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If you walk this line, you might just get MRSA in your nose. Farm Sanctuary/Flickr

Factory-scale farms don’t just house hundreds of genetically similar animals in tight quarters over vast cesspools collecting their waste. They also house a variety of bacteria that live within those unfortunate beasts’ guts. And when you dose the animals daily with small amounts of antibiotics-a common practice-the bacteria strains in these vast germ reservoirs quite naturally develop the ability to withstand anti-bacterial treatments.

Antibiotic-resistant bacteria leave these facilities in two main ways. The obvious one is meat: As Food and Drug Administration datashows, the pork chops, chicken parts, and ground beef you find on supermarket shelves routinely carry resistant bacteria strains. But there’s another, more subtle way: through the people who work on these operations.

In a new paper, a team of researchers from Johns Hopkins and the University of North Carolina-Chapel Hill took nasal swabs from 22 North Carolina hog facility workers over 14 days. The results: 10 of them proved to be “persistent” carriers of a strain of bacteria associated with livestock called
Staphylococcus aureus-that is, they carried for up to four days after their last day at work. Of those 10, 7 of the workers carried a form of
Staphylococcus aureus that’s resistant to one or more antibiotics.

The researchers report that their study is the first to test the persistence of the bacteria strains that workers pick up at livestock farms. “Researchers had believed that livestock-associated bacteria would clear from the noses of hog workers quickly-within 24 hours,” the press release accompanying the report states. Apparently, not so much.