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Background: Sexual behaviors expose men to pathogens that may cause urethritis, but their frequency and sequence are understudied. We estimated the incidence of sexual behaviors and describe their sequence.
Methods: Heterosexual men ≥16 years attending the Seattle STD Clinic enrolled and returned for 6 monthly clinic visits, including clinic exam, specimen collection, and computerized self-interview. Nongonococcal urethritis (NGU) was defined as symptoms or urethral discharge plus ≥5 PMNs/HPF. Electronic diaries describing daily sexual exposures within the past 14 days were submitted every 2 weeks. Poisson regression with robust error variance yielded incidences and confidence intervals (CI).
Results: From 8/2014–3/2016, 110 men completed 947 diaries reporting on 13,258 diary-days. At enrollment, mean age was 31.7; 68% were White, median number lifetime partners was 15 (IQR=9-37), and 45 men (41%) had NGU. The median number diaries per man was 10 (IQR=4-13) and sexual activity occurred a median of 8% of diary-days per man (IQR=4-16%). Incidence of any sex was 0.86 per person-week (ppwk) (95% CI=0.73-1.02). Vaginal sex occurred most frequently (0.80 ppwk; 0.67-0.96), followed by receipt of oral sex, (0.46 ppwk; 0.36-0.58) and anal sex (0.04 ppwk; 0.02-0.07). Receiving rimming was rare (0.01 ppwk; 0.00-0.02). Although most days with sex (67%) involved >1 behavior, vaginal sex alone occurred in 28.6% of episodes and receipt of oral sex alone in 3.1%. The most common sequence of behaviors per episode was hand-to-genital contact, receipt of oral sex, then vaginal sex (27.9%). Vaginal sex was preceded by hand-to-genital contact in 14.5% and by receipt of oral sex in 8.5%. Anal sex alone occurred rarely (0.44%) and usually last in sequences. Condoms were used in 28.8% of vaginal and 11.8% of anal sex.
Conclusions: Multiple sexual exposures per episode were frequent but condom use was infrequent. Individual male urethral microbiomes are often exposed simultaneously to oral and vaginal bacteria.