High prevalence of blaCTX-M extended-spectrum β-lactamase genes in Escherichia coli isolates from pets and emergence of CTX-M-64 in China

Y. Sun, Z. Zeng, Sheng Chen, J. Ma, L. He, Y. Liu, Y. Deng, T. Lei, J. Zhao, J. H. Liu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

127 Citations (Scopus)


As a cause of community-acquired infections, extended-spectrum β-lactamase (ESBL)-producing Escherichia coli constitute an emerging public-health concern. Few data on the molecular epidemiology of ESBL-producing E. coli isolates from pets are available in China. Detection and characterization of ESBL genes (blaCTX-M, blaSHVand blaTEM) was conducted among 240 E. coli isolates recovered from healthy and sick pets in South China from 2007 to 2008. The clonal relatedness of ESBL-producing E. coli isolates was assessed by pulsed field gel electrophoresis. ESBL-encoding genes were identified in 97 (40.4%) of the 240 isolates and 96 (40.0%) of them harbored CTX-M. The most common CTX-M types were CTX-M-14 (n = 45) and CTX-M-55 (n = 24). The recently reported CTX-M-64 was identified in three isolates. Isolates producing CTX-M-27, -15, -65, -24, -3 and -9 were also identified. Ten isolates carried two or three CTX-M types, with the combination of CTX-M-14 and CTX-M-55 being the most frequent (n = 6). ISEcp1 was identified in the upstream region of 93 out of the 107 blaCTX-Mgenes (86.9%). The sequence of the spacer region (45 bp) between ISEcp1 and the start codon of all blaCTX-M-55genes (except four) was identical to that of blaCTX-M-64. No major clonal relatedness was observed among these CTX-M producers. It is suggested that the horizontal transfer of blaCTX-Mgenes, mediated by mobile elements, contributes to their dissemination among E. coli isolates from pets. Our finding of high prevalence of ESBL in E. coli of companion animal origin illustrates the importance of molecular surveillance in tracking CTX-M-producing E. coli strains in pets. Journal Compilation
Original languageEnglish
Pages (from-to)1475-1481
Number of pages7
JournalClinical Microbiology and Infection
Issue number9
Publication statusPublished - 1 Jan 2010


  • Antimicrobial resistance
  • China
  • CTX-M
  • Escherichia coli
  • Extended-spectrum β-lactamases
  • Molecular epidemiology
  • Pets

ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases

Cite this