DESIGN: This single center, double-blinded, randomized phase II study is being conducted to assess the efficacy of a rifabutin based regimen to eliminate S. aureus colonization in HIV infected individuals. Individuals must have HIV infection and a skin and skin structure infection (SSSI) in the prior 6 months to be eligible for screening. Prior to enrollment, subjects will be cultured for evidence of S. aureus colonization. Individuals who are culture positive at ≥ one body site will be eligible for enrollment. Subjects who meet inclusion and exclusion criteria and consent to participate in the study will be randomized to seven days of rifabutin plus trimethoprim-sulfamethoxazole (TMP-SMX) or TMP-SMX alone. Following completion of treatment subjects will be screened seven days, 30 days, and 60 days post-treatment for colonization at multiple body-sites. Subjects will also be actively followed for evidence of SSSI.

SUBJECT PARTICIPATION DURATION: 12 weeks

SAMPLE SIZE: 88 total subjects

POPULATION: 200 HIV infected individuals who receive care at San Francisco General Hospital HIV clinic (Ward 86) with a history of SSSI in the prior 6 months will be screened for S. aureus colonization.

DESCRIPTION OF AGENT OR INTERVENTION: This is a double-blind trial comparing rifabutin plus TMP-SMX versus placebo plus TMP-SMX. Placebo will be administered at a dose of 300 mg p.o. daily or an equivalent dose depending on co-administration of other drugs that may adjust the serum level of rifabutin. TMP-SMX will be administered at a dose of trimethoprim 160 mg and sulfamethoxazole 800 mg p.o. twice daily or adjusted per CrCl. Study drug will be provided by the study and administered for 7 days.