Eligibility Criteria:
Inclusion Criteria:
1. Age \> 18 years
2. HIV infection as reported by the subject's physician
3. Physician-reported SSSI within the prior 6 months.
4. S. aureus colonization at ≥ 1 body site as defined as a positive culture for S. aureus at minimum one of five cultures taken at pre-enrollment screening.
5. Subjects (or their legally acceptable representatives) must have signed an informed consent documentation indicating that they understand the purpose of and procedures required for the study, and are willing to participate in the study
Exclusion Criteria:
1. Female subjects who are pregnant or lactating.
2. Known or suspected hypersensitivity to rifabutin, a rifamycin class antimicrobial, TMP-SMX or another sulfa based medication.
3. Known or suspected condition or concurrent treatment that would be contraindicated by the prescribing of rifabutin or TMP-SMX.
4. Receipt of an anti-staphylococcal antimicrobial within 14 days prior to administration of study drug (TMP-SMX, clindamycin, any macrolide, any tetracycline, any rifamycin, any fluoroquinolone, vancomycin, linezolid, daptomycin, any penicillin, any carbapenem, or any cephalosporin).
5. Diagnosis of an active SSSI or other signs and symptoms of S. aureus infection at the time of study enrollment
6. Physician-reported diagnosis of active or untreated latent mycobacterial infection
7. CrCl \< 30 ml/min as determined by the Cockcroft-Gault Method using a serum creatinine from a value obtained within the last 6 months.
8. No serum creatinine value available for the subject in the SFGH clinical laboratory system (LCR) within 6 months prior to enrollment.
9. Physician-reported diagnosis of end-stage liver disease
10. Physician-reported diagnosis of uveitis in the past or at time of enrollment
11. Concomitant use of medications with unknown pharmacokinetic interactions with rifabutin or contraindicated with rifabutin (unboosted indinavir, unboosted saquinavir, delavirdine, atovaquone, azithromycin, Bacillus of Calmette and Guerin \[only if recent administration for bladder cancer treatment\], dapsone, dasatinib, erlotininb, ethinyl estradiol, fluconazole, imatinab, itinotecan, itraconazole, ixabepilone, lapatinib, levonorgestrel, mestranol, nilotininb, norelgestromin, norethindrone, posaconazole, ranolazine, sirolimus, sunitinib, tacrolimus, temsirolimus, trimetrexate, voriconazole, warfarin)
12. Colonizing S. aureus isolate resistant to TMP-SMX
13. Colonizing S. aureus isolate resistant to rifampin (rifampin resistance will serve as a surrogate for rifabutin resistance at initial screening)
14. Subjects who are unlikely to be able to comply with the mandated study visits