SHIFT: Studying HIV Immunology After Fecal Transplant

Inclusion Criteria: 1. Men and women ages 18 - 75 years. 2. HIV-1 positive: 3. Ability and willingness of participant or legal guardian/representative to provide informed consent. Exclusion Criteria: 1. Patients with a history of significant allergy to tree nuts, peanuts, shellfish, and/or eggs, vancomycin, levofloxacin, or metronidazole, chocolate/cocoa or gelatin; or unwillingness to ingest gelatin (in placebo capsules) 2. Use of investigational therapies or investigational vaccines within 90 days prior to study entry 3. Serious illness requiring systemic treatment and/or hospitalization within 30 days prior to entry 4. History of positive HCV antibody with detectable HCV RNA in plasma within 48 weeks prior to study entry. 5. History of positive HBsAg within 48 weeks prior to study entry 6. Liver cirrhosis, history of C. difficile infection, history of inflammatory bowel disease, bariatric surgery, total colectomy, colon or rectal anastomosis, bowel resection, or current colostomy. 7. Current diagnosis of diabetes 8. BMI \>35 9. Either breastfeeding or pregnant within 24 weeks prior to study entry 10. Tendinopathy or peripheral neuropathy (potentially exacerbated by antibiotic pretreatment) 11. Use of immunosuppressives, immune modulators, or antineoplastic agents for more than 3 consecutive days within the 60 days prior to study entry. 12. Use of probiotics and prebiotics (supplements and products) within 30 days of the study. Yogurt with live cultures is allowed. 13. Diagnosed bacterial enteric infection within 30 days prior to study entry. 14. Acute diarrhea within 30 days of study entry. 15. Weight loss or gain of more than 25 pounds in the 24 weeks prior to study entry.