[In vitro study of xylitol on the growth and acid production of Actinomyces viscosus].

Objective: This research aimed to study the inhibitory effect of xylitol on the growth and acid production of Actinomyces viscosus (A. viscosus).

Methods: We cultivated A. viscosus in anaerobic conditions with different concentrations (128, 64, 32, 16, 8, and 4 g x L(-1)) of xylitol brain heart infusion liquid medium and determined the minimum inhibitory concentration (MIC). Subsequently, we measured the pH value of the control group, as well as those of 1/2, 1/4, 1/8 MIC, and MIC concentration groups at 1.5, 3, 6, 12, 24, and 48 h. The Delta pH and OD550 at 2, 4, 6, 8, 10, and 12 h were calculated. We discovered that the minimum xylitol concentrations suppressed 50% and 90% A. viscosus biofilm formation (i.e., MBIC50 and MBIC90). SPSS 19.0 was used to analyze the collected data, and conclusions were drawn afterward.

Results: Xylitol inhibited the growth ofA. viscosus at MIC of 64 g x L(-1). After 12 h, the differences of pH value among groups were all statistically significant (P < 0.05), and Delta pH increased when the MIC concentration decreased. Except for the 1/2 MIC and MIC groups, the differences of OD550 among groups had no statistical significance (P>0.05), and OD550 also increased when the MIC concentration decreased. These results imply that the ability ofA. viscosus to grow and produce acid in 1/2 MIC and MIC conditions will be reduced with the increase in xylitol concentration. The value of MIBC50 was 64 g x L(-1), whereas the value of MIBC90 was 128 g x L(-1). This finding indicates that the xylitol medium can restrict A. viscosus biofilm formation.

Conclusion: Xylitolcan effectively inhibit the growth, adhesion, and acid production ofA. viscosus, protecting teeth from cariogenic bacteria and preventing caries to a certain extent.