Colonised livestock transmit MRSA to farmers

4 January 2013 by Stephanie Swift, posted in Disease, Microorganisms, Science

These days, most people are aware of the increasing development of antibiotic resistance in bacteria that cause human disease, which is at least partially driven by the overprescription of antibiotics. Even our most robust antibiotics, active against a wide range of bacterial species, are not up to the task of controlling certain infections, making the push to develop new ones - or antibiotic alternatives - particularly compelling. One exceptionally well-publicised antibiotic-insensitive bacteria is the methicillin-resistant Staphylococcus aureus (MRSA), which spreads throughout hospitals, communities and, interestingly, farms.

The first reports of livestock-associated MRSA (LA-MRSA) were published in 2003, after being isolated from Dutch pigs. From there, it was identified in pigs across Europe, in Singapore and in North America. And it wasn't only pigs becoming colonised, either: in the United Kingdom in 2009, LA-MRSA was identified in horses, and towards the end of 2012, in the cattle population. Unfortunately, livestock don't keep these social microorganisms to themselves - the bacteria are more than happy to transfer onto humans coming into contact with carrier animals. Although the prevalence of LA-MRSA in the general human population is low, there is certainly evidence for it causing disease in people closely associated with agriculture and livestock. In one Dutch study, around 38% of cattle farmers were colonised with LA-MRSA, and the bacteria were more prevalent after longer periods of time spent around animals.

While the appearance of this bacteria in food-producing animals and the substantial exposure risk for people who work with them is a definite public health concern, following healthy guidelines in the preparation and consumption of animal products - such as only drinking pasteurised milk and checking that meat is thoroughly cooked -  should ensure that LA-MRSA has little general human impact.

3 Responses to “Colonised livestock transmit MRSA to farmers”

  1. Sedona Reply | Permalink

    I could not agree more with the author of this post. I think we have only seen the tip of the iceberg as it concerns staph, and other antibiotic resistant issues. If it wasn't for the work of Microbiologist, Michelle Moore, I don't think my father would have seen the light of day again, after his last stay in the hospital. Fortunately Michelle saw the need for solutions beyond drugs, and put her most useful educational background to good use. For anyone else who may need a solution for staph, check out the information on her site ( Great post. Keep up the good work!!

  2. Khalil A. Cassimally Reply | Permalink

    You say that "around 38% of cattle farmers were colonised with LA-MRSA" in a Dutch study. Any idea what proportion of those infected actually show symptoms (or get sick)?

    • Stephanie Swift Reply | Permalink

      In that particular study, they didn't look at how being colonised with LA-MRSA translated into getting sick. There's actually very little information about illness directly caused by LA-MRSA, apart from a few cases of skin lesions, ulcers, pneumonia and various inflammatory infections in farm workers. Having said that, one fairly robust Dutch study ( has estimated that ~50% of people colonised with LA-MRSA will experience some sort of skin or soft tissue infection. But as with any other MRSA, good hygienic practises can go a long way to minimise that risk.

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