Sites in the oropharynx reached by different methods of using mouthwash: Clinical implication for oropharyngeal gonorrhoea prevention

Objectives: Oropharyngeal gonorrhoea is increasing among men who have sex with men and is commonly found in the tonsils and at the posterior pharyngeal wall. To address this rise, investigators are currently trialling mouthwash to prevent oropharyngeal gonorrhoea. We aimed to determine which parts of the oropharynx were reached by different methods of mouthwash use (oral rinse, oral gargle and oral spray). Methods: Twenty staff at Melbourne Sexual Health Centre participated in the study from March to May 2018. Participants were asked to use mouthwash mixed with food dye, by three application methods on three separate days: oral rinse (15 s and 60 s), oral gargle (15 s and 60 s) and oral spray (10 and 20 times). Photographs were taken after using each method. Three authors assessed the photographs of seven anatomical areas (tongue base, soft palate, uvula, anterior tonsillar pillar, posterior tonsillar pillar, tonsil, posterior pharyngeal wall) independently and scored the dye coverage from 0% to 100%. Scores were then averaged. Results: The mean coverage at the sites ranged from 2 to 100. At the posterior pharyngeal wall, spraying 10 times had the highest mean coverage (29%) and was higher than a 15 s rinse (2%, p=0.001) or a 15 s gargle (8%, p=0.016). At the tonsils, there was no difference in mean coverage between spray and gargle at any dosage, but spraying 20 times had a higher mean coverage than a 15 s rinse (42% vs 12%, p=0.012). Conclusion: Overall, spray is more effective at reaching the tonsils and posterior pharyngeal wall compared with rinse and gargle. If mouthwash is effective in preventing oropharyngeal gonorrhoea, application methods that have greater coverage may be more efficacious.