For several years, public health officials have been concerned that gonorrhea, one of the most prevalent STDs in the world, might become resistant to the last widely available antibiotics used to treat it, a class of drugs called cephalosporins.
Now, it has.
In the space of one week, infectious disease specialists have received a one-two punch of bad news that confirms those fears, including the discovery of a new, cephalosporin-resistant strain of the bacteria.
The percentage of U.S. gonorrhea cases that are less susceptible to the two cephalosporins used to treat it, cefixime, taken orally, and ceftriaxone, injected, is on the rise, according to the Centers for Disease Control and Prevention's latest Morbidity and Mortality Weekly Report
The Gonococcal Isolate Surveillance Project, a lookout program designed to spot resistance, found that 1.4 percent of patient samples showed growing ability to defeat cefixime in 2010 compared to just .2 percent in 2000. Resistance to ceftiaxone grew from .1 percent to .3 percent during the same period.
Then Sunday, a Japanese-European team presenting data at the International Society for Sexually Transmitted Disease Research meeting in Quebec City, Canada, publicly announced the discovery of a new strain of gonorrhea, H041, that displays a strong resistance to ceftriaxone.
"This is both an alarming and a predictable discovery," said one of the project's lead researchers, Dr. Magnus Unemo of the Swedish Reference Laboratory for Pathogenic Neisseria.
H041, first found in a the pharynx of a Japanese sex worker, is 4- to 8-fold more resistant to ceftriaxone — the only form of cephalosporin used to treat that type of gonorrhea in the throat — than any strain ever found.
Resistant strain could arrive in U.S. soon
When researchers grew H041 with other gonorrhea strains, genetic recombination increased those strains’ resistance by up to 500-fold.
“Why this is so concerning is that there are no other treatment options besides cephalosporins right now,” said Dr. Kimberly Workowski, an STD infection expert at Emory University. “For pharyngeal infection, oral drugs do not work and ceftiaxone is the only injectable.”
What’s more, she explained, if history is any guide, the H041 strain will soon arrive in the U.S.
Workowski and other experts stressed that it’s too soon to panic. By increasing dosages —though at greater risk of toxic side effects — and combining the cephalosporins with azithromycin or doxycycline, both strategies the CDC began recommending last year, the vast majority of gonorrhea cases will be effectively treated for now.
But, said Dr. Edward Hook, professor of medicine at the University of Alabama at Birmingham, experts face a serious and growing problem that will be debated.
"Could we be developing a problem that is far worse and more problematic? Absolutely," said, Hook, an author of the MMWR report. "It is something that needs to be attended to not just for gonorrhea but for other” bacterial infections for which antibiotic resistance is growing.