OBJECTIVETo investigate the antagonistic effects of three species of oral Streptococcus on the growth of oral Saccharomyces albicans in vitro.

METHODSDirect inoculation method, reverse inoculation method and mixed culture methods were respectively chosen to observe the changes of Saccharomyces albicans colony formation on the effects of Streptococcus mutans, Streptococcus sanguis and Streptococcus salivarius.

RESULTS1) No clear inhibition zone was observed in each of the groups by direct inoculation method. 2) Compared with the control groups, Saccharomyces albicans colony formation on soft agar of Streptococcus sanguis decreased significantly (P < 0.05). 3) Mixed culture method results showed that Streptococcus mutans could inhibit the growth of Saccharomyces albicans significantly at different time points (P = 0.001). 4) Under the action of bacteria culture supernatant, the count of Saccharomyces albicans in experiment groups showed statistical significance when compared with the control groups at 24, 48, 72 h (P = 0.001); The differences among the experimental groups were of no statistical significance at majority times (P > 0.05).

CONCLUSIONStreptococcus mutans, Streptococcus sanguis, and Streptococcus salivarius could obviously inhibit the growth of Saccharomyces albicans in vitro. However, it is still unclear that among which the inhibition effects is stronger. The antagonistic effects is weakened gradually.