Scientists studying superbugs are reaching deep for data. Specifically in, ahem, surfer’s rectums.

The antibiotic-resistant bacteria, which constitute one of the greatest health threats to humans today, are lurking in our oceans, largely owing to improper sewage disposal and other pollution. Scientists who study antibiotic resistance needed to find a sample of people who were frequently exposed to the polluted water. The answer was simple: surfers, who swallow an estimated ten times more water than the average beachgoer. Unfortunately for the surfers, superbugs are best studied in the gut — which is most easily reached via a rectal swab.

“We’ve already shown that this water may contain antibiotic resistant bacteria, but we have no idea how this might affect the microbes that live in our guts, or how it could impact upon health,” said research Anne Leonard of the University of Exeter Medical School, who is leading the aptly named Beach Bums study. She’s teamed up with the charity Surfers Against Sewage, which campaigns to protect U.K. oceans and beaches, to recruit at least 150 surfers and body boarders for the study. They’re also asking the surfers to bring friends who don’t surf, as a control group. 

The World Health Organization considers antimicrobial resistance a serious threat to global public health. A 2014 report states: “A post-antibiotic era — in which common infections and minor injuries can kill — far from being an apocalyptic fantasy, is instead a very real possibility for the 21st century.” Bacteria, parasites, viruses, and fungi are increasingly showing resistance to drugs. The WHO has already confirmed that the drug of last resort for the STI gonorrhea, caused by a bacterial infection, is failing in several countries. Urinary tract infections caused by the common bacteria E. coli are also becoming increasingly untreatable, as are the severe infections caused by Staphylococcus aureus, a bacteria often found throughout healthcare facilities. Multidrug-resistant tuberculosis is also becoming a serious threat, requiring much longer treatment time and more extensive resources to treat.

Multidrug resistance isn’t going to be easy to contain. Doing so will require the concerted effort of multiple nations in regulating the use of broadly used antibiotics in animal farming, ensuring populations are properly vaccinated, and ensuring antibiotics are only prescribed and used when absolutely necessary. U.K. surfer’s backsides are but one front in that battle.