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Effect of rectal douching/enema on rectal gonorrhoea and chlamydia among a cohort of men who have sex with men on HIV pre-exposure prophylaxis
  1. Adiba Hassan1,
  2. Jill S Blumenthal1,
  3. Michael P Dube2,
  4. Eric Ellorin1,
  5. Katya Corado3,
  6. David J Moore4,
  7. Sheldon R Morris1
  1. 1 Antiviral Research Center, University of California San Diego School of Medicine, San Diego, California, USA
  2. 2 Department of Medicine, University of Southern California Keck School of Medicine, Los Angeles, California, USA
  3. 3 Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Division of HIV Medicine, Torrance, California, USA
  4. 4 Department of Psychiatry, University of California San Diego School of Medicine, San Diego, California, USA
  1. Correspondence to Adiba Hassan, Antiviral Research Center, University of California San Diego School of Medicine, San Diego, CA 92093, USA; adhassan{at}


Objectives Rectal douching/enema (RD) is a common practice among men who have sex with men (MSM) in preparation for sex. RD can break down the rectal mucosal barrier and potentially affect the rectal microbiome. The objective of this study was to understand if RD is associated with acquiring rectal infections (RI) with rectal gonorrhoea (NG) and/or chlamydia (CT).

Methods From 2013 to 2015, 395 adult HIV-uninfected MSM were enrolled in a randomised controlled study for pre-exposure prophylaxis (PrEP) adherence with routine sexual risk survey and testing. Using data from this cohort, baseline differences by RI were assessed using Pearson’s χ² and Wilcoxon-Mann-Whitney test. Association between RD and RI was modelled using multivariable logistic regression adjusted for potential confounders (sexual behaviour, substance use and age) selected a priori. Effect modification by number of male partners and sensitivity analysis to rule out reverse causality were also conducted.

Results Of 395 participants, 261 (66%) performed RD and 133 (33%) had at least one NG/CT RI over 48 weeks. Number of condomless anal receptive sex (med: 4, p<0.001), male partners (med:6, p<0.001) and substance use (any of methamphetamine/hallucinogens/dissociative/poppers) (p<0.001) were associated with increased odds of RI. Controlling for potential confounders, odds of prevalent RI were 3.59 (p<0.001, 95% CI 1.90 to 6.78) and incident RI 3.87 (p=0.001, 95% CI 1.78 to 8.39) when douching weekly or more compared with not douching. MSM with more than six male partners had 5.34 (p=0.002, 95% CI 1.87 to 15.31) increased odds of RI when douching weekly or more compared with not douching.

Conclusion Rectal hygiene with RD is a common practice (66%) among HIV-uninfected MSM on PrEP in this study, which increases the odds of acquiring rectal NG and/or CT independent of sexual risk behaviour, substance use and other factors. This suggests interventional approaches targeting rectal hygiene products and practices could reduce sexually transmitted infections.

  • gonorrhoea
  • chlamydia infection
  • sexual behaviour

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  • Handling editor Stefan Baral

  • Contributors AH and SRM drafted and finalised manuscript with contributions from all authors. SRM, DJM, MPD, KC and JSB designed and conducted clinical study. EE assisted with implementation and data acquisition. AH and SRM conducted statistical analysis. All authors interpreted data, reviewed drafts and approved final version.

  • Funding Data for this study were collected as part of the main CCTG 595 study supported by the California HIV Research Program (CHRP- MC08-SD-700 and EI-11-SD-005).

  • Competing interests None declared.

  • Patient consent Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement Data can be available at request to corresponding author.