Distribution of Streptococcus mutans,Bifidobacterium and Lactobacillus among preschool children with different caries status

AIM: To quantitatively determine the composition of probiotics and Streptococcus mutans in saliva among preschool children.METHODS: Thirty preschool children with dmft ≥4 and thirty preschool children with dmft=0,designated as high-caries and non-caries group respectively,were enrolled in this clinical study.Stimulatory saliva was collected from all children.The saliva was then inoculated into selective culture medium of Streptococcus mutans,Bifidobacterium and Lactobacillus,cultured under anaerobic conditions at 37 ℃ for 48 h.The bacteria were observed under microscope after HE staining.RESULTS: The number of Streptococcus mutans in all saliva samples was significantly higher than that of Lactobacillus or Bifidobacteria(P0.05).No significant difference in the number of Streptococcus mutans was observed between high-caries group and non-caries group(P0.05).The number of Lactobacillus or Bifidobacteria was significantly higher in non-caries group than in high-caries group(P0.05).CONCLUSION: The number of Lactobacillus or Bifidobacteria is higher in non-caries preschool children.Increasing the number of Bifidobacterium and Lactobacillus may help to decrease caries incidence.