Characterization of two plasmid-encoded cefotaximases found in clinical Escherichia coli isolates: CTX-M-65 and a novel enzyme, CTX-M-87.
Three clinical strains of Escherichia coli (p168, p517 and p667) were collected in 2006 from three hospitals in Anhui Province (China). PCR and DNA sequencing revealed that E. coli p168 carried a novel extended-spectrum beta-lactamase (ESBL), which was designated CTX-M-87. The extended-spectrum beta-lactamase which was carried by E. coli p517 and E. coli p667 was previously named CTX-M-65. The deduced amino acid sequence of CTX-M-87, with pI 9.1, differed from that of CTX-M-14 by the substitutions Ala77-->Val and Pro167-->Leu. Like CTX-M-14, CTX-M-87 had a more potent hydrolytic activity against cefotaxime than against ceftazidime and had high affinity for cefuroxime and cefotaxime. These data show that mutations at position 167 in CTX-M do not always affect catalytic activity and substrate preference.
Yin
Jun
J
Department of Infectious Diseases, First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230022, PR China.
Cheng
Jun
J
Department of Infectious Diseases, First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230022, PR China.
Sun
Zhen
Z
Department of Infectious Diseases, First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230022, PR China.
Ye
Ying
Y
Department of Infectious Diseases, First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230022, PR China.
Gao
Yu-Feng
YF
Department of Infectious Diseases, First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230022, PR China.
Li
Jia-Bin
JB
Clinical Medicine Post-Doctorate Position of Anhui Medical University, Hefei, Anhui 230032, PR China.|Department of Infectious Diseases, First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230022, PR China.
Zhang
Xue-Jun
XJ
Institute of Dermatology, Anhui Medical University, Hefei, Anhui 230032, PR China.|Clinical Medicine Post-Doctorate Position of Anhui Medical University, Hefei, Anhui 230032, PR China.
D019943:Amino Acid Substitution; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002439:Cefotaxime / Q000494:pharmacology*; D002681:China / Q000453:epidemiology; D003001:Cloning, Molecular; D003227:Conjugation, Genetic; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology; D006801:Humans; D007700:Kinetics; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics*; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
D000900:Anti-Bacterial Agents; C071167:beta-lactamase CTX-2; D001618:beta-Lactamases; D002439:Cefotaxime