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)

Not Applicable

Terminated

Conditions: Sexually Transmitted Diseases

Interventions: Other: Mouthwash with LCM
Other: Mouthwash with placebo

Registration Number: NCT03881007

Lead Sponsor: Institute of Tropical Medicine, Belgium

Brief Summary: The study involves a randomized placebo controlled trial that aims to assess if a mouthwash (Listerine cool mint, LCM) is able to reduce the cumulative incidence of gonorrhoea (Ng), chlamydia (Ct) and syphilis in men who have sex with men and receiving preexposure prophylaxis (PrEP) at the Institute of Tropical Medicine (ITM).

Detailed Description: 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).

Recruitment & Eligibility

Status: TERMINATED

Sex: Male

Target Recruitment: 343

Inclusion Criteria

Men aged 18 or more
Enrolled in Belgian PrEP program at ITM
Has had sex with another man in the previous year
Has had a symptomatic or asymptomatic STI (Ct/Ng/syphilis) in the previous 2 years
Willing to be enrolled in the cohort for 6 months and attend 3 monthly follow up visits
Willing to comply with the mouthwash study schema and willing to ask their casual partners to mouthwash pre- and post-sex
Prepared to fill out the online diary once a week
Able and willing to provide written informed consent

Exclusion Criteria

Currently using a mouthwash and unwilling to cease use of this mouthwash
Enrolment in another interventional trial
Tests HIV positive at screening

Study & Design

Study Type: INTERVENTIONAL

Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
LCM, then placebo	Mouthwash with placebo	Mouthwash with LCM for 3 months followed by mouthwash with placebo for 3 months.
Placebo, then LCM	Mouthwash with LCM	Mouthwash with placebo for 3 months followed by mouthwash with LCM for 3 months
LCM, then placebo	Mouthwash with LCM	Mouthwash with LCM for 3 months followed by mouthwash with placebo for 3 months.
Placebo, then LCM	Mouthwash with placebo	Mouthwash with placebo for 3 months followed by mouthwash with LCM for 3 months

Primary Outcome Measures

Name	Time	Method
Patient Counts of Ng Plus Ct Plus Syphilis in Each Study Arm for Each Period	3-month period following each intervention	The sum of new diagnoses of Gonnorhea (Ng), Chlamydia (Ct) and syphilis in a 3 month period on LCM/placebo. Each participant can only contribute one diagnosis of Ct and one diagnosis of Ng per visit - regardless of number of sites infected. Thus each participant can contribute up to 3 diagnoses (Ct/Ng/syphilis) at each visit. The diagnosis of Ng and Ct will be made via molecular testing and syphilis via Rapid Plasma Reagin test (RPR) and Treponema Pallidum Antibodies tests (TPA) according to currently used European case definitions.

Secondary Outcome Measures

Name	Time	Method
Difference in Incidence Rate of Ng Plus Ct Plus Syphilis Between LCM and Placebo After Controlling for Adherence With Daily and Pre/Post Sex Mouthwash	3-month period following each intervention	Incidence rate of Ng, Ct and syphilis between both groups (LCM and placebo) post controlling for adherence to mouthwash
Difference in Incidence Rate of Pharyngeal Ng Between Each Study Arm for Each Period	3-month period following each intervention	Incidence rate of new pharyngeal Ng cases in each allocation arm for each study period of 3 months.
Difference in Cumulative Numbers of Antibiotics Used Between Periods on LCM vs. Placebo	3-month period following each intervention	Cumulative number of antibiotics used between both groups (LCM and placebo) for each period
Difference in Incidence Rate of Ct (Combined Pharyngeal, Urethral and Rectal) Between Each Study Arm for Each Period	3-month period following each intervention	Incidence rate of new Ct cases in each allocation arm (LCM and placebo) for each study period of 3 months.
Difference in Incidence Rate of Syphilis Between Periods on LCM vs. Placebo	3-month period following each intervention	Incidence rate of new syphilis cases in each allocation arm (LCM and placebo) for each study period of 3 months.
Proportion of Days That Mouthwash is Used on a Daily Basis and Proportion of Casual Sex Contacts When Mouthwash is Used Pre or Post Sex	6-month period	Daily: Proportion of days in study used mouthwash at least daily Post sex: Proportion of casual sexual contacts in study when mouthwash used post sex. Pre sex: proportion of casual sexual contacts in study when mouthwash used pre sex