance to extended-spectrum cephalosporins due to acquired b-lactamases has been reported in Pseudomonas aeruginosa. The aim of this study was to investigate the prevalence of Ambler class A and D b-lactamases and their extended-spectrum derivatives and antimicrobial susceptibilities of P. aeruginosa isolated from various parts of Korea. Methods: A total of 252 consecutive, non-duplicate isolates of P. aeruginosa were studied for the presence of class A or D b-lactamase. Antibiotic susceptibility tests and PCR amplification of genes encoding class A (bla PSE-1 , bla PER-1 , bla VEB-1 , bla TEM , bla SHV , bla CTX-M and bla GES-1) and class D b-lactamases (bla OXA-groupI , bla OXA-groupII and bla OXA-groupIII) were performed. For PCR-positive isolates, isoelectric focusing (IEF) analysis, sequencing and pulsed-field gel electrophoresis (PFGE) were performed. Results: In 64 (25.4%) isolates, structural genes for PSE-1 (6.3%), OXA-10 (13.1%), OXA-4 (4.3%), OXA-30 (2.0%), OXA-2 (2.3%) and OXA-17 (0.4%) were found; their distribution varied between provinces. None harboured bla PER-1 , bla VEB-1 , bla TEM , bla SHV , bla CTX-M and bla GES-1. The cross-class resistance rates to other antibiotics was significantly higher in class A and D b-lactamase producers than in non-producers (P < 0.001 for aminoglycosides, ciprofloxacin and meropenem). Conclusions: OXA-type b-lactamases are widespread, but their extended-spectrum derivatives are rare among P. aeruginosa in Korea. To our knowledge, this is the first report of OXA-17, an extendedspectrum derivative of OXA-10, outside the Middle East. In addition, combined resistance to ticarcillin and aminoglycosides was a useful indicator for P. aeruginosa producing PSE-or OXA-type b-lactamases in this study.