Effect of Xylitol on the Growth and Survival of Streptococcus pneumoniae

Background: Xylitol has been applied in dentistry to prevent dental caries for many years. However, it's anti-Streptococcus pneumoniae effects are unclear.Objectives: The aim of this study was to determine the anti-Streptococcus pneumoniae activity of xylitol.Methods: In this study, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of xylitol were determined by microdilution method and tetrazolium salt-based colorimetric (MTT) assay. The effective concentrations of xylitol in the presence and absence of fructose against growth and survival of S. pneumoniae were measured. Data were analyzed using univariate analysis and Kruskal-Wallis test.Results: The results showed that 5% to 7.5% concentrations of xylitol were associated with reduced number of S. pneumoniae cells. About 80% to 100% of S. pneumoniae cells were killed under laboratory conditions after 3 to 7 hours, respectively. MIC and MBC of xylitol against S. pneumoniae were 2.5% and 7.5% after 4 hours, respectively. We found significant changes in the number of viable cells (P ≤ 0.002).Conclusions: The results showed that the 5% and 7.5% concentrations of xylitol inhibit S. pneumoniae growth. However, the emergence of multi-drug resistance in S. pneumoniae has become a global concern and the S. pneumoniae 23-valent vaccine may not be able to protect against S. pneumoniae human pathogenic strains. Finding a non-related antibiotic agent may be useful for controlling S. pneumoniae infections.