AP-PCR基因指纹用于变形链球菌传播株与非传播株的筛选

Detection of the Transmitted Strains and Non-transmitted Strains of Mutans Streptococci by AP-PCR

目的 应用AP_PCR基因指纹筛选变形链球菌 (mutansstreptococci,MS)的传播株 (transmittedstrains)与非传播株 (nontransmittedstrains) ,探讨影响MS传播的因素。方法 选取 2 0对口腔中已定居有MS的儿童 (3～ 4岁 )与他们的母亲 ,取牙面菌斑样本涂于轻唾—杆菌肽培养基。每人随机挑取 4 5株分离株 ,提取染色体DNA ,AP_PCR基因指纹检测。结果 ①从 2 0 0个分离株中共分辨出 4 5个不同的基因型 ,其中 10位 (5 0 % )母亲和 15位 (75 % )儿童分别带有 1种类型 ,另 5位 (2 5 % )儿童带 2种类型 ,另 10位 (5 0 % )母亲带有 2种或 2种以上类型 (2位母亲带有 5种型 ) ,表明人群口腔中定居的MS存在基因多态性 ;②比较母亲与其子女MS基因型的相似性发现 ,2 0对母子中16对 (80 % )有相似基因型出现 ,提示MS在此人群中的高传播现象 ;③对有传播现象的 16位母亲的S.mutans进行传播株与非传播株的筛选发现 ,10 (5 0 % )位母亲口腔中传播株与非传播株共存 ,表明并非所有基因型的S .mutans都能传播。结论 ①AP_PCR基因指纹能清晰地分辨出S.mutans的传播株和非传播株 ;②在S .mutans的母婴传播过程中某一型菌株的优先传播是普遍存在的 。

Objective\ Dental caries is a transmissible infectious disease in which S.mutans plays the major role. The purpose of this study was to detect the S.mutans transmitted strains and non_transmitted strains by AP_PCR fingerprint for laying the foundation of study on the relation between bacterial properties of S.mutans and 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 (DMFT). Diet regime, breast feeding and care of the children were recorded. 200 Isolates of S.mutans were detected by S.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 isolates were 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 of S.mutans than their children. Comparisons in genotypes between children and their mothers discovered that 16(80%)children harbored the same genotypes as their mothers, indicating high transmission in the group of people. Detection of the S.mutans transmitted 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.mutans transmitted strains and non_transmitted strains. Some S.mutans genotypes had higher ability of transmission than others.