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KMID : 0981820090290030218
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Korean Journal of Laboratory Medicine
2009 Volume.29 No. 3 p.218 ~ p.223
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Prevalence of the Extended-Spectrum β-Lactamase and qnr Genes in Clinical Isolates of Escherichia coli
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Park Yong-Jung
Lee Kyung-Won
Kang Hyun-Kyung
Bae Il-Kwon
Kim Ju-Won
Kim Jae-Seok
Uh Young
Jeong Seok-Hoon
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Abstract
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Background: This study was performed to investigate the prevalence of qnr genes in clinical isolates of Escherichia coli from Korea that produce extended-spectrum β-lactamases (ESBLs).
Methods: During the period of May to June 2005, we collected clinical isolates of E. coli that were intermediate or resistant to ceftazidime and/or cefotaxime from 11 Korean hospitals. Antimicrobial susceptibility was determined by the disk diffusion and agar dilution methods. ESBL production was confirmed phenotypically by the double-disk synergy test. ESBL and qnr genes were searched for by PCR amplification, and the PCR products were then subjected to direct sequencing.
Results: Double-disk synergy tests were positive in 84.3% (118/140) of ceftazidime- and/or cefotaxime-nonsusceptible E. coli isolates. The most prevalent types of ESBL in E. coli isolates were CTXM- 14 (N=41) and CTX-M-15 (N=58). Other ESBLs were also identified, including CTX-M-3 (N=7),CTX-M-9 (N=8), CTX-M-12 (N=1), CTX-M-57 (N=1), SHV-2a (N=2), SHV-12 (N=17) and TEM-52 (N=4). The qnrA1 and qnrB4 genes were identified in 4 and 7 ESBL-producing isolates, respectively.
Conclusion: CTX-M-type enzymes were the most common type of ESBL in E. coli isolates from Korea, and the qnr genes were not uncommon in ESBL-producing E. coli isolates. Dissemination of E. coli containing both ESBL and qnr genes could compromise the future usefulness of the expanded-spectrum antibiotics for the treatment of infections.
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KEYWORD
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Escherichia coli, CTX-M ESBL, qnrA1, qnrB4
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