Escherichia coli Korean Source extended-spectrum β-lactamase Korean Source qnr Korean Source

Translated title of the contribution: Prevalence of the extended-spectrum β-lactamase and qnr genes in clinical isolates of Escherichia coli

Yongjung Park, Hyun Kyung Kang, Il Kwon Bae, Juwon Kim, Jae Seok Kim, Young Uh, Seokhoon Jeong, Kyungwon Lee

Research output: Contribution to journalArticle

18 Citations (Scopus)


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. Conclusions: 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.

Original languageKorean
Pages (from-to)218-223
Number of pages6
JournalKorean Journal of Laboratory Medicine
Issue number3
Publication statusPublished - 2009 Oct 12


All Science Journal Classification (ASJC) codes

  • Biochemistry, medical
  • Clinical Biochemistry

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