Abstract
Objectives: To characterize a novel ceftazidime-hydrolysing CTX-M mutant, designated CTX-M-54, produced by Klebsiella pneumoniae clinical isolate BDK0419 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 organization of the blaCTX-M-54 gene was investigated by PCR and sequencing of the regions surrounding this gene. Kinetic parameters were determined from purified CTX-M-54. Results: The strain BDK0419 contained a transferable plasmid with a molecular size of ∼21 kbp that carries both blaSHV-2a and blaCTX-M-54 β-lactamase genes, along with two other plasmids. The blaCTX-M-54 gene was flanked upstream by an IS Ecp1 insertion sequence and downstream by an IS 903-like element. CTX-M-54 had a P167Q substitution within the omega loop region of class A β-lactamases compared with the sequence of CTX-M-3. The MIC of ceftazidime for K. pneumoniae BDK0419 was 16-fold higher than that of cefotaxime; however, the kinetic parameter of CTX-M-54 against ceftazidime revealed a low catalytic efficiency. Conclusions: This work shows once again that novel CTX-M enzymes with an expanded activity towards ceftazidime through a single amino acid substitution can be identified from clinical isolates. Thus, detection of CTX-M enzymes can no longer be based solely on the resistance phenotypes of clinical isolates towards ceftazidime and cefotaxime.
| Original language | English |
|---|---|
| Pages (from-to) | 315-319 |
| Number of pages | 5 |
| Journal | Journal of Antimicrobial Chemotherapy |
| Volume | 58 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 2006 Aug 1 |
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All Science Journal Classification (ASJC) codes
- Pharmacology
- Pharmacology (medical)
- Infectious Diseases
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A novel ceftazidime-hydrolysing extended-spectrum β-lactamase, CTX-M-54, with a single amino acid substitution at position 167 in the omega loop. / Bae, Kwon; Lee, Byung Ho; Hwang, Hyun Yong; Jeong, Seok Hoon; Hong, Seong Geun; Chang, Chulhun L.; Kwak, Hyo Sun; Kim, Hyoung Jin; Youn, Hasik.
In: Journal of Antimicrobial Chemotherapy, Vol. 58, No. 2, 01.08.2006, p. 315-319.Research output: Contribution to journal › Article
TY - JOUR
T1 - A novel ceftazidime-hydrolysing extended-spectrum β-lactamase, CTX-M-54, with a single amino acid substitution at position 167 in the omega loop
AU - Bae, Kwon
AU - Lee, Byung Ho
AU - Hwang, Hyun Yong
AU - Jeong, Seok Hoon
AU - Hong, Seong Geun
AU - Chang, Chulhun L.
AU - Kwak, Hyo Sun
AU - Kim, Hyoung Jin
AU - Youn, Hasik
PY - 2006/8/1
Y1 - 2006/8/1
N2 - Objectives: To characterize a novel ceftazidime-hydrolysing CTX-M mutant, designated CTX-M-54, produced by Klebsiella pneumoniae clinical isolate BDK0419 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 organization of the blaCTX-M-54 gene was investigated by PCR and sequencing of the regions surrounding this gene. Kinetic parameters were determined from purified CTX-M-54. Results: The strain BDK0419 contained a transferable plasmid with a molecular size of ∼21 kbp that carries both blaSHV-2a and blaCTX-M-54 β-lactamase genes, along with two other plasmids. The blaCTX-M-54 gene was flanked upstream by an IS Ecp1 insertion sequence and downstream by an IS 903-like element. CTX-M-54 had a P167Q substitution within the omega loop region of class A β-lactamases compared with the sequence of CTX-M-3. The MIC of ceftazidime for K. pneumoniae BDK0419 was 16-fold higher than that of cefotaxime; however, the kinetic parameter of CTX-M-54 against ceftazidime revealed a low catalytic efficiency. Conclusions: This work shows once again that novel CTX-M enzymes with an expanded activity towards ceftazidime through a single amino acid substitution can be identified from clinical isolates. Thus, detection of CTX-M enzymes can no longer be based solely on the resistance phenotypes of clinical isolates towards ceftazidime and cefotaxime.
AB - Objectives: To characterize a novel ceftazidime-hydrolysing CTX-M mutant, designated CTX-M-54, produced by Klebsiella pneumoniae clinical isolate BDK0419 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 organization of the blaCTX-M-54 gene was investigated by PCR and sequencing of the regions surrounding this gene. Kinetic parameters were determined from purified CTX-M-54. Results: The strain BDK0419 contained a transferable plasmid with a molecular size of ∼21 kbp that carries both blaSHV-2a and blaCTX-M-54 β-lactamase genes, along with two other plasmids. The blaCTX-M-54 gene was flanked upstream by an IS Ecp1 insertion sequence and downstream by an IS 903-like element. CTX-M-54 had a P167Q substitution within the omega loop region of class A β-lactamases compared with the sequence of CTX-M-3. The MIC of ceftazidime for K. pneumoniae BDK0419 was 16-fold higher than that of cefotaxime; however, the kinetic parameter of CTX-M-54 against ceftazidime revealed a low catalytic efficiency. Conclusions: This work shows once again that novel CTX-M enzymes with an expanded activity towards ceftazidime through a single amino acid substitution can be identified from clinical isolates. Thus, detection of CTX-M enzymes can no longer be based solely on the resistance phenotypes of clinical isolates towards ceftazidime and cefotaxime.
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U2 - 10.1093/jac/dkl252
DO - 10.1093/jac/dkl252
M3 - Article
C2 - 16785225
AN - SCOPUS:33748063296
VL - 58
SP - 315
EP - 319
JO - Journal of Antimicrobial Chemotherapy
JF - Journal of Antimicrobial Chemotherapy
SN - 0305-7453
IS - 2
ER -