Abstract:

Objective　Dental caries is a transmissible infectious disease in whichS.mutansplays the major role. The purpose of this study was to detect theS.mutanstransmitted strains and non-transmitted strains by AP-PCR fingerprint for laying the foundation of study on the relation between bacterial properties ofS.mutansand its transmission.Methods　Plaque samples were obtained from buccal surfaces of 20 3~4 years old children and their mothers. Caries experience was scored by dmft (DM- FT). Diet regime, breast feeding and care of the childrenwere recorded. 200 Isolates ofS.mutanswere detected byS.mutansB medium and confirmed biochemically. DNA from each isolate was purified and AP-PCR fingerprinting was conducted. Amplicons were separated by electrophoresis in 1·5% agarose gels.Results　45 different patterns among the 200 isolateswere found. There were 10 mothers (50%) and 15(75%) children owning one genotype while 10 mothers and 5 children owning more than one (2 mothers owning 5 types). The data showed that the mothers harbored a more heterogeneous population ofS.mutansthan their children. Comparisons in genotypes between children and theirmothers discovered that 16(80%)children harbored the same geno- types as their mothers, indicating hightransmission in the group of people. Detection of theS.mutanstransmitted strains and non- transmitted strains in mothers demonstrated that 10 (50%) mothers harbored not only transmitted strains but also non-transmitted strains, suggesting that different strains had different ability of transmission.Conclusion　AP-PCR was capable of detecting the S.mutanstransmitted strains and non-transmitted strains. SomeS.mutansgenotypes had higher ability of transmission than oth- ers.

Key words: mutans streptococci, transmission, genotype, colonization, AP-PCR(arbitrarily primed polymerase chain reaction)