Objective: Untreated advanced HIV infection alters the gut microbiota, but it is unclear whether antiretroviral therapy (ART) reverses these changes. We compared the composition of the rectal microbiota among three groups of men who have sex with men (MSM): HIV-uninfected, untreated HIV, and ART-treated HIV-infected.
Design: A cross-sectional study was conducted among 130 MSM (55 HIV-uninfected, 41 untreated HIV, and 34 ART-treated HIV) in Abuja, Nigeria.
Methods: Bacterial 16S rRNA genes were amplified from rectal swabs, sequenced and clustered into Genera-level operational taxonomic units. Alpha diversity was quantified using the Shannon index and compared among groups using the Kruskal-Wallis test; associations with other scale variables were quantified using Spearman's rank correlation (Rs). The relative abundance of the top 15 taxa was compared according to HIV infection/treatment status using the Wilcoxon rank sum test.
Results: HIV-treated MSM had a decrease in a commensal phylum, Bacteroidetes (P < 0.01). Alpha diversity was positively correlated with viral loads (Rs = 0.32, P < 0.01). Statistically significant shifts in relative abundance of rectal microbiota for the HIV-treated group included a decrease in the most abundant bacteria, Prevotella (P = 0.02) and an increase in pathogenic bacteria, Peptoniphilus (P = 0.04), Finegoldia (P = 0.01), Anaerococcus (P = 0.03), and Campylobacter (P = 0.03) compared with the other groups.
Conclusion: Untreated HIV infection does not significantly alter the rectal microbiota, whereas prior treatment is associated with a shift toward a more pathogenic pattern of microbiota. Treatment with an antibiotic, co-trimoxazole, in conjunction with ART may have contributed to this shift.