JAC Advance Access originally published online on September 26, 2006
Journal of Antimicrobial Chemotherapy 2006 58(6):1257-1259; doi:10.1093/jac/dkl397
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Emergence of CTX-M-12 extended-spectrum ß-lactamase-producing Escherichia coli in Korea
1 Department of Laboratory Medicine, Kosin University College of Medicine 602-030, 34 Amnam-Dong, Suh-Gu, Busan, Korea 2 Department of Quality Improvement, Pusan National University Hospital 602-739, 1-10 Ami-Dong, Suh-Gu, Busan, Korea 3 Center for Food Safety Evaluation, Korea Food and Drug Administration 122-704, 231 Jinheung-Ro, Eunpyung-Gu, Seoul, Korea 4 Department of Laboratory Medicine, Hallym University College of Medicine 150-950, 948-1 Daerim 1-Dong, Yongdeungpo-Gu, Seoul, Korea 5 R&D Park, LG Life Sciences, Ltd 305-380, 104-1 Moonji-Dong, Yuseong-Gu, Daejeon, Korea
Received 31 May 2006; returned 5 July 2006; revised 25 August 2006; accepted 11 September 2006
*Corresponding author. Tel: +82-51-990-6373; Fax: +82-51-990-3034; E-mail: kscpjsh{at}ns.kosinmed.or.kr
Objectives: To characterize CTX-M-12 extended-spectrum ß-lactamase (ESBL) produced by clinical Escherichia coli isolates and to investigate its genetic environment.
Methods: Antimicrobial susceptibilities were determined by disc diffusion and agar dilution methods, and the double-disc synergy test was carried out. Detection of genes encoding class A ß-lactamases was performed by PCR amplification, and the genetic environments of the blaCTX-M-12 genes were investigated by PCR and sequencing of the regions surrounding the genes. Kinetic parameters were determined from purified CTX-M-12.
Results: Sequence data for the CTX-M-1 cluster from three clinical E. coli isolates indicated the presence of CTX-M-12. An ISEcp1 insertion sequence was located 49 bp upstream of blaCTX-M-12 in all three E. coli isolates. CTX-M-12 had a more potent hydrolytic activity against cefotaxime than against ceftazidime and was encoded on a self-transferable
18 kbp plasmid.
Conclusions: This work shows that CTX-M-12, which confers high-level resistance to cefotaxime but not to ceftazidime, has emerged in Korea. The blaCTX-M-12 gene was associated with an upstream ISEcp1 insertion sequence.
Keywords: ISEcp1 , horizontal transfer , ERIC-PCR