A5286 is a randomized, open-label, two-arm, pilot (phase II) study that evaluated whether 4 weeks of treatment with rifaximin, a non-absorbable antibiotic, decreases markers of immune activation and levels of translocated gut microbial products in HIV-1 infected subjects virally suppressed on ART with CD4+ T-cells < 350 cells/mm^3. Rifaximin were admistered to subjects for 3 weeks. Follow-up continued to week 12. The total sample size was 73 subjects. Subjects were randomized at a 2:1 ratio (rifaximin: no study treatment), using permuted blocks, without institutional balancing.