Dr. Vanessa Allen of Public Health Ontario and colleagues identified 291 patients at the clinic who tested positive for gonorrhea between May 2010 and April 2011. The Canadian patients whose gonorrhea was resistant to cephalosporin — the most commonly used antibiotic for gonorrhea — were eventually cured by a powerful injectable antibiotic, ceftriaxone. But experts fear even that drug has its limits, since doctors are seeing a rise in resistance to ceftriaxone, too.

“The next threat is when, not if, the same thing happens with ceftriaxone. And then what?” lead researcher Allen told US News. “I think without a doubt this will become a bigger problem.”