Tenacious STD: drug-resistant gonorrhea is spreading

Science News, April 21, 2007 by Brian Vastag

Responding to a surge in tough-to-treat gonorrhea, the Centers for Disease Control and Prevention has stopped recommending a group of related antibiotics for the disease. Now, only one class of antibiotic--called cephalosporins--remains on the CDC's list of treatments for the second-most-common sexually transmitted disease in the United States.

"This is a bad bugs-no drugs issue," says Henry Masur, president of the Alexandria, Va.-based Infectious Diseases Society of America.

An estimated 1.4 million people in the United States contract gonorrhea each year, according to Masur's group. Left untreated, the disease can cause infertility in both men and women and can spread to the blood or joints where, in rare cases, it's fatal.

When the powerful antibiotic ciprofloxacin (Cipro) and its relatives were initially used, a single dose generally wiped out the infection. But in the 1990s, the CDC noted the emergence in Asia of ciprofloxacin-resistant gonorrhea.

This strain spread to men and women in Hawaii and California and to men elsewhere having homosexual encounters. By 2004, the CDC had stopped recommending ciprofloxacin treatment for these groups.

The bug continued spreading, and new data show that about 13 percent of gonorrhea infections across the United States are resistant to ciprofloxacin and the other fluoroquinolones.

"It isn't surprising, unfortunately," says Eileen Yee, an epidemiologist at the CDC in Atlanta. "It makes controlling [the spread of] gonorrhea difficult."

According to the CDC data, collected from sexually transmitted disease clinics, 7 percent of infections among heterosexual males are resistant. Among men who have sex with men, that figure is 38 percent. Women are not included in any of the new data, reported in the April 13 Morbidity and Mortality Weekly Report, which the CDC publishes.

In contrast to those data, ciprofloxacin resistance in 2001 showed up in less than 1 percent of gonorrhea infections in heterosexual men and in fewer than 2 percent of infections in men who have sex with men.

The CDC now lists just one recommended treatment for gonorrhea: injected or oral cephalosporin-class drugs. However, only an injected formulation is available for adults in the United States.

Masur joins the CDC in calling for drug companies to accelerate development of new antibiotics. But because antibiotics work in just one dose or a few doses, they're generally less profitable than drugs that patients take for months or years.

"The problem is that unless somebody guarantees them a market, no drug company wants to make a one-pill [treatment]," Masur says. "We need to find incentives for small companies or generic [manufacturers] to make this kind of drug."

A bill now in Congress would provide incentives for the research and manufacture of new antibiotics.