A Trial to Compare Antibacterial vs. Placebo Mouthwash to Reduce the Incidence of Sexually Transmitted Infections (STIs) in Men Who Have Sex With Men (MSM) Taking HIV Pre-Exposure Prophylaxis (PrEP)

The study aims to assess if there is a difference in the incidence rate of gonorrhea, chlamydia and syphilis detected at any site whilst individuals are on daily and pre/post sex Listerine cool mint (LCM) vs. placebo mouthwash. The study has a double‐blind, cross‐over design, in which subjects will be screened at the ITM and, if eligible, will be enrolled and randomized to group 1 (LCM) or group 2 (placebo). After 3 months, a crossover will occur and subjects will switch to the other intervention. Each participant will therefore be enrolled for 6 months (2 x 3 months, no wash out period). Subjects will be recruited from the existing PrEP cohort at the Institute of Tropical Medicine Antwerp. A total of 320 subjects will be recruited (160 in each arm).