HIV epidemics started with a boom in the gay communities. Now, the same category seems to be a hotbed for a new, highly antibiotic-resistant strain of superbug or MRSA (methicillin-resistant Staphylococcus aureus) bacteria, as found by an UCSF study published in the "Annals of Internal Medicine." Like HIV, the new bacterium can be transmitted most easily through sex, but it also can be caught through casual skin-to-skin contact or by touching contaminated surfaces and that's why researchers are worried it could trigger an epidemic among the general population.

The new bacterium is a strain of MRSA bacterium that has caused in the last years outbreaks of severe infections of the skin and other organs in hospitals and beyond. The new MRSA USA300 is resistant to many front-line antibiotics and it invades the skin and tissue beneath, provoking abscesses and ulcerations capable of evolving quickly into life-threatening infections.

"These multi-drug resistant infections often affect gay men at body sites in which skin-to-skin contact occurs during sexual activities. But because the bacteria can be spread by more casual contact, we are also very concerned about a potential spread of this strain into the general population. A good scrubbing with soap and water may be the most effective way to prevent skin-to-skin contact transmission, especially after sexual activities, " said lead author Dr. Binh Diep, UCSF postdoctoral scientist at San Francisco General Hospital Medical Center.

The research used data of medical records from outpatient clinics in Boston and 9 San Francisco medical centers.

"About one in 588 people living in San Francisco's Castro district - a neighborhood with the highest number of gay residents in the country - are infected with the multi-drug resistant MRSA bacteria. About one in 3800 San Franciscans overall are infected - also a surprisingly high number. These statistics come from the scientists' study of MRSA samples previously collected from patients in nine medical centers serving San Francisco," Diep said.

The research revealed that sexually active gay men in San Francisco were 13 times more vulnerable to catch the infection than the overall population.

"The potential widespread dissemination of multi-resistant form of USA300 into the general population is alarming," Diep added.

MRSA bacteria have been confined to hospitals till recently, being a result of over use of antibiotics, but in 2006, the bacteria were first reported in communities by an UCSF team.