Evaluation of the Microbiome in Men Taking Pre-exposure Prophylaxis for HIV Prevention.

Tenofovir-based regimens as pre-exposure prophylaxis (PrEP) are highly effective at preventing HIV infection. The most common side-effect is gastrointestinal (GI) distress which may be associated with changes in the microbiome. Dysbiosis of the microbiome can have numerous health-related consequences. To understand the effect of PrEP on dysbiosis, we evaluated 27 individuals; 14 were taking PrEP for an average of 171 weeks. Sequencing of 16S rRNA was performed using self-collected rectal swabs. Mixed beta diversity testing demonstrated significant differences between PrEP and non-PrEP users with Bray-Curtis and unweighted UniFrac analyses (p = 0.05 and 0.049, respectively). At the genus level, there was a significant reduction in Finegoldia, along with a significant increase in Catenibacterium and Prevotella in PrEP users. Prevotella has been associated with inflammatory pathways, insulin resistance and cardiovascular disease, while Catenibacterium has been associated with morbid obesity and metabolic syndrome. Overall, these results suggest that PrEP may be associated with some degree of microbiome dysbiosis, which may contribute to GI symptoms. Long-term impact of these changes is unknown.