People swabbed their own butts for this study.
Antibiotic-resistant bacteria transform easily curable infections into potentially fatal diseases. A new British study has zeroed in on an unlikely contributor to the spread of these superbugs: Surfers.
The researchers collected self-administered rectal swabs from 143 surfers and 130 non-surfers throughout England and Wales to identify the microbes in their colons. (The study was aptly named the Beach Bum Survey.) While only four non-surfers (3 percent) carried an antibiotic-resistant strain of Escherichia coli bacteria in their gut, 13 surfers (9 percent) carried the same antibiotic-resistant bacteria.
“These are small numbers, but the differences between surfers and non-surfers is important,” says study author Anne Leonard, a research fellow at the University of Exeter. “Three times the number of surfers were colonized [with the bacteria] than non-surfers and that difference is statistically significant, so yes, it is a concern.”
The scientists were hunting for particularly dangerous bacteria that are not only resistant to several different types of antibiotics on their own, but can also pass that trait on to other nearby bacteria thanks to what’s known as mobile genes. These microbes produce an enzyme called extended spectrum beta-lactamase, which breaks down antibiotic compounds. Even the segments of DNA that produce these enzymes in resistant bacteria can be transferred to ordinary bacteria, the way you might share your Netflix password with a friend. The surfers were four times as likely as non-surfers to harbour resistant E. coli with mobile genes.
Antibiotic-resistant bacteria emerge when antibiotic drugs are administered improperly to people or livestock, allowing the rare bacterial strains that have natural defenses against antibiotics to multiply. The superbugs can be passed on any other way that infections spread, like through person-to-person contact or touching infected surfaces. But the antibiotic-resistant bacteria in coastal waters most likely find their way to the shore first by hitching a ride through digestive tracts in feces. Then that waste is washed out of livestock pastures or manure-using farms with rainwater, or it’s dumped with untreated human sewage into waterways that ultimately drain into the ocean.
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The unlucky surfers, thanks to the lengthy time they spend in the water and their inevitable wipeouts, swallow far more seawater than the average beachgoer—about 5.75 ounces of seawater every day they spend catching waves, according to a 2008 study at Oregon State University. Separate studies have found that swimmers consume just half an ounce of water in the ocean, while recreational divers take in about one third of an ounce; so surfers swallow at least 10 times more water. The surfers in the study also spent far more time at the beach, with nearly 75 percent of them making more than 20 trips to the beach in the previous six months, compared to just 3 percent of non-surfers.
Once the antibiotic-resistant E. coli is ingested, it can take up residence in the host’s colon. And the host might not even feel sick. “This might be due to the E. coli in their gut being harmless varieties,” Leonard says. “Another explanation could be that the surfers taking part in our study tended to be young, less than 45 years old, and their immune systems are strong and able to fight off infections effectively.” An Australian study found that in most cases, the body gets rid of an E. coli infection in a matter of months. Before then, however, the E. coli is still capable of spreading to another part of the body and causing an infection (urinary tract infections and meningitis are a particular risk) or passing their antibiotic resistance on to other bacteria.
Whether you’re a surfer or not, your individual risk of catching an antibiotic-resistant bug from poo-contaminated ocean water might sound slim. But based on the number of people who go to the beach and the amount of contaminated water along the UK coast, the study estimated that there could be 2.5 million incidents each year where someone jumped in the ocean and came out carrying at least one antibiotic resistant bacterium—and that’s just in England and Wales. “In regions with tropical climates and warmer waters, surfers might typically be exposed more frequently or for longer than the UK surfers participating in this study,” Leonard says.
The real risk is that those beachgoers who do get infected will wind up spreading those superbugs around, even if they don’t get sick themselves. “Higher rates of antibiotic-resistant bacteria carriage in the community puts vulnerable people at risk of acquiring resistant infection through person-to-person transmission,” Leonard says.
Despite that danger, you don’t need to pack up your surfboard for good. After all, the culprit is not people who enjoy sun and sand, but the overzealous use of antibiotics to begin with. Leonard suggests checking beach reports for water quality before you head to the shore. Most water pollution monitoring is handled by state or local agencies, with unfortunately little standardization between them, so use this list maintained by the Environmental Protection Agency to find the website and phone number for the organization responsible for your favorite sandy stretch of coast.
If your local agency closed a beach or issued other advisories related to E. coli or pollution (particularly after heavy storms, which tend to wash more waste out to sea), maybe plan an activity that keeps you out of the water.
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