[Study on the horizontal transmission of oral Streptococcus mutans in day-nursery children].
OBJECTIVE
To analyze genotypic diversity of oral Streptococcus mutans (S. mutans) and find out horizontal transmission possibility of the microbe in day-nursery children.


METHODS
The plaque samples were scratched with sterilized toothpicks from teeth of 32 day-nursery children aged between 3 and 4, then cultured on MSB plates. Clones with representative S. mutans-like were subcultured and identified to species level biochemically. AP-PCR fingerprinting was performed to distinguish genotypic diversity of those isolates. Then S. mutans isolated from different children with very similar amplicon profiles were examined by chromosomal DNA fingerprinting analysis.


RESULTS
S. mutans were isolated in oral cavities of 78.1% children, 100% in caries and 69.6% in caries-free children. A total of 57 genotypes were identified by AP-PCR. More than one amplitypes were identified in 88% of the 25 children with S. mutans colonization. Two pair of children shared common genotypic S. mutans.


CONCLUSIONS
There is no evident relation between number of genotype detected and caries. The presence of matching genotypes of S. mutans among day-nursery children suggests the horizontal transmission may exist.
Shang
Ran
R
Key. Laboratory of Oral Biomedical Engineering of Ministry of Education, Sichuan University, Chengdu 610041, China.
Zou
Jing
J
Zhou
Xue-Dong
XD
D002648:Child; D003731:Dental Caries; D003773:Dental Plaque; D005838:Genotype; D006801:Humans; D009724:Nurseries, Infant; D016133:Polymerase Chain Reaction; D013295:Streptococcus mutans; D014070:Tooth