Prevalence of Yersinia in Antimicrobial-Free and Conventional Antimicrobial Use Pig Farms

In a study of farms across three states, around 11 per cent had pigs positive for the foodborne pathogen, Yersinia enterocolitica. The likelihood of positive pigs was higher on antibiotic-free farms than on those with a conventional antibiotic policy.
calendar icon 25 April 2013
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Pigs are the primary reservoir for foodborne illness associated with Yersinia enterocolitica, according to Julie A. Funk, DVM, MS, PhD of Michigan State University and co-authors at Ohio State University, North Carolina State University and Food and Drug Administration.

In a paper published online in Foodborne Pathogens and Disease, they explain that the use of antimicrobials in animal agriculture has been hypothesised as having a potential role in the increase in prevalence of zoonotic pathogens.

The objective of their study was to compare the frequency of Y. enterocolitica faecal shedding in pigs reared on farms with conventional antimicrobial use policies to farms that were antimicrobial-free (ABF).

The farms were selected from three regions in the United States. In each region, farms were categorised based on antimicrobial use policy. Faecal samples were collected from pigs on-farm within 48 hours of harvest.

The overall proportion of Y. enterocolitica and ail-harbouring Y. enterocolitica–positive pigs was 10.9 per cent and 4.0 per cent, respectively. There were increased odds (odds ratio [OR] 6.8; 95 per cent confidence interval [CI] 3.46–13.28) for a pig to be Y. enterocolitica-positive if it was reared on an ABF farm compared to a conventional farm.

There was no significant association between farm antimicrobial use policy and isolation of an ail-harbouring Y. enterocolitica from an individual pig (OR 1.8; 95 per cent CI 0.90–3.61).

Funk and her co-authors warned that the association of antimicrobial use policy with Y. enterocolitica shedding in faeces should be interpreted cautiously, as antimicrobial use cannot be separated from other management factors (e.g. confinement or outdoor housing), which may be associated with risk of Y. enterocolitica in pigs.


Funk J.A., M.J. Abley, A.S. Bowman, W.A. Gebreyes, W.E. Morgan Morrow and D.A. Tadesse. 2013. Prevalence of Yersinia enterocolitica in antimicrobial-free and conventional antimicrobial use swine production. Foodborne Pathogens and Disease. ahead of print. doi:10.1089/fpd.2012.1354

Further Reading

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April 2013

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