CTX-M type beta-lactamases among fecal Escherichia coli and Klebsiella pneumoniae isolates in non-hospitalized children and adults

J Microbiol Immunol Infect. 2008 Oct;41(5):428-32.


We investigated the occurrence and diversity of extended-spectrum beta-lactamase (ESBL) enzymes among antibiotic-resistant Escherichia coli and Klebsiella pneumoniae isolates obtained from human feces. All ESBL-positive isolates were characterized at the molecular level by polymerase chain reaction, sequencing and pulsed-field gel electrophoresis (PFGE). Eight of 46 antibiotic-resistant E. coli (6 from children and 2 from adults) and 4 of 8 K. pneumoniae (all from adults) isolates were found to be ESBL-positive by the double-disk synergy test. Seven isolates were found to have CTX-M-14, 2 each had CTX-M-24 and CTX-M-38, and 1 had CTX-M-9. In addition, 8 isolates were found to carry TEM-1b or TEM-1c. No SHV-type enzyme was found among the E. coli strains. In 9 strains, the plasmidic bla(CTX-M) determinants were transferable to E. coli by conjugation. Analysis by PFGE showed evidence of clonal and non-clonal spread. The present study shows fecal carriage of organisms producing bla(CTX-M) determinants and underscores the role that commensals could play as a reservoir for their dissemination.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cephalosporin Resistance / genetics*
  • Cephalosporinase / genetics*
  • Electrophoresis, Gel, Pulsed-Field
  • Escherichia coli / enzymology*
  • Escherichia coli / genetics
  • Escherichia coli / isolation & purification
  • Feces / microbiology*
  • Humans
  • Klebsiella pneumoniae / enzymology*
  • Klebsiella pneumoniae / genetics
  • Klebsiella pneumoniae / isolation & purification
  • Microbial Sensitivity Tests
  • Polymerase Chain Reaction
  • beta-Lactam Resistance / genetics
  • beta-Lactamases / genetics


  • Cephalosporinase
  • beta-Lactamases