Antibiotic Resistance in Escherichia coli from Pigs in Organic and Conventional Farming in Four European Countries

PLoS One. 2016 Jun 30;11(6):e0157049. doi: 10.1371/journal.pone.0157049. eCollection 2016.

Abstract

Organic pig production differs in many ways from conventional production of pigs, e.g., in antibiotic use, herd structure, feeding regimes, access to outdoor areas and space allowance per pig. This study investigated if these differences result in a lower occurrence of antibiotic resistance in organic slaughter pigs in Denmark, France, Italy and Sweden. Samples were taken from the colon content and/or faeces and minimum inhibitory concentrations (MIC) of ten antibiotics were determined in isolates of Escherichia coli. In addition, the proportion of tetracycline (TET) resistant E. coli in colon content and/or faeces from individual pigs was determined. In all four countries the percentage resistance to ampicillin, streptomycin, sulphonamides or trimethoprim was significantly lower in E. coli from organic pigs. In France and Italy, the percentage of isolates resistant to chloramphenicol, ciprofloxacin, nalidixic acid or gentamicin was also significantly lower in the E. coli from organic pigs. Resistance to cefotaxime, was not found in any country. The percentage of E. coli isolates resistant to TET as well as the proportion of TET-resistant E. coli was significantly lower in organic than in conventional pigs, except in Sweden where TET-resistance was equally low in both production types. There were also differences between countries within production type in the percentage resistance to individual antibiotics as well as the proportion of TET-resistant E. coli with lower median proportions in Sweden and Denmark compared to France and Italy. The study shows that in each of the four countries resistance in intestinal E. coli was less common in organic than in conventional pigs, but that there were also large differences in resistance between countries within each production type, indicating that both country- and production-specific factors influence the occurrence of resistance.

MeSH terms

  • Agriculture
  • Animals
  • Anti-Bacterial Agents / pharmacology*
  • Drug Resistance, Bacterial / drug effects*
  • Escherichia coli / isolation & purification*
  • Europe
  • Feces / microbiology
  • Swine

Substances

  • Anti-Bacterial Agents

Grants and funding

The authors gratefully acknowledge the financial support of the CORE Organic II Funding Bodies, partners of the FP7 ERA-Net project, CORE Organic II (Coordination of European Transnational Research in Organic Food and Farming systems, project no. 249667). For further information see: (www.coreorganic2.org). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.