Associations between Anorectal Chlamydia and Oroanal Sex or Saliva Use as a Lubricant for Anal Sex: A Cross-sectional Survey

Background Receptive condomless anal sex is a known risk factor for anorectal chlamydia, but it remains unclear whether oroanal sex practices also contribute. We aimed to determine whether oroanal sex ("rimming"), fingering, or the use of saliva as anal lubricant are risk factors for anorectal chlamydia among men who have sex with men (MSM). Methods This cross-sectional study was conducted at Melbourne Sexual Health Centre from July 2014 to June 2015. Routinely collected computer-assisted self-interview data included demographics, number of sexual partners, and condom use. We added questions on receptive rimming, receptive fingering or penis "dipping," and the use of a partner's saliva as anal lubricant. Results A total of 1691 MSM completed the questionnaire and tested for anorectal chlamydia. In univariable analyses, anorectal chlamydia was associated with using a partner's saliva as lubricant (odds ratio [OR] 1.97, 95% confidence interval [CI] 1.26-3.09), receptive rimming (OR 1.59; 95% CI 1.04-2.45), and receptive fingering or dipping (OR 1.90; 95% CI 1.06-3.43). In multivariable analysis, anorectal chlamydia was not associated with these sexual practices, after adjusting for number of sexual partners, HIV status, known contact with chlamydia, and condom use. However, collinearity between sexual practices likely obscured associations with anorectal chlamydia, and further analyses suggested weak associations between these sexual practices and anorectal chlamydia. Conclusions The use of a partner's saliva during receptive anal sex practices such as rimming, fingering, or penis dipping were weak risk factor for anorectal chlamydia in MSM. This contrasts with our previously reported findings that the use of saliva as anal lubricant is more strongly associated with anorectal gonorrhea.