Immunologic Predisposition of HIV Patients to Develop Methicillin-Resistant Staphylococcus Aureus (MRSA) Colonization and Infection

All participant inclusion criteria: * Greater or equal to 18 years of age * Willingness to undergo blood draw. Skin biopsy will be requested, but is optional -AND- HIV-positive and MRSA-negative Group: * Documented positive HIV test result * Negative colonization swabs for S. aureus within 14 days of enrollment * No evidence of skin/soft tissue infection HIV-positive and MRSA-Colonization Group: * Documented positive HIV test result * History of of colonization with MRSA w/in 14 days of study enrollment HIV-positive and MRSA Infection Group: * Documented positive HIV test result * Skin/soft tissue infection with a positive wound culture showing MRSA within 7 days of enrollment * MRSA infection is not associated with an intravenous catheter or other nosocomial procedure HIV Negative groups: * Same criteria used for the HIV-negative groups as listed above. * No history of HIV infection. * Willing to undergo an HIV blood test, which must have a negative result. Exclusion Criteria: * Women with positive urine pregnancy test within 7 days of study enrollment * Women who are within 6 months of being postpartum or who are currently breastfeeding * Subjects unable or unwilling to complete questionnaires and blood draw.