Antimicrobial properties of a mouthrinse for patients receiving radiation therapy

Objectives: The aim of this study was to test the antimicrobial properties of an experimental mouthrinse to assess its suitability for use in patients who require radiation therapy. Methods: The mouthrinse contained a mixture of glycerine, potassium nitrate and sodium fluoride. The minimal inhibitory concentration (MIC) of these ingredients was determined by recording the percentage kill against Candida albicans, Staphylococcus aureus and Streptococcus mutans over 24 hours at different concentrations. As controls, chlorhexidine digluconate and the commercial product Plax (Colgate) were also tested. Materials showing antimicrobial activity were then tested to determine the percentage kill over 1, 2, and 3 minute time periods. Each test was repeated three times: there were no significant differences between repeat tests. Results: The MICs for glycerine were 10%, 25% and 10% for C.albicans, S.aureus and S.mutans respectively. Potassium nitrate and sodium fluoride had no antimicrobial effect. The MIC of chlorhexidine was 0.02, and Plax 0.002 for each of the organisms tested. The glycerine was used at a 30% concentration in the experimental mixture, which killed 99.78%, 99.88%, 99.98% of C.albicans; 61.74%, 70.64%, 85.09% of S.aureus and 91.72%, 99.47%, 99.99% of S.mutans after 1, 2 and 3 minutes respectively. Chlorhexidine at 2% killed 98.98%, 99.89%, 99.99% of C. albicans; 95.83%, 99.68%, 99.97% of S.areus, and 99.89%, 99.96%, 99.99% of S.mutans after 1, 2, and 3 minutes respectively. Plax at its commercial concentration killed 99.99%, 99.99%, 99.99% of C.albicans, 99.66%, 99.99%, 99.99% of S.aureus, and 83.23%, 97.37%, 99.30% of S.mutans after 1, 2, and 3 minutes. Conclusion: A mouthwash effective in relieving oral symptoms in patients receiving radiation therapy needs to show some antimicrobial activity against in particular, C.albicans and S.mutans, whilst at the same time having a palliative effect. It would seem that the experimental mouthwash shows promise in fulfilling these requirements.