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.

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 December 2014 to July 2018, we enrolled MSM with nongonococcal urethritis (NGU) attending a sexual health clinic. Men attended 5 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 preexposure prophylaxis.
Results: Ninety-six of 108 MSM with NGU attended ≥1 follow-up visit. They contributed 1140 person-weeks of behavioral data and 1006 urine specimens. Compared with 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 seem to have a substantial influence on measured aspects of the composition of the urethral microbiota.
Competing Interests: Conflict of Interest of Sources of Funding: This work was supported by the National Institutes of Health (grant number U19 AI113173). L.C.C. was supported by the National Institutes of Health (grant number TL1 TR002318 trainee support). K.A.T. was supported by the University of Washington/Fred Hutch Center for AIDS Research, a program funded by the National Institutes of Health (grant number P30 AI027757). Study data were collected and managed using Research Electronic Data Capture (REDCap) tools hosted at the University of Washington Institute of Translational Health Sciences and supported by the National Institutes of Health (grant number UL1 TR002319). C.M.K. has received donations of test kits and reagents from Hologic, Inc. M.R.G. has conducted studies unrelated to this work supported by grants from Hologic, Inc. L.E.M. has received research support and honoraria from Hologic, Inc., and Nabriva Therapeutics. All other authors declare that they have no conflict of interest.
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