Quantitative Assessment of Microbial Contamination and Patterns of Public Behaviour with Used Toothbrushes: Implications of Storage and Replacement

Introduction: Toothbrushes can readily become contaminated with microbes during use and storage. They present a potential hazard of cross-contamination and subsequent infection. Aims: To investigate the nature and level of microbial contamination of used toothbrushes and influence of participant lifestyle. Methods and Results: 103 used toothbrushes were donated, and microbial contents were determined by microbial culture and identification. 97% of toothbrushes revealed contamination. The microbial loads ranged from 0-1010 cfu/brush with median values of around 107, with Candida isolated in the highest levels. 90% of toothbrushes were stored in bathrooms presumably exposed to environmental contamination and 72% revealed the presence of enteric bacteria including Klebsiella, Serratia and Enterobacter. 50% of participants kept toothbrushes for >3 months and 40% retained toothbrushes for 4-6 months; microbial loads were fully established during the first three months of use and did not increase further with prolonged use. Only 57% of participants brushed their teeth twice a day and 41% brushed once a day. Conclusion: Used toothbrushes are heavily contaminated and the presence of potentially pathogenic microorganisms constitutes a potential health risk. Significance and Impact of Study: There is an under-recognised risk of cross-contamination/infection, especially when multiple users store toothbrushes in close contact. Guidance on toothbrush age, brushing frequency and storage is not being followed. Further education is required to improve public awareness.