Emergence of CTX-M-12 extended-spectrum β-lactamase-producing Escherichia coli in Korea

Il Kwon Bae, You Nae Lee, Hyun Yong Hwang, Seok Hoon Jeong, Su Jin Lee, Hyo Sun Kwak, Wonkeun Song, Hyoung Jin Kim, Hasik Youn

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13 Citations (Scopus)


Objectives: To characterize CTX-M-12 extended-spectrum β-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 β-lactamases was performed by PCR amplification, and the genetic environments of the bla CTX-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 IS Ecp1 insertion sequence was located 49 bp upstream of bla CTX-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 IS Ecp1 insertion sequence.

Original languageEnglish
Pages (from-to)1257-1259
Number of pages3
JournalJournal of Antimicrobial Chemotherapy
Issue number6
Publication statusPublished - 2006 Dec

Bibliographical note

Funding Information:
This work was supported by a research grant from the Korea Food and Drug Administration (06042HangNaeMae129).

All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Microbiology (medical)
  • Infectious Diseases
  • Pharmacology (medical)


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