Methicillin-resistant Staphylococcus Aureus and Extended-Spectrum and AmpC β-lactamase-producing Escherichia Coli in Broilers and in People Living and/or Working on Organic Broiler Farms

Vet Microbiol. 2015 Mar 23;176(1-2):120-5. doi: 10.1016/j.vetmic.2014.12.010. Epub 2014 Dec 19.


The aim of this study was to estimate the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum and AmpC β-lactamase (ESBL/AmpC)-producing Escherichia coli among broilers, and humans living and/or working on organic broiler farms; further characterise isolates; and compare these results with those from conventional farms. In the Netherlands, only 9 certified organic broiler farms were present. On 8 of these farms, 60 throat swabs and 20 cloacal swabs were taken per farm for MRSA and ESBL/AmpC-E. coli detection, respectively, at an average age of both 34 (T1) and 68 (T2) days. Faecal swabs and questionnaires were returned by 27 out of 36 humans. For selected ESBL/AmpC-producing E. coli isolates, phylogenetic groups, β-lactamase genes, plasmid families, and sequence types were determined. MRSA was not detected in broiler and human samples. ESBL/AmpC-producing E. coli were isolated from broilers on 7/8 farms at T1 and on all farms at T2. Furthermore, 3 farmers at T1, and 2 farmers and 1 family member at T2 were positive. Genes found in broilers and humans were almost exclusively blaCTX-M-1 and blaCMY-2. Given the high overall human ESBL/AmpC-prevalence (18.5%), which is similar to conventional farms, contact with live broilers is assumed a risk factor for carriage. Farm and sample-level prevalence at T1 are consistent with those from conventional farms. At T2, just before slaughter, sample-level prevalence of ESBL/AmpC-E. coli appears to have decreased (94.3% vs. 80%), which could have important consequences for contamination of retail meat.

Keywords: Broiler prevalence; ESBL; Human carriage; MRSA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animal Husbandry / methods*
  • Animals
  • Anti-Bacterial Agents / pharmacology*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Chickens / microbiology*
  • Drug Resistance, Bacterial
  • Escherichia coli / drug effects
  • Escherichia coli / enzymology
  • Escherichia coli / isolation & purification*
  • Escherichia coli Infections / veterinary
  • Humans
  • Methicillin-Resistant Staphylococcus aureus / isolation & purification*
  • Netherlands
  • Phylogeny
  • Prevalence
  • Zoonoses
  • beta-Lactamases / genetics
  • beta-Lactamases / metabolism*


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