Distribution of blaCTX-M-gene variants in E. coli from different origins in Ecuador

Xavier Valenzuela, Hayden Hedman, Alma Villagomez, Paul Cardenas, Joseph N.S. Eisenberg, Karen Levy, Lixin Zhang, Gabriel Trueba

Research output: Contribution to journalArticlepeer-review


The increasing abundance of extended spectrum β-lactamase (ESBL) genes in E. coli, and other commensal and pathogenic bacteria, endangers the utility of third or more recent generation cephalosporins, which are major tools for fighting deadly infections. The role of domestic animals in the transmission of ESBL carrying bacteria has been recognized, especially in low- and middle-income countries, however the horizontal gene transfer of these genes is difficult to assess. Here we investigate blaCTX-M gene diversity (and flanking nucleotide sequences) in E. coli from chicken and humans, in an Ecuadorian rural community and from chickens in another location in Ecuador. The blaCTX-M associated sequences in isolates from humans and chickens in the same remote community showed greater similarity than those found in E. coli in a chicken industrial operation 200 km away. Our study may provide evidence of blaCTX-M transfer between chickens and humans in the community.

Original languageEnglish
Article number100092
JournalMedicine in Microecology
StatePublished - Dec 2023


  • Antimicrobial resistance
  • Chickens
  • E. coli
  • Ecuador
  • ISEcp1, spacer sequence
  • Third-generation cephalosporin resistance (TGCR)
  • bla


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