MRSA Can Spread Through Contact With Livestock
October 11, 2012

Proximity To Livestock Spreads Pathogens Like MRSA

Connie K. Ho for — Your Universe Online

Researchers from Johns Hopkins University Bloomberg School of Public Health, the Dutch Institute for Public Health and the Environment (RIVM), and the VU University Medical Center Amsterdam recently found that people who reside near livestock could be at an increased risk of contracting Methicillin-resistant Staphylococcus aureus (MRSA).

According to researchers, Staphylococcus aureus can lead to respiratory, urinary, skin, and bloodstream infections of humans. The U.S. Centers for Disease Control and Prevention (CDC) reported that the bacteria is resistant to penicillin and beta-lactams, a type of first-line antibiotics. Livestock association (LA) MRSA infections are most commonly found with skin infections. The study included a comparison of livestock density, place of residence, along with information no risk factors.

"In the past, MRSA has been largely associated with hospitals and other health care facilities, but in the last decade the majority of infections have been acquired in the community outside of a health care setting," explained the study´s co-author Ellen Silbergeld, a professor with the Bloomberg School of Public Health's Department of Environmental Health Sciences, in a prepared statement.

The authors of the paper believe that the study is the first to propose that transmission of pathogens can occur due to proximity with livestock.

"In the Netherlands LA-MRSA was first found in 2003 and was initially almost exclusively found in persons with direct contact to livestock. In recent years LA-MRSA is found with increasing frequency in community-dwelling individuals with no known contact with livestock,” remarked the study´s co-author Dr. Jan Kluytmans, a professor of Medical Microbiology and Infection Control at VU University Medical Center Amsterdam, in the statement. “It is important to determine the routes of transmission outside of the farms since this may have important consequences for public health.”

The group utilized existing data on livestock and population densities as well as livestock-associated MRSA carriage. They analyzed the effect that regional-level factors could have in person´s risk for the disease, after taking into consideration individual risk factors like living conditions (i.e. urban or rural setting), the context of MRSA contraction, and the amount of personal contact with animals.

"Using logistic regression, we found that as the density of veal calves, pigs, or cattle doubles in a specific area, the odds of carrying LA-MRSA increases between 24 percent and 77 percent, depending on the animal. These results challenge us to understand how these exposures could be occurring," noted lead author Dr. Beth Feingold, a Bloomberg School of Public Health graduate, in the statement. "This work has potential policy implications for MRSA surveillance in countries with a substantial percentage of total MRSA cases being livestock-associated MRSA. Controlling the spread of livestock-associated MRSA requires attention to community members in animal-dense regions who are otherwise unaffiliated with livestock farming."

The authors believe that, while the study has implications in the Netherlands, it could also affect the population in the U.S. They recommend that future studies look into the correlation between livestock operations in the U.S. along with microbes that are considered drug resistant.

The study´s findings are featured in the November issue of Emerging Infectious Diseases.