Extended-spectrum and AmpC β-lactamase-producing Escherichia Coli in Broilers and People Living and/or Working on Broiler Farms: Prevalence, Risk Factors and Molecular Characteristics

J Antimicrob Chemother. 2014 Oct;69(10):2669-75. doi: 10.1093/jac/dku178. Epub 2014 May 30.

Abstract

Objectives: The objectives of this study were to: estimate the prevalence of extended-spectrum β-lactamase (ESBL)- and AmpC β-lactamase-producing Escherichia coli carriage among broiler farmers, their family members and employees; identify and quantify risk factors for carriage, with an emphasis on contact with live broilers; and compare isolates from humans and broilers within farms with respect to molecular characteristics to gain insight into transmission routes.

Methods: A cross-sectional prevalence study was conducted on 50 randomly selected Dutch broiler farms. Cloacal swabs were taken from 20 randomly chosen broilers. Faecal swabs were returned by 141 individuals living and/or working on 47 farms. ESBL/AmpC-producing E. coli were isolated and, for selected isolates, phylogenetic groups, plasmids and sequence types were determined. Questionnaires were used for risk factor analysis.

Results: All sampled farms were positive, with 96.4% positive pooled broiler samples. The human prevalence was 19.1%, with 14.3% and 27.1% among individuals having a low and a high degree of contact with live broilers, respectively. Five pairs of human-broiler isolates had identical genes, plasmid families and E. coli sequence types, showing clonal transmission. Furthermore, similar ESBL/AmpC genes on the same plasmid families in different E. coli sequence types in humans and broilers hinted at horizontal gene transfer.

Conclusions: The prevalence among people on broiler farms was higher than in previous studies involving patients and the general population. Furthermore, an increased risk of carriage was shown among individuals having a high degree of contact with live broilers. The (relative) contribution of transmission routes that might play a role in the dissemination of ESBL/AmpC-encoding resistance genes to humans on broiler farms should be pursued in future studies.

Keywords: ESBLs; MLST; carriage; phylogenetic groups; plasmids.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Agriculture
  • Animals
  • Bacterial Proteins / genetics*
  • Chickens
  • Child
  • Child, Preschool
  • Cross-Sectional Studies
  • Escherichia coli / classification
  • Escherichia coli / genetics*
  • Escherichia coli / isolation & purification
  • Escherichia coli Infections / epidemiology*
  • Escherichia coli Infections / microbiology*
  • Female
  • Humans
  • Infant
  • Infant, Newborn
  • Male
  • Middle Aged
  • Multilocus Sequence Typing
  • Netherlands
  • Phylogeny
  • Poultry Diseases / epidemiology*
  • Poultry Diseases / microbiology*
  • Prevalence
  • Risk Factors
  • Young Adult
  • beta-Lactamases / genetics*

Substances

  • Bacterial Proteins
  • AmpC beta-lactamases
  • beta-Lactamases