Rectal Douching is not associated with Incident Rectal Gonorrhea or Chlamydia among Men Who Have Sex with Men (MSM)

Prior studies have identified an association between rectal douching and prevalent rectal Neisseria gonorrhoeae (GC) and Chlamydia trachomatis (CT), but few studies have examined associations with incident infections. We implemented a case-crossover study nested within the ExGen study, a 48-week cohort study conducted in Seattle, Washington, 2016-2018. Each week, ExGen participants completed a survey and self-collected rectal specimens, which were tested for CT and GC via nucleic acid amplification testing (NAAT) at the end of the study. We identified individuals who had an incident rectal GC or CT infection, defined as two consecutive weeks of a positive NAAT. For each individual, we selected 1 case-week (defined as the first week of an individual’s first incident rectal GC or CT infection) and 2 randomly-selected control-weeks (defined as weeks where the participant tested negative for rectal GC or rectal). We used multivariate conditional logistic regression to estimate the adjusted odds ratio (aOR) and 95% confidence interval (CI) for the association between douching and rectal GC/CT, adjusting for condomless receptive anal sex (RAS) events in the past week and concurrent GC or CT infection. There were 140 individuals in ExGen. Our analytic sample comprised 17 GC case-weeks and 34 matched GC control-weeks, and 22 CT case-weeks and 44 matched CT control-weeks. Participants reported douching during 64.7% of GC case-weeks and 70.6% GC control-weeks (aOR=0.55; 95% CI=0.11-2.80). Water was used during 91% of case-weeks and 96% of control-weeks in the GC analysis. Douching was reported at a nearly identical frequency among CT case-weeks (45.5%) versus CT control weeks (47.7%) (aOR=1.16; 95% CI=0.27 – 5.07). Water was the only douching solution reported among participants in the CT analysis. Water-based douching does not appear to increase the risk of incident rectal GC/CT.