A new study has found that a drug-resistant strain of methicillin-resistant staphylococcus aureus (MRSA) is appearing among men who have sex with men (MSM) in Boston and San Francisco.  The strain, called USA300, is resistant to six major antibiotic classes and is resistant to two of the three alternative MRSA treatments recommended by CDC and the Infectious Diseases Society of America.  MRSA can cause abscesses and skin ulcers and can produce necrotizing facsiitis, or flesh-eating bacteria.  The infection also can cause pneumonia, heart damage, and blood infections.  

In the study population, MRSA spread most often through anal sex but also was spread through casual skin-to-skin contact or touching contaminated surfaces.  Among the men in this study, MRSA was spread through skin-to-skin contact and caused abscesses and infection in the buttocks and genitals or perineum.  The study authors note that the same risk behaviors that are of concern for recent increases in HIV infection and syphilis are also association with the spread of USA 300.  These are the use of crystal meth (methamphetamine) and other drugs, sex with multiple partners, participation in a group sex party, internet initiated sexual contacts, sexual activities that cause skin abrasions, and history of STDs.  Men who travel to San Francisco and engage in these higher risk sexual activities may also be at risk, since there have been many cases of USA300 diagnosed among MSM in that city.