Gonorrhea is becoming more difficult to treat with readily available antibiotics. In time, a case may show up in the U.S. that doesn't respond to any drugs currently in use.
Last week, the world's first case of drug-resistant gonorrhea -- in a sex worker in Japan -- was reported during a conference on sexually transmitted disease research. Earlier this month, the U.S. Centers for Disease Control and Prevention reported increased rates of gonorrhea cases that, while not quite resistant to antibiotics, are requiring larger doses to treat effectively.
Gonorrhea is still relatively easy to cure, and the United States hasn't yet had a patient who wasn't successfully treated with antibiotics. But a strain of gonorrhea unresponsive to current treatments likely will begin circulating worldwide at some point.
"We're not seeing any untreatable cases in the United States, but we're seeing proof that what we've been worrying about for a while has actually happened" in Japan, said Dr. Susan Philip, the San Francisco Public Health Department's director of STD prevention. "If previous patterns hold true, drug resistance should slowly move its way toward us."
Gonorrhea is the second most common sexually transmitted infection after Chlamydia. The bacterium typically infects the male and female reproductive tracts, the rectum or the mouth. Symptoms can include a burning sensation when urinating and a discharge from the penis or vagina. But half of women, and a small percentage of men, have no symptoms. If the infection is in the rectum or mouth, most people won't know it.
Untreated gonorrhea can cause pelvic inflammatory disease and infertility in women. People infected with gonorrhea are more susceptible to contracting HIV.
For decades, gonorrhea was treated with penicillin but, like many other bacteria, gonorrhea mutates quickly and often. Eventually, strains that didn't respond to penicillin circulated widely around the world.
By the 1980s, penicillin had been replaced with a class of antibiotics known as fluoroquinolones to treat gonorrhea. But eventually those stopped working, too. In 2007, the CDC changed its guidelines and recommended treatment with yet another class of antibiotics, called cephalosporin.
Now that antibiotic isn't working as well as it once did. Over the past decade, public health labs have found more cases that require higher doses of cephalosporin to kill the bacteria. Higher doses are usually the first sign that the bacteria is building resistance to a drug.
"We're down to our last class of antibiotics that we use to treat gonorrhea," said Dr. Heidi Bauer, chief of program development and evaluation in the California public health department's STD Control Branch.
California and Hawaii are usually the first spots in the country to see drug-resistant strains of infectious diseases because such cases typically come from Asia, where viral and bacterial infections may circulate more freely in crowded cities where there isn't good access to health care. Immigrants and tourists traveling west bring new strains with them -- to Hawaii and California, then the rest of the country, say epidemiologists.