Some hog workers developing drug-resistant skin infections

November 16, 2016

New Johns Hopkins Bloomberg School of Public Health-led research suggests that some workers at industrial hog production facilities are not only carrying livestock-associated, antibiotic-resistant bacteria in their noses, but may also be developing skin infections from these bacteria.

The findings are published Nov. 16 in PLOS ONE.

"Before this study, we knew that many hog workers were carrying livestock-associated and multidrug-resistant Staphylococcus aureus strains in their noses, but we didn't know what that meant in terms of worker health," says study leader Christopher D. Heaney, PhD, an assistant professor at the Bloomberg School's departments of Environmental Health and Engineering, and Epidemiology. "It wasn't clear whether hog workers carrying these bacteria might be at increased risk of infection. This study suggests that carrying these bacteria may not always be harmless to humans."

Because the study was small, the researchers say there is a need to confirm the findings, but the results highlight the need to identify ways to protect workers from being exposed to these bacteria on the job, and to take a fresh look at antibiotic use and resistance in food animal production. Hogs are given antibiotics in order to grow them more quickly for sale, and the overuse of antibiotics has been linked to the development of bacteria that are resistant to many of the drugs used to treat staph infections.

The researchers, involving collaborators at the University of North Carolina at Chapel Hill, the Rural Empowerment Association for Community Help in Warsaw, NC, and the Statens Serum Institut in Copenhagen, enrolled 103 hog workers in North Carolina and 80 members of their households (either children or other adults) to have their noses swabbed to determine whether they were carrying strains of S. aureus in their nasal passages. Each person was also shown pictures of skin and soft tissue infections caused by S. aureus and asked if they had developed those symptoms in the previous three months.

The researchers found that 45 of 103 hog workers (44 percent) and 31 of 80 household members (39 percent) carried S. aureus in their noses. Nearly half of the S. aureus strains being carried by hog workers were mutidrug-resistant and nearly a third of S. aureus strains being carried by household members were. Six percent of the hog workers and 11 percent of the children who lived with them reported a recent skin and soft tissue infection (no adult household members reported such infections).

Those hog workers who carried livestock-associated S. aureus in their noses were five times as likely to have reported a recent skin or soft tissue infection as those who didn't carry those bacteria in their noses. The association was stronger among hog workers who carried multidrug-resistant S. aureus in their noses, who were nearly nine times as likely to have reported a recent skin or soft tissue infection. Multidrug-resistant S. aureus infections can be difficult to treat because the antibiotic drugs that doctors typically prescribe don't work. Researchers are concerned about what might happen if these bacteria develop the capacity to spread more broadly between animals and humans.

While the study is small, Heaney says the findings suggest that more work is needed to figure out how to mitigate S. aureus exposure and the risk of infection among workers and to track the extent to which these livestock-associated bacteria may spread into the community at large. Since the study found that those hog workers who never wore protective masks over their nose and mouth were more likely to be carriers of the bacteria than those who did, Heaney says recommendations about wearing personal protective equipment might be prudent.

Heaney says 89 percent of the hog workers in the study were Hispanic and that many are likely without health insurance. Studies like this, he says, can help focus on risks to a population that is vulnerable and may otherwise fall through the cracks. According to a Duke University analysis of U.S. Bureau of Labor Statistics data, roughly 327,350 people were employed in hog farming in the United States in 2012.

Most evidence about the burden of human infections associated with drug-resistant S. aureus nasal colonization comes from studying strains that circulate in hospital settings, where patients are often tested upon admission so that medical staff can take precautions. Less is known about whether generally healthy people in the community, such as hog workers, are at increased risk of developing S. aureus infections.

The rise of multidrug-resistant bacteria - often called superbugs - is a global crisis according to the World Health Organization and the use of antibiotics in food animal production has been highlighted as an important contributor. Roughly 80 percent of antibiotics sold in the United States are used in animals, with heavy nontherapeutic uses in food animal production.

"This issue isn't going away and there are many more research questions that need to be answered," he says.
-end-
"Livestock-associated, antibiotic-resistant Staphylococcus aureus nasal carriage and recent skin and soft tissue infection among industrial hog operation workers" was written by Maya Nadimpalli, Jill R. Stewart, Elizabeth Pierce, Nora Pisanic, David C. Love, Devon Hall, Jesper Larsen, Karen C. Carroll, Tsigereda Tekle, Trish M. Perl and Christopher D. Heaney.

Funding for this study was provided by the National Institute for Occupational Safety and Health (1K01OH010193-01A1), the Johns Hopkins NIOSH Education and Research Center, the Johns Hopkins Center for a Livable Future, the Sherrilyn and Ken Fisher Center for Environmental Infectious Diseases Discovery Program at the Johns Hopkins University School of Medicine (018HEA2013), the National Science Foundation (1316318), the National Institute of Environmental Health Sciences (5T32ES007141-30), the Royster Society fellowship, an Environmental Protection Agency Science to Achieve Results fellowship the GRACE Communications Foundation and the National Institute for Allergy and Infectious Diseases (1R01AI101371-01A1).

Johns Hopkins University Bloomberg School of Public Health

Related Bacteria Articles from Brightsurf:

Siblings can also differ from one another in bacteria
A research team from the University of Tübingen and the German Center for Infection Research (DZIF) is investigating how pathogens influence the immune response of their host with genetic variation.

How bacteria fertilize soya
Soya and clover have their very own fertiliser factories in their roots, where bacteria manufacture ammonium, which is crucial for plant growth.

Bacteria might help other bacteria to tolerate antibiotics better
A new paper by the Dynamical Systems Biology lab at UPF shows that the response by bacteria to antibiotics may depend on other species of bacteria they live with, in such a way that some bacteria may make others more tolerant to antibiotics.

Two-faced bacteria
The gut microbiome, which is a collection of numerous beneficial bacteria species, is key to our overall well-being and good health.

Microcensus in bacteria
Bacillus subtilis can determine proportions of different groups within a mixed population.

Right beneath the skin we all have the same bacteria
In the dermis skin layer, the same bacteria are found across age and gender.

Bacteria must be 'stressed out' to divide
Bacterial cell division is controlled by both enzymatic activity and mechanical forces, which work together to control its timing and location, a new study from EPFL finds.

How bees live with bacteria
More than 90 percent of all bee species are not organized in colonies, but fight their way through life alone.

The bacteria building your baby
Australian researchers have laid to rest a longstanding controversy: is the womb sterile?

Hopping bacteria
Scientists have long known that key models of bacterial movement in real-world conditions are flawed.

Read More: Bacteria News and Bacteria Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.