[Preliminary study on genotypic diversity of Streptococcus mutans in Xinjiang Uygur preschool children].

OBJECTIVE

To investigate the relationship between genotypic diversity of Streptococcus mutans (Sm) and deciduous teeth caries in Xinjiang Uygur autonomous region.

METHODS

Isolates of Sm were obtained from 17 caries-free and 17 caries-active Uygur preschool children aged from 3 to 5 years. A total of 143 isolates were subcultured, biochemically characterised and identified by polymerase chain reaction (PCR) as Sm and Streptococcus sobrinus (Ss). Then the Sm isolates were genotyped by arbitrarily primed-PCR (AP-PCR).

RESULTS

A total of 81 Sm isolates from caries-active subjects and 62 isolates from caries-free subjects were identified by PCR and forty distinct genotypes identified from 143 clinical isolates. In seventeen caries-active group, 9 children had only 1 genotype, 5 children had 2 genotypes, 3 children had 3 genotypes. In seventeen caries-free group, 14 children had only 1 genotype, 3 children had more than 2 genotypes. The Spearman correlation test showed a strong association between genotypic diversity and caries experience (r = 0.342, P < 0.05).

CONCLUSIONS

Isolates of Sm in caries-active Uygur preschool children show apparent more genetic diversity than those in caries-free children. The genotypes of isolates might be related to differences in caries susceptibility.