2267. The Effect of Opportunistic Infection (OI) Prophylaxis on the Gastrointestinal Microbiome (GIM) and Immune Reconstitution (IR) in Veterans With HIV and AIDS

BACKGROUND: Despite antiretroviral therapy (ART), some patients do not achieve IR. Moreover, GI bacterial translocation may lead to a decrease in CD4 counts with an increase in IL-6 in blood. However, the effect of OI prophylaxis on the GIM, bacterial translocation and IR has not been studied in HIV+ veterans. Here we studied the gut microbiome and bacterial translocation in VA patients with (i) stable HIV on ART (controls), (ii) newly diagnosed HIV starting on ART (new dx) and OI prophylaxis, and (iii) resuming ART (resumers). METHODS: Blood and stool specimens from 16 controls, 4 new dx and 3 resumers were obtained at 3 visits, as well as clinical and virological data. PCR electrospray ionization mass spectrometry (ESI-MS) was performed on blood samples to detect bacteria. Quantitative cultures and gut microbiome (deep sequencing bacterial 16S rRNA) was done on stool. RESULTS: There was no relation between CD4 count, log CFU TMP-SMX-resistant Gram-negative bacteria (GNRs) or total anaerobes. Except for 2 control patients with a decrease in CD4 count <200, none took TMP-SMX. One of these control patients started TMP-SMX, while the other took atovaquone. Neither had TMP-SMX R GNRs in stool, despite low CD4 /TMP-SMX. Major stool phyla in controls were Bacteroidetes (37 ± 19%), Firmicutes (37 ± 14%), Proteobacteria (15 ± 14%); while resumers had 54 ± 15% Bacteroidetes, 33 ± 12% Firmicutes and 7 ± 1% Proteobacteria. Only one new dx individual had CD4 count <200 at dx and took doxycycline initially for hidradenitis supparativa. Dapsone was initiated due to sulfa allergy. He was also diagnosed with lung cancer, treated with resection/XRT and received cefazolin. His VL became undetectable but CD4 <200. He had persistence of TMP-SMX-resistant GNRs despite dapsone and a shift in his GIM was observed over the first 6 months of care, i.e., Bacteroidetes decreased from 61.5% to 29.5% and Firmicutes increased from 30.6% to 53.3%. CONCLUSION: OI prophylaxis does not affect the GIM of stable HIV VA patients on ART. TMP-SMX-resistant GNRs in stool are unrelated to TMP-SMX exposure or CD4 count. Other antibiotics such as doxycycline can alter GI microbiota and may affect immune reconstitution. DISCLOSURES: All authors: No reported disclosures.