# A randomized crossover study to evaluate the efficacy of antibacterial mouthwash in preventing pharyngeal gonorrhea among a high risk population

> **NIH NIH R21** · UNIVERSITY OF CALIFORNIA LOS ANGELES · 2020 · $173,462

## Abstract

Gonorrhea is one of the most commonly reported infectious diseases in the United States and has increased
substantially in recent years. The prevalence of gonorrhea, including pharyngeal gonorrhea is particularly high
among men who report male sex partners. Between 2010 and 2017 the estimated rates of gonorrhea
increased by 283% among men who report male sex partners, which was significantly higher than the 80%
increase seen among other men in the United States. Oral (i.e., pharyngeal) infections with gonorrhea are
thought to be a major driver of these increasing rates. Interventions to reduce pharyngeal gonorrhea have the
potential for significant population impact on the overall incidence of gonorrhea. Preliminary data suggest a
protective effect of commercially available mouthwash (antibacterial Listerine® mouthwash) against
pharyngeal gonorrhea. Given that mouthwash is widely available, easy to use, and relatively inexpensive it
has the potential to serve as an important gonorrhea prevention strategy among a highly impacted population.
However, further studies are needed to understand whether the inhibitory effects of mouthwash on overall
bacterial load in the oral cavity translate to reduced risk of acquisition of pharyngeal gonorrhea. Therefore, the
objectives of this study are to: (1) examine the acceptability of daily mouthwash use for the prevention of
pharyngeal gonorrhea; and (2) measure the preliminary efficacy of daily use of antibacterial mouthwash as
compared to a placebo mouthwash in reducing the incidence of pharyngeal gonorrhea among a cohort of high
risk men. To accomplish this we propose to conduct a study that will leverage an existing cohort study
designed to assess the epidemiological and immunological impact of substance use and HIV on minority men
who have sex with men (mSTUDY). We will use a randomized crossover study design and participants in the
proposed study will be those enrolled in the mSTUDY who have been previously diagnosed with pharyngeal
gonorrhea. Half the participants will be randomized to first receive either the antibacterial mouthwash or the
placebo mouthwash and all participants will be tested for pharyngeal gonorrhea at 12-weeks post intervention.
At the 12-week mark participants will `crossover' to the alternative intervention group from which they were
randomized at baseline. In this way, those assigned to the active mouthwash group will switch to the placebo
mouthwash and vice versa and all participants will then be followed for another 12-weeks and will be tested for
pharyngeal gonorrhea again after 12-weeks of cross-over intervention (i.e., 24 weeks following study
enrollment). Findings from this study will contribute to our understanding of its potential acceptability and
provide preliminary evidence of the efficacy of antibacterial mouthwash in preventing pharyngeal gonorrhea.

## Key facts

- **NIH application ID:** 9927073
- **Project number:** 1R21AI147969-01A1
- **Recipient organization:** UNIVERSITY OF CALIFORNIA LOS ANGELES
- **Principal Investigator:** Marjan Javanbakht
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $173,462
- **Award type:** 1
- **Project period:** 2020-03-19 → 2022-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9927073

## Citation

> US National Institutes of Health, RePORTER application 9927073, A randomized crossover study to evaluate the efficacy of antibacterial mouthwash in preventing pharyngeal gonorrhea among a high risk population (1R21AI147969-01A1). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9927073. Licensed CC0.

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