Douching is associated with rectal inflammation and microbial community shifts in sexual minority men

Background: Rectal douching is prevalent among sexual minority men (SMM) that engage in condomless receptive anal intercourse (CRAI). CRAI is associated with elevated rectal inflammation, which is linked with HIV acquisition risk. Douching alone may contribute to rectal inflammation and microbial community disruption, however this association has not been well defined.Methods: HIV-negative SMM reporting CRAI (n=92; median age=34.6 years) were surveyed regarding douching. Rectal cytokine/chemokine levels and microbial community structure were assessed via bead-based immunoassay and 16s rRNA sequencing, respectively. Regression models, differential abundance testing, and correlation testing were used to assess associations between douching, CRAI, microbiome composition, and rectal cytokine/chemokine levels.Results: Participants that reported douching had a higher number of CRAI partners, elevated rectal cytokine/chemokine levels, and lower microbial richness, evenness, and Shannon diversity, as compared to non-douching participants. Significant correlations were observed between rectal cytokine/chemokine levels, alpha-diversity metrics and individual microbial genera.Conclusions: These findings have clinical importance, as elevated rectal inflammation and microbial community balances have been linked with HIV acquisition. Further research is needed to elucidate the mechanisms by which douching, alone and with CRAI, may induce rectal inflammation and microbial dysbiosis and develop methods to mitigate these changes to reduce HIV susceptibility.