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Member Research & Reports

Member Research & Reports

Iowa Researchers Find Swine Farming is a Risk Factor for Drug-resistant Staph Infections

Swine farmers are more likely to carry multidrug-resistant Staphylococcus aureus (S. aureus or “staph”) than people without current swine exposure, according to a study conducted by a team of researchers from the University of Iowa, Kent State University, and the National Cancer Institute.

Tara Smith
[Photo: Dr. Tara Smith]

The study, published online in the journal Clinical Infectious Diseases, is the largest prospective examination of S. aureus infection in a group of livestock workers worldwide, and the first such study in the United States.

“Current swine workers were six times more likely to carry multidrug-resistant S. aureus than those study participants without current swine exposure,” says Dr. Tara Smith. The study is based on research that Smith, currently an associate professor at Kent State University, conducted while she was a faculty member at the UI College of Public Health.

S. aureus is a type of bacteria commonly found on the skin as well as in the noses and throats of people and animals. About 30 percent of the U.S. population carries these bacteria, which can cause a range of skin and soft tissue infections. Although most infections are minor, S. aureus can sometimes cause serious infections.

Increasingly, drug-resistant strains of S. aureus are emerging, including methicillin-resistant (MRSA), tetracycline-resistant (TRSA), or multidrug-resistant (MDRSA) strains. And while previous studies have shown that certain strains of S. aureus are often associated with swine, cattle, and poultry exposure, little is known about livestock-associated staph carriage and infection in the United States.

The study authors note the research helps keep farmers safe by raising awareness about a potential health issue in swine operations. S. aureus does not present an economic concern for swine farmers since pigs generally are unaffected by staph infections.

“S. aureus does not typically make pigs sick, but they can act as carriers and transmit the bacterium to farmers,” says Dr. Smith. “While carriage of S. aureus isn’t itself harmful, individuals who harbor the bacterium in their nose, throat, or on their skin are at risk of developing an active staph infection, and they can also pass the bacterium to other family or community members. Individuals who may be immunocompromised, or have existing conditions such as diabetes, are especially at risk from staph infections.”

Study co-investigators included Shylo E. Wardyn, Brett M. Forshey, Sarah Farina, Ashley E. Kates, Rajeshwari Nair, Megan Quick, James Y. Wu, Blake Hanson, Sean O’Malley, Hannah W. Shows, Ellen M. Heywood, Charles F. Lynch, and Margaret Carrel from the University of Iowa and Laura E. Beane-Freeman from the National Cancer Institute.

This work was supported in part by the intramural research program of the National Institutes of Health, National Cancer Institute [Z01-CP010119], and by the Agency for Healthcare Research and Quality [R18 HS019966].

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