High Prevalence of Extended-Spectrum Beta-Lactamase CTX-M-Producing Escherichia coli in Small-Scale Poultry Farming in Rural Ecuador

Am J Trop Med Hyg. 2019 Feb;100(2):374-376. doi: 10.4269/ajtmh.18-0173.


Small-scale farming may have large impacts on the selection and spread of antimicrobial resistance to humans. We conducted an observational study to evaluate antibiotic-resistant Escherichia coli populations from poultry and humans in rural northwestern Esmeraldas, Ecuador. Our study site is a remote region with historically low resistance levels of third-generation antibiotics such cefotaxime (CTX), a clinically relevant antibiotic, in both poultry and humans. Our study revealed 1) high CTX resistance (66.1%) in farmed broiler chickens, 2) an increase in CTX resistance over time in backyard chicken not fed antibiotics (2.3-17.9%), and 3) identical bla CTX-M sequences from human and chicken bacteria, suggesting a spillover event. These findings provide evidence that small-scale meat production operations have direct impacts on the spread and selection of clinically important antibiotics among underdeveloped settings.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Agriculture / methods
  • Animals
  • Anti-Bacterial Agents / pharmacology
  • Cefotaxime / pharmacology
  • Chickens
  • Drug Resistance, Multiple, Bacterial / genetics*
  • Ecuador / epidemiology
  • Escherichia coli / drug effects
  • Escherichia coli / enzymology
  • Escherichia coli / genetics*
  • Escherichia coli Infections / epidemiology
  • Escherichia coli Infections / microbiology
  • Escherichia coli Infections / transmission
  • Escherichia coli Infections / veterinary*
  • Escherichia coli Proteins / genetics*
  • Escherichia coli Proteins / metabolism
  • Gene Expression
  • Humans
  • Microbial Sensitivity Tests
  • Poultry
  • Poultry Diseases / epidemiology*
  • Poultry Diseases / microbiology
  • Poultry Diseases / transmission
  • Prevalence
  • beta-Lactam Resistance / genetics
  • beta-Lactamases / genetics*
  • beta-Lactamases / metabolism


  • Anti-Bacterial Agents
  • Escherichia coli Proteins
  • beta-Lactamases
  • beta-lactamase CTX-M, E coli
  • Cefotaxime