Detection of CTX-M-15, CTX-M-22, and SHV-2 extended-spectrum beta-lactamases (ESBLs) in Escherichia coli fecal-sample isolates from pig farms in China

Foodborne Pathog Dis. 2009 Apr;6(3):297-304. doi: 10.1089/fpd.2008.0164.


The aim of the present study was to investigate the antibiotic resistance profiles and the molecular epidemiology of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli isolates from two production swine operations in Sichuan Province, China, between August 2002 and February 2007. The prevalence of ESBL-producing E. coli increased dramatically from 2.2% to 10.7% during this period. This increase appeared mostly related to dissemination of CTX-M-type ESBLs among E. coli isolates. Of 212 E. coli isolates studied, 14 harbored ESBL genes. Among them, 13 harbored bla(CTX-M-15/22) and one harbored bla(SHV-2). To our knowledge, this is the first study to identify bla(CTX-M-22) from production animals. One isolate in 2002 harbored bla(SHV-2), indicating that ESBL genes have been present in farm animals in China since at least 2002. Molecular characterization and pulsed-field gel electrophoresis of the ESBL-producing isolates suggested that different mechanisms may be involved in the dissemination of the CTX-M genes and revealed that additional resistance determinants for non-beta-lactam antibiotics were carried by plasmids encoding certain ESBL genes. Results of this study provide an example of how ESBL genes, particularly those of CTX-M lineages, are rapidly spreading among E. coli isolates from commercial pig farms in Sichuan province of China.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Agriculture
  • Animals
  • Base Sequence
  • China
  • Conjugation, Genetic
  • DNA, Bacterial / analysis
  • Drug Resistance, Bacterial
  • Electrophoresis, Gel, Pulsed-Field
  • Escherichia coli / enzymology*
  • Escherichia coli / genetics
  • Escherichia coli / isolation & purification
  • Escherichia coli Proteins / analysis*
  • Escherichia coli Proteins / genetics
  • Feces / microbiology*
  • Plasmids / genetics
  • Polymerase Chain Reaction
  • Swine / microbiology*
  • beta-Lactam Resistance / genetics
  • beta-Lactamases / analysis*
  • beta-Lactamases / genetics


  • DNA, Bacterial
  • Escherichia coli Proteins
  • beta-lactamase CTX-M-15
  • beta-lactamase SHV-2
  • beta-Lactamases
  • beta-lactamase CTX-M-22, E coli