Drug-Resistant MRSA Strain Spreading Through MSM Communities
Methicillin-Resistant Staphylococcus Aureus
Adrug-resistant strain of methicillin-resistant staphylococcus aureus, or MRSA,is appearing among men who have sex with men in Boston and San Francisco,according to a study published online in the journal Annals of InternalMedicine, the New York Times reports (Altman, New York Times,1/15). HIV-positive people "seem especially prone" to the infection,according to the San Francisco Chronicle (Russell, San FranciscoChronicle, 1/15).
For the study, Binh Diep, a researcher at the University of California San Francisco, and colleagues reviewed the charts of 183people treated for MRSA at the San FranciscoGeneral Hospital's Positive Health Program, an outpatient program for HIV-positive people. They also reviewed thecharts of an additional 130 people at Fenway Community Health clinic in Boston. The review found that MSM ages 18 to35 were the most likely to have the infection (Chase, Wall Street Journal,1/15). According to a statistical analysis based on ZIP codes, one in 588people in San Francisco's Castro neighborhood, which has the highest number ofMSM residents nationwide, is living with MRSA, compared with one in 3,800people across San Francisco. The study also found that MSM in San Francisco were 13 times more likely thanother city residents to contract MRSA (New York Times, 1/15).
The study found MRSA spreads most often through anal intercourse but also canbe spread through casual skin-to-skin contact or by touching contaminatedsurfaces. MRSA can cause abscesses and skin ulcers and can produce necrotizingfacsiitis, or flesh-eating bacteria. The infection also can cause pneumonia,heart damage and blood infections. Among MSM in the study, MRSA was spreadthrough skin-to-skin contact and caused abscesses and infection in the buttocksand genitals. The most effective way to prevent skin-to-skin transmission ofMRSA is to wash with soap and water, particularly after sex, the researcherssaid (New York Times, 1/15).
According to the Chronicle, the strain, called USA300, isresistant to six major antibiotic classes (San Francisco Chronicle,1/15). USA300 is resistant to two of the three alternative MRSA treatmentsrecommended by CDC and the Infectious Diseases Society of America, the Times reports.The strain also is resistant to mupirocin, which has been "advocated foreradicating the strain from carriers," Henry Chambers, a study author andchief of infectious diseases at SFGH, said (New York Times, 1/15).
USA300 is "more virulent than standard staph," Shelly Gordon, aninfectious disease specialist at CaliforniaPacific Medical Center, said. She added that emergency department physicians should test fordrug resistance to avoid using the wrong antibiotic and fueling furtherresistance (Wall Street Journal, 1/15). Diep added that"once" the strain "reaches the general population, it will betruly unstoppable. That's why we're trying to spread the message ofprevention."
According to the researchers, the increase in MRSA among MSM comes at a timewhen HIV, syphilis and rectal gonorrhea also are increasing in the populationin part because of an increase in risky sexual behavior and injection drug use.The "likelihood of contracting each of these diseases increases with thenumber of sexual partners that you have," Diep said, adding that the"same can probably be said for MRSA" (Beck, Reuters, 1/14). Chambers said that high antibiotic useis the "most important factor" that the new drug-resistant strain isappearing among MSM (Wall Street Journal, 1/15).
According to Francoise Perdreau-Remington -- director of the molecularepidemiology lab at SFGH, where the strain was first identified -- USA300 hasbeen found in 44 states and is beginning to spread through Europe.In 2007, CDC calculated that about 19,000 U.S. residents -- more than thenumber of people who die annually from AIDS-related causes -- died fromdrug-resistant strains of MRSA (San Francisco Chronicle, 1/15).
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