The Genotype And Transmission Analysis Of Streptococcus Mutans In The Oral Cavity Of The Child

Objective The purpose of this experiment was to analyze the difference of the number of S.mutans genotype and the source of S.mutans transmission in high-caries and caries-free child, and furtherly explore the relationship between the number of S.mutans genotype and caries activity.Methods 20 pairs S.mutans -colonized mother-child were tested and 800 strains were isolated from them. Then the genotypes of 20 pairs mother-child were detected by AP-PCR genotyping to observe the difference of number of S.mutans genotype and the source of S.mutans transmission in high-caries and caries-free child. Statistical analyses were carried out with the SPSS software, the level of significance was set to P<0.05.Results A total of 800 S.mutans isolates were isolated from 20 pairs S.mutans-colonized mother-child. 800 S.mutans isolates were analyzed by AP-PCR, and 73 different genotypes were identified. In 10 high-caries children, 2 possessed 1 genotype, 2 possessed 2 genotype, 3 possessed 3 genotypes, 3 possessed 4 genotypes. In 10 mothers of high-caries child, 2 possessed 1 genotype 1 possessed 2 genotypes, 5 possessed 3 genotypes, 1 possessed 4 genotypes, 1 possessed 8 genotypes. In 10 caries-free children, 8 possessed 1 genotype, 2 possessed 2 genotypes, In 10 mothers of caries-free child, 4 possessed 1 genotype, 5 possessed 2 genotypes, 1 possessed 3 genotypes. 12 of 20 pairs mother-child possessed the same S.mutans genotype, the number of the same S.mutans genotype was 6 in high-caries pairs and 8 in caries-free pairs. The same S.mutans genotype was detected among two and three children respectively from unrelated families attending the same nursery. The mother of high-caries child had significantly higher DMFT scores than mother of caries-free child (F=9.39, P<0.01). The number of S.mutans genotype harbored in high-caries child was more than the number of genotype present in caries-free child (F=4.52, P<0.05). The number of S.mutans genotype harbored in the mother of high-caries child was significantly more than the number of genotypes present in the mother of caries-free child (F=14.78, P<0.01).There was no significant difference in the number of the same S.mutans genotype of 10 high-caries pairs and 10 caries-free pairs (F=0.45, P>0.05).Conlusion The genotype diversity of S.mutans strains was shown in the oral cavity of the mother and child. The same genotype detected in mother-child pairs suggests the vertical transmission of S.mutans. The same genotype detected in children of the same nursery suggests the horizontal transmission of S.mutans. The number of S.mutans genotypes harbored in high-caries person was more than the number of genotype present in caries-free person. The number of S.mutans genotypes harbored in person might relate to the caries activity.