Possible MRSA link to gay sex seen

Gay male sex may be a risk factor for drug-resistant infections, according to studies based on medical records from health clinics in San Francisco and Boston.

Infections caused by methicillin-resistant Staphylococcus aureus, or MRSA, that were seen in gay men frequently appeared on parts of the body in contact during sex, according to research conducted at Boston's Fenway Community Health Clinic and San Francisco General Hospital's HIV clinic. Researchers also found that sexually active gay men in San Francisco were 13 times more likely to be infected with MRSA than the general population.

The study did not investigate the cause of the increased risk, although researchers said they suspected that gay men may be more vulnerable to drug-resistant germs because of wider use of antibiotics and riskier sexual behaviors. HIV-positive patients are most likely to take antibiotics, and such frequent use means that the most resistant bacteria survive, according to lead study author Binh Diep.

"The study shows HIV-positive men have a higher rate of antibiotic use," Diep, of the University of California in San Francisco, said in a telephone interview. "Then from there it spreads into other men who have sex with men, who don't necessarily use the antibiotics. From there, through casual contact or contaminated surfaces, it can spread far and wide."

Diep helped map the genome of a strain of MRSA known as USA300. The research on gay men was published yesterday in the online edition of Annals of Internal Medicine.

The Centers for Disease Control and Prevention, which does not require states to report MRSA cases, estimates that 94,360 invasive MRSA infections occurred in the United States in 2005 and that those infections were associated with 18,650 deaths. Researchers estimate that the germs sicken two million people annually and cost about $20 billion to treat nationwide.

MRSA can cause diseases such as pneumonia, blood infections, and necrotizing fasciitis, the so-called flesh-eating bacteria. The majority of the cases Diep studied were not life-threatening, he said.

"A good shower with soap and water would be an effective way to prevent acquisition of the bug if you come into contact with other people who are carriers or infected," Diep said.