Gonorrhea is on the rise — and not only that, but cases of a strain of drug-resistant gonorrhea have more than quadrupled in the United States between 2013 and 2014, according to new data from the U.S. Centers for Disease Control and Prevention The report, released on Thursday, warns that gonorrhea is growing even more resistant to antibiotic treatment, and that the only two drugs left that treat the disease may become useless. The news comes soon after England's chief medical officer also warned in January that gonorrhea may become untreatable.Robert Kirkcaldy, MD, the author of the CDC's report, seems to agree. “The potential for untreatable gonorrhea is a very real possibility in the future,” he told STAT News . "What we do know is that this bacteria has demonstrated the ability, repeatedly, to develop antibiotic resistance to the drugs that have been used for it."The CDC recommends doctors continue to use a combination of two drugs, an injection of ceftriaxone and an oral course of azithromycin, to treat the STI. As of now, the rate of resistance remains relatively low. Of the samples that the CDC tested, 0.6% were resistant to azithromycin in 2013, rising to 2.5% in 2014. For ceftriaxone, the rate doubled, from 0.4% in 2013 to to 0.8% in 2014. Dr. Kirkcaldy explained to STAT that gonorrhea has already become resistant to multiple classes of other antibiotics, so any rise in resistance is worrisome.