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MRSA found in U.S. pig farms

By Jessica Centers

A recent study shows that methicillin-resistant staphylococcus aureus — a potentially deadly bacteria — is not only present, but common, in U.S. pigs and farm workers, raising concerns about the safety of pork.

MRSA gained attention last year after it started popping up in schools and gyms, and a 17-year-old in Virginia died from an infection. The antibiotic-resistant form of staph bacteria had previously only been found in hospital settings. Then in October, a study in the Journal of the American Medical Association reported that more than 90,000 Americans contract invasive MRSA infections each year, with 18,000 of those cases resulting in death — more than the annual AIDS death toll in this country. Despite that finding and the fact that the bacteria has been found in livestock and farm workers in Europe, Scandinavia and Canada, the U.S. government does not test animals for MRSA.

Earlier this year, Tara Smith, an assistant professor at the University of Iowa Department of Epidemiology, and a team of graduate students took it upon themselves to see if U.S. livestock carry MRSA. They conducted nasal swabs of 299 pigs on 10 farms representing two companies in Iowa and Illinois. Though their work has yet to be published, their results were presented at the American Society for Microbiology annual meeting in Boston earlier this month, and first reported by the Seattle Post Intelligencer last week.

According to Smith's abstract, MRSA was present in 49 percent of the pigs. When broken down by age, the bacteria was present in 36 percent of the adult pigs and 100 percent of swine nine to 12 weeks. Of 20 farm workers also tested, nine were positive for MRSA. "These results show that colonization of swine by MRSA is very common on the farm system we examined in the Midwestern U.S., adding to the concern about domestic animal species as a reservoir of this bacterium," the abstract reads.

Rebecca Goldburg, a senior scientist with the Environmental Defense Fund, says those findings raise concerns about the heavy routine use of antibiotics in U.S. hog production, which the EDF advocates ending. "I think it shows what's been well documented in Europe and Canada is occurring in the U.S., too, and that is there is a strain of MRSA bacteria associated with pigs and probably other livestock, too, that's common in the U.S. And, we know from Europe, that [it} makes people very sick."

Citing research from Scott Weese of the Department of Pathobiology at the Ontario Veterinary College, who earlier this year found MRSA in 10 percent of 212 pork chop and ground pork samples in Canada, Goldburg says there's no reason to think U.S. pork is any better.

Most alarming, she says, is that MRSA is not just a foodborne bacteria. It can cause infections topically. "There's no good data about prevalence of MRSA on organic farms, but I would tend to buy from those sorts of systems and then I would treat pork really carefully, when I handle it especially," Goldburg says.

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