The Relationship Between Insertive Oral and Anal Sex and Select Measures of the Composition of the Urethral Microbiota Among Men Who Have Sex With Men

Abstract

Background Sexual behavior may influence the composition of the male urethral microbiota, but this hypothesis has not been tested in longitudinal studies of men who have sex with men (MSM). Methods From 12/2014-7/2018, we enrolled MSM with non-gonococcal urethritis (NGU) attending a sexual health clinic. Men attended five in-clinic visits at 3-week intervals, collected weekly urine specimens at home, and reported daily antibiotics and sexual activity on weekly diaries. We applied broad-range 16S rRNA gene sequencing to urine. We used generalized estimating equations to estimate the association between urethral sexual exposures in the prior 7 days (insertive oral sex [IOS] only, condomless insertive anal intercourse [CIAI] only, IOS with CIAI [IOS + CIAI], or none) and Shannon index, number of species (observed, oral indicator, and rectal indicator), and specific taxa, adjusting for recent antibiotics, age, race/ethnicity, HIV, and pre-exposure prophylaxis. Results Ninety-six of 108 MSM with NGU attended ≥1 follow-up visit. They contributed 1,140 person-weeks of behavioral data and 1,006 urine specimens. Compared to those with no urethral sexual exposures, those with IOS only had higher Shannon index (P = 0.03) but similar number of species and presence of specific taxa considered, adjusting for confounders; the exception was an association with Haemophilus parainfluenzae. CIAI only was not associated with measured aspects of the urethral microbiota. IOS + CIAI was only associated with presence of H. parainfluenzae and Haemophilus. Conclusions Among MSM after NGU, IOS and CIAI did not appear to have a substantial influence on measured aspects of the composition of the urethral microbiota.