A new study on livestock production and drug resistance released Tuesday by the journal PLOS ONE supports findings from earlier studies in Iowa showing greater risk for employees around antibiotics.

Study results are based on a collection of nose swabs from workers at two North Carolina farms. One was a livestock operation where animals were raised in large confinement buildings using antibiotics, the other farm primarily kept animals on pastures and grew livestock without the use of antibiotics.

According to Science Daily, results of the study show drug-resistant bacteria associated with livestock in the noses of industrial livestock workers, but not in the noses of workers from the other farm. The bacteria observed were Staphylococcus aureus, which includes the well-known bug MRSA.

The study found the livestock operators working in large confinement buildings were twice as likely to have S. aureus that is multidrug-resistant compared to the other farm.

"This study shows that these livestock-associated strains are present among workers at industrial livestock operations and that these strains are resistant not just to methicillin, but to multiple antibiotics -- including antibiotics that are used to treat human infections," said Christopher Heaney, PhD, corresponding author of the study and assistant professor of Environmental Health Sciences and Epidemiology at the Johns Hopkins Bloomberg School of Public Health.

The study was conducted by researchers by Johns Hopkins Bloomberg School of Public Health and the University of North Carolina at Chapel Hill, along with the Rural Empowerment Association for Community Help, the George Washington University, and the Statens Serum Institute.

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