ANALYSIS OF INTRAFAMILIAL TRANSMISSION OF MUTANS STREPTOCOCCI USING DNA FINGERPRINTING

1.口腔内变形链球菌的数量对9个家族35人700株变形链球菌进行同源性判别，发现许多人口腔内存在1 ~ 3种变形链球菌。2.母亲是变形链球菌主要传播媒介的分子生物学证据，17名儿童中有14名（82.3%）的母亲携带同一株变形链球菌。在这些孩子中，有三个孩子与母亲身上发现的菌株完全相同。五名儿童的菌株仅由他们的母亲和父亲传播。7名儿童的菌株与其父母的菌株无同源性。三个孩子的血统与他们父亲的血统相同。这些结果表明，儿童变形链球菌菌株是从他们的家庭传播。3.变形链球菌与传播有关的生化特异性经传播的变形链球菌合成不溶性葡聚糖的量比未传播的变形链球菌高1.10 ~ 2.47。在合成的葡聚糖中含有的不溶性葡聚糖的比例在传播菌株中为79.1 - 90.5%，高于未传播菌株的18.4 - 88.7%。接触角的数值表明细菌的疏水性，在14 °以下的所有菌株中，接触角都小于其他菌株。这些发现揭示了变形链球菌的传播应该与不溶性葡聚糖合成的粘附因素或接触角有关。

I studied the intrafamilial transmission of mutans streptococci using DNA fingerprinting.1.Number of strain of mutans streptococci in oral cavity.The discrimination of homology of 700 strains of mutans streptococci separated from 35 persons in 9 families revealed that one to three species inhabit in oral cavity in many subjects. Approximately 48.6% of subjects have two species of mutans streptococci.2.The molecular biological proof concerning that mother is predominant mediator of transmission of mutans streptococci.Approximatelly 82.3% of children (14 children of 17) had the same strain found in their mothers. In these children three children had all of the same strains found in mothers. The strains of five children were transmitted from only their mothers and fathers. The homology of strains of seven children were not found in their parents. The strains of three children were the same of the strains of their fathers. These results show that strains of mutans streptococci in children were transmitted from their families. especially their mother at high probability.3.The biochemical specificity of mutans streptococci concerning of transmissionThe amount of synthesis of insoluble glucan in transmitted mutans streptococci was 1.10 to 2,47 more than untransmitted strains. The proposions of insoluble glucan contained in the synthesized glucan were higher in the transmitted strains at 79.1 to 90.5% than that of untransmitted strains indicated at 18.4 to 88.7%. The values of contact angle, shows hydrophobicity of bacteria, indicated smaller in all the transmitted strains below 14ﾟ than other strains. These findings revealed that the transmission of mutans streptococci should concern the adherent factors of insoluble glucan synthesis or contact angle.