title: Emergence of CTX-M-12 extended-spectrum beta-lactamase-producing Escherichia coli in Korea.
abstract: OBJECTIVE
  To characterize CTX-M-12 extended-spectrum beta-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 beta-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 ISEcp1 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 approximately 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 bla(CTX-M-12) gene was associated with an upstream ISEcp1 insertion sequence.
authors.affiliation: Department of Laboratory Medicine, Kosin University College of Medicine, 602-030, 34 Amnam-Dong, Suh-Gu, Busan, Korea.
authors.forename: Il Kwon
authors.initials: IK
authors.lastname: Bae
authors.forename: You-Nae
authors.initials: YN
authors.lastname: Lee
authors.forename: Hyun Yong
authors.initials: HY
authors.lastname: Hwang
authors.forename: Seok Hoon
authors.initials: SH
authors.lastname: Jeong
authors.forename: Su Jin
authors.initials: SJ
authors.lastname: Lee
authors.forename: Hyo-Sun
authors.initials: HS
authors.lastname: Kwak
authors.forename: Wonkeun
authors.initials: W
authors.lastname: Song
authors.forename: Hyoung Jin
authors.initials: HJ
authors.lastname: Kim
authors.forename: Hasik
authors.initials: H
authors.lastname: Youn
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism; D002439:Cefotaxime / Q000378:metabolism; D002442:Ceftazidime / Q000378:metabolism; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D007700:Kinetics; D007723:Korea; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013379:Substrate Specificity; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D002442:Ceftazidime; C071167:beta-lactamase CTX-2; D001618:beta-Lactamases; D002439:Cefotaxime