The bacteria’s been around for a long time, but drug resistance is new.

Researchers at the University of Washington have identified a worrisome new bacterial cluster that’s growing in prevalence among men who have sex with men and is resistant to antibiotics.

The drug-resistant strains were identified in Seattle and Montreal, although researchers believe they’re common worldwide. Known as Campylobacter coli, the bacteria cause severe abdominal pain, bloody diarrhea, and fever and are estimated to affect about 1.3 million people in the United States annually. The journal Clinical Infectious Disease published the finding this month.

While the infection usually passes after a few days, it can pose a more serious threat to those with compromised immune systems.

Men who have sex with men are more prone to infection due to sexual practices like anal sex and rimming, according to the researchers. Transmission occurs when fecal matter enters another person’s body, and while it isn’t limited to any one population, gay men are more likely to experience drug-resistant infections because they’re more likely to have recieved antibiotics for similar infections in the past.

“The international spread of related isolates among MSM populations has been shown before for Shigella [another enteric pathogen], so it makes sense to see it in Campylobacter as well,” wrote the study’s lead author, Dr. Alex Greninger. “The global emergence of multidrug-resistant enteric pathogens in MSM poses an urgent public health challenge that may require new approaches for surveillance and prevention.”

The team of researchers suspects that the drug resistance emerged when bacteria were infected with viruses carrying drug-resistant genes in DNA sequences known as CRISPR (not to be confused with the gene-editing technology of the same name). This is the first time that antibiotic resistance is known to have been acquired in clinical samples through CRISPR.

Cases of Campylobacter enteritis are generally treated with antibiotics called macrolides and fluoroquinolones. Another drug known as fosfomycin may be an effective alternative. But emerging strains are showing resistance to all of those treatment options.

Health researchers have noted that sexually-transmitted infections are on the rise, but there’s less available data about the subset of enteric bacteria that includes Campylobacter. Unlike other infections, Campylobacter isn’t routinely monitored.

The University of Washington team has called for more robust surveillance methods to track infections, particularly in light of emerging drug resistance.

As always, the key to avoiding the transmission of Campylobacter and other STIs is frequent testing, open communication about sexual health with partners, and education about harm-reduction techniques.

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