A new, highly drug-resistant strain of the “flesh-eating” MRSA bacteria
is being spread among gay men in San Francisco and Boston, researchers
reported on Monday.


In a study
published online by the journal Annals of Internal Medicine, the
bacteria seemed to be spread most easily through anal intercourse but
also through casual skin-to-skin contact and touching contaminated

The authors warned that unless microbiology laboratories were able to identify the strain and doctors prescribed the proper antibiotic therapy, the infection could soon spread among other groups and become a wider threat.

new strain seems to have “spread rapidly” in gay populations in San
Francisco and Boston, the researchers wrote, and “has the potential for
rapid, nationwide dissemination” among gay men.

The study was
based on a review of medical records from outpatient clinics in San
Francisco and Boston and nine medical centers in San Francisco.

The Castro district in San Francisco has the highest number of gay
residents in the country, according to the University of California,
San Francisco. One in 588 residents is infected with the new
multidrug-resistant MRSA strain, the study found. That compares with 1
in 3,800 people in San Francisco, according to statistical analyses
based on ZIP codes.

A separate part of the study found that gay
men in San Francisco were about 13 times more likely to be infected
than other people in the city.

The San Francisco researchers
suggested that scrubbing with soap and water might be the most
effective way to stop skin-to-skin transmission, particularly after
sexual activities.

MRSA, for methicillin-resistant Staphylococcus aureus, was once spread chiefly in hospitals. But in recent years, a number of healthy people have acquired it outside hospitals.

Nearly 19,000 people died in the United States from MRSA infections in 2005, the Centers for Disease Control and Prevention has reported.

The infection can cause unusually severe problems, including abscesses and skin ulcers. The bacteria can invade through the skin to produce necrotizing fasciitis, giving them the popular name of flesh-eating bacteria. They can also cause pneumonia, damage the heart and produce widespread infection through the blood.

Among gay men in the study, MRSA was spread by skin contact, causing abscesses and infection in the buttocks and genital area.

The new strain is closely related to earlier ones. Both are known as MRSA USA300.

The strain is much more difficult to treat because it is resistant not
just to methicillin, but also many more of the antibiotics used to
treat the earlier strains, said Dr. Henry F. Chambers, an author of the
new study.


The new strain contains a plasmid called pUSA03.

“This particular clone is resistant to at least three other drugs,
clindamycin, tetracycline and mupirocin,” Dr. Chambers said in a
telephone interview.

Of the alternatives recommended by the
C.D.C. and the Infectious Diseases Society of America,
trimethoprim-sulfamethoxazole (Bactrim), clindamycin and a
tetracycline, “this strain is resistant to two of those three,” he
added. “In addition, the new strain is resistant to mupirocin, which
has been advocated for eradicating the strain from carriers.”

Via NY Times