• John Evans

MRSA risk up to 12 times as high in livestock workers


Photo by AnemoneProjectors via Wikimedia Commons

People who work with livestock, including veterinarians, are at a significantly higher risk than the general population for colonization and infection with methicillin-resistant Staphylococcus aureus (MRSA).


This finding comes from a paper published in the journal Occupational and Environmental Medicine (Online ahead of print Oct. 23, 2020).


“This is a bit of a wake-up call,” said study author Felicia Wu, PhD, in a press release from Michigan State University (MSU) in East Lansing, Mich. “I don’t think there was much awareness that swine workers are at such high risk, for example. Or that large animal vets are also at extremely high risk.”


Dr. Wu is the John. A Hannah Distinguished Professor in the Departments of Food Science and Human Nutrition and Agricultural, Food and Resource Economics at MSU.


In the study, Dr. Wu and her colleagues screened the PubMed and Embase databases for studies published from 2005 to 2019 that reported livestock-associated (LA)-MRSA colonization and infection among livestock workers/veterinarians, their families, and community members not regularly exposed to livestock.


Among their findings, they noted that compared with individuals who do not work with animals, those working on swine farms are more than 15 times more likely to harbour MRSA, acquired from livestock. Cattle workers were nearly 12 times as likely to harbour it, and livestock veterinarians were roughly eight times as likely to.


“Livestock-associated MRSA is a strain of MRSA that is especially infectious among animals. Now it has evolved to infect humans as well,” said Dr. Wu. “Bacteria have shown an amazing ability to jump across species to colonize and cause infections.”


The authors note that the livestock-associated variant of MRSA, first documented in the early 2000s, appears to be less dangerous to humans than MRSA that evolved in health care settings, where it built up defenses against a range of antibiotics.


Further, the livestock-associated strain also appears to be less prevalent than community-associated MRSA strains, which are often encountered in gyms, schools and workplaces and are typically more treatable than their counterparts found in hospitals and doctors’ offices.


In the paper, Dr. Wu and her colleagues also note that some steps have been taken to try and reduce the development of antibiotic-resistant bacteria in livestock. In particular, in 2017 the U.S. Food and Drug Administration (FDA) forbade the use of antibiotics to spur animal growth.


The authors also make several recommendations to reduce the risk of colonization and infection to livestock workers. These include:

  • Reducing the exposure of broken skin to the environment

  • Keeping cuts and open wounds clean and covered

  • Regular hand washing and

  • Wearing gloves and protective clothing

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