2021 Volume 70 Issue 1 Pages 32-39
It has been reported overseas that oral care using mouthwash reduces the risk of developing pneumonia. However, the concentrations of some active ingredients in mouthwashes in Japan are lower than those reported overseas owing to Japanese regulations, because mouthwashes are primarily intended to prevent oral diseases and not to protect against pneumonia-causing pathogens. In this study, we determined whether the different active ingredients used in mouthwashes could have a sufficient bactericidal effect against pneumonia-causing pathogens. The experiments were performed with slight modifications of the European standard EN 1040. Chlorhexidine gluconate (CHG), cetylpyridinium chloride (CPC), and 1,8-cineole were adjusted to concentrations commonly found in commercially available mouthwashes in Japan. After each bacterial pathogen was cultured for 18 h in suspensions, bacterial cells were harvested and washed with PBS. Subsequently, the bacterial cell concentrations were adjusted to 108 CFU/mL and standardized at OD 660 nm. The bacterial cell suspensions were then reacted with mouthwash ingredients for 10, 20, 30, and 60 s. Thereafter, each neutralized and diluted mixture was spread onto an agar plate and incubated for 18 h at 35°C. Later, the number of bacterial cells was counted. At the concentration used in mouthwashes, CPC was effective against pneumonia-causing pathogens. Furthermore, it was found that CPC exerted sufficient bactericidal effect at concentrations lower than that used in mouthwash. CHG was effective against some pneumonia-causing pathogens. It was also found to be effective even at concentrations lower than the previously reported concentrations (0.12–0.20%).
