Emergence of CTX-M-12 extended-spectrum beta-lactamase-producing Escherichia coli in Korea.
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.
Bae
Il Kwon
IK
Department of Laboratory Medicine, Kosin University College of Medicine, 602-030, 34 Amnam-Dong, Suh-Gu, Busan, Korea.
Lee
You-Nae
YN
Hwang
Hyun Yong
HY
Jeong
Seok Hoon
SH
Lee
Su Jin
SJ
Kwak
Hyo-Sun
HS
Song
Wonkeun
W
Kim
Hyoung Jin
HJ
Youn
Hasik
H
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
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