Drug-resistant germs from livestock—born from overuse and misuse of antibiotics—can make their way off farms and into unsuspecting people, where they can cause difficult-to-treat infections. But following their path from farms to people is tricky. After decades of spats with public health and animal rights advocates, farm owners are not eager to share information on their antibiotic practices or the superbugs that may lurk on their farms.

Researchers caught in the middle have been left to find workarounds, collecting bits and pieces of data to try to retrace the steps of superbugs as they migrate off farms. A new study, published in the April issue of Environmental Health Perspectives, offers some new, snotty clues about their path.

In the study, children of pig farm workers were more than twice as likely to have their noses stuffed with drug-resistant germs than other kids, researchers report. Perhaps more surprisingly, the nose-dwelling germs found in kids didn’t tend to match their parents’ snotty superbugs. This suggests that superbugs may travel to kids more readily on clothes and equipment than through person-to-person contact—or at least adult-to-kid contact.

The researchers also noted that other families in the community who had no direct connection to farms seemed to get superbugs, genetically linked to farms, up in their snouts.

Overall, the data hints at the idea that the sticky fingers of booger-mining kids could be important spreaders of drug-resistant germs—they may pick up farm-borne pathogens readily from their environment and pass them around. It also points to the possibility that a main vehicle for farm exodus of superbugs is through dust and mud that can spread into the community via contaminated clothes, boots, and wind. Unfortunately, far more data needs to be collected to definitively know how they fit into the transmission of drug-resistant bacteria moving off farms.

Scary snot

In the study, led by researchers at Johns Hopkins and the University of North Carolina, Chapel Hill, researchers recruited one adult and one child from each of 400 households in areas of North Carolina where there’s intense pig farming. The researchers swabbed the noses of 198 hog farm workers and one of their children, younger than seven. For comparison, the researchers also swirled the noses of 202 non-farm workers in the same communities, as well as one of their kids.

Among the adults, there weren’t significant differences in rates of carrying methicillin-resistant Staphylococcus aureus (MRSA) or multi-drug resistant S. aureus (MDRSA). About 2 percent of adults who worked in pig farms had MRSA in their noses, while about 3 percent of community members were carriers. For MDRSA, about 12 percent of farm workers tested positive, while 8 percent of community members did.

It was a different story for the kids. About 14 percent of the hog farmers' kids had MRSA in their noses, and 23 percent carried MDRSA. The carriage rates of other kids in the community were 6 and 8, respectively.

The researchers didn’t find a strong connection between the hog farmers' nasal inhabitants and those of their kids. But there was a strong link between the presence of schnoz Staph in kids and if their hog farming parents brought their protective equipment home.

The study offers interesting pieces of data to try to piece together superbugs' route. But there’s a lot of data still missing. In this case, the authors of the study were unable to sample the germs in pig farms to confirm their origins. They also couldn’t collect data on antibiotic use on the pig farms.

Overall, "further studies should be conducted to determine whether the MRSA and MDRSA nasal carriage prevalence in children in [hog farm] worker households in the United States represents a risk factor for infection,” the authors conclude.

Environmental Health Perspectives, 2017. DOI: 10.1289/EHP35 (About DOIs).