‘Superbug’Worries About a Gonorrhea

Government heath officials are warning that gonorrhea, one of the most common sexually transmitted diseases, is becoming increasingly resistant to the last type of antibiotics left to treat it.

Although no cases of resistant gonorrhea have been reported in the United States, the Centers for Disease Control and Prevention says its own laboratory studies are detecting growing signs of resistance to a class of antibiotic drugs called cephalosporins. In addition, resistant strains already have shown up in other countries. Recently, two cases in which gonorrhea treatment failed were reported in Norway among heterosexual men, and a new resistant strain of the bacteria was identified from a female sex worker in Japan, a finding reported this week at the International Society for Sexually Transmitted Disease Research conference in Quebec.

The new strain may be “a true superbug that initiates a future era of untreatable gonorrhea,’’ wrote the team of Japanese and Swedish scientists in a recent report about the new strain.

In its Morbidity and Mortality Weekly Report, the C.D.C. reported last weekon a decade-long analysis of 5,400 to 6,500 annual gonorrhea cases from men treated in 30 American cities. From 2000 to 2010, the percentage of gonorrhea cases that showed potential resistance to two cephalosporin drugs rose sharply. Surveillance data from 2010 showed that over all, 1.4 percent of samples showed increasing resistance to the oral drug cefixime, up from 0.2 percent in 2000. Resistance to the injectable drug ceftriaxone rose to 3 percent, up from 1 percent a decade ago.

Some parts of the United States showed bigger increases than others. For instance, testing in Honolulu found 7.7 percent of 2010 samples with potential resistance to cefixime, compared with none in 2000. In California, 4.5 percent of samples showed signs of resistance in 2010, up from zero in 2000.

Health officials emphasized that while the signs of growing resistance are seen in laboratory studies, so far in the United States, there have been no cases of treatment-resistant gonorrhea in patients. The trends, however, are concerning, because cephalosporin drugs are the fourth type of antibiotic used to treat gonorrhea since the 1940s. Resistance to penicillin and tetracycline occurred during the 1970s and became widespread during the early 1980s, the C.D.C. reported. More recently, the disease became resistant to a class of antibiotics called fluoroquinolones, and in 2007 the government stopped recommending those drugs for gonorrhea treatment. That left cephalosporin drugs as the last line of defense against gonorrhea.

“The measurements we’re finding in the laboratory do show concerning trends of declining susceptibility to cephalosporin antibiotics,’’ said Dr. Robert D. Kirkcaldy, a medical epidemiologist in the C.D.C.’s division of sexually transmitted disease prevention and co-author of the agency’s report last week. “What we’ve been noticing is really since 2009 and 2010, it’s taking higher concentrations of antibiotic to kill the bacteria. This could mean resistance to the last antibiotic we have for gonorrhea could be on the horizon.’’

The problem of growing resistance appears limited to gonorrhea and is not occurring with other sexually transmitted bacterial diseases. “It’s a very complex bacteria which has a pretty amazing ability to mutate and for people to develop resistance to antibiotics,” said Dr. Kirkcaldy. “It has a pretty documented track record of developing resistance since the dawn of the antibiotic age.”

More than 700,000 people in the United States get gonorrhea every year, although about only half those cases are reported to public health agencies. In women, untreated gonorrhea can lead to fertility problems, pelvic inflammatory disease or ectopic pregnancy, and pregnant women can pass the disease to their babies. In men, the disease can cause painful scarring of the urethra, urination problems and kidney failure. Long-term complications for both sexes include joint pain, heart valve infection and meningitis.

The signs of emerging resistance to cephalosporin drugs are following roughly the same patterns that occurred when gonorrhea became resistant to fluoroquinolones a few years ago. In that case, resistance was documented first in Asia, then emerged in the United States, first in Hawaii followed by other Western states, according to the C.D.C.

The hope is that new antibiotics eventually can be developed to treat gonorrhea.

“The challenge is that there is not a well-studied second antibiotic we can turn to even when cephalosporin resistance does emerge,” said Dr. Kirkcaldy. “That’s why we’re so concerned, and one reason we wanted to sound the alarm about these findings. It’s incumbent on researchers in the pharmaceutical and other sectors to step up quickly and boldly to identify new drug combinations.”