2008 Volume 27 Issue 1 Pages 145-148
In this study, the bactericidal activity of antibacterial monomer MDPB (12-methacryloyloxydodecylpyridinium bromide) against Streptococcus mutans was tested by a rapid method for monitoring viability. To S. mutans culture containing fluorescence staining solution that distinguishes live from dead cells, MDPB was added at a concentration of 250, 100, 50, or 10 μg/ml. Bacterial cells were observed by fluorescence microscopy and the percentage of dead cells was calculated. After 10, 20, or 30 minutes′ contact with MDPB, the live/dead ratio was measured by fluorometry and viable counts (CFU) determined by the conventional plating method.
Viability staining revealed that MDPB exhibited significant bactericidal effects at 50 μg/ml or greater (ANOVA, Fisher's PLSD test), and complete killing of the cells at 250 μg/ml of MDPB was demonstrated in conjunction with a plating method. The staining method thus provided a sensitive means to determine loss of viability, and indicated the strong killing effects of MDPB on S. mutans.
