Molecular epidemiology of ceftazidime-resistant Pseudomonas aeruginosa in Korea

Abstract

Pseudomonas aeruginosa is an important nosocomial pathogen with the potential to develop resistance to multiple antibiotics, particularly β-lactams. This study intends to define the prevalence and molecular epidemiology of the extended-spectrum β-lactamases (ESBLs), metallo-β-lactamases (MBLs), and extended-spectrum oxacillinases (ES-OXAs) that may confer β-lactam resistance to clinical P. aeruginosa isolates in Korea.From July to October 2008, 776 isolates of P. aeruginosa were collected from 17 Korean hospitals. ESBL, MBL, and ES-OXA genes were detected using PCR and subsequent sequencing. Pulsed field gel electrophoresis and multilocus sequence typing were used for genotyping. In 229 ceftazidime-resistant P. aeruginosa isolates, β-lactamases of Ambler classes A, B, and D were detected in 5 (2.2 %), 78 (34.1 %) and 80 (34.9 %) isolates, respectively. OXA-10 and IMP-6 were the most frequently produced β-lactamases in these isolates. Although ESBL prevalence is relatively low in P. aeruginosa isolates of Korea, the numbers of ES-OXA- and MBL-producers are high in comparison. The alarming prospect of increased MBLs in P. aeruginosa is further complicated by the ES-OXA production, which may remain undetected by routine phenotypic detection methods.