Syphilis Shows Some Resistance to Antibiotic in United States

A federal study released on Thursday found that syphilis may be developing resistance to one of the antibiotics used to treat it. San Francisco health officials documented eight cases in 2002 and 2003 in which single oral doses of azithromycin apparently did not cure the infection, according to a report published by CDC.

All the patients were gay males, five of whom had HIV. They were later successfully treated with either doxycycline or penicillin, the CDC's preferred antibiotic for treating syphilis.

Dr. Samuel Mitchell, a CDC epidemiologist and one of the authors of the study, said the San Francisco City Clinic has since dropped azithromycin for treating most cases of primary, secondary or early-latent syphilis. Azithromycin's apparent failure to cure syphilis is a disappointment to infectious disease specialists, who had hoped a single 1- or 2-gram oral dose would offer a more convenient, better treatment for many syphilis infections. It is easier to administer than benzathine penicillin, an antibiotic that is usually injected.

"The downside of azithromycin becoming less useful is that it will probably limit our ability to do in-the-field prophylactic treatment," said Mitchell. He urged doctors still prescribing the drug for syphilis to follow patients closely. Several studies have shown that azithromycin was effective in patients who did not have HIV.

The new study came out three days after CDC reported that the nation's syphilis rate appeared to have risen for the third consecutive year, mostly due to rising infections among gay and bisexual men. CDC estimated that 60 percent of cases last year occurred among men who have sex with men, compared to 5 percent in 1999.

Back to other news for March 12, 2004