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目的:探讨变形链球菌葡糖基转移酶催化活性区cat基因的遗传多态性与不同龋敏感儿童龋病发生的关系。方法:随机选取60名3～5岁的高龋、中龋及无龋儿童,取牙面菌斑样本接种于MS培养基上,每人随机挑取1～5株临床分离株,提取细菌染色体DNA,经PCR扩增cat基因片段,分别采用限制性内切酶HinfⅠ、MboⅠ、TaqⅠ进行限制性片段长度多态性分析,对不同龋敏感者口腔变形链球菌临床分离株进行基因分型。结果:不同龋敏感儿童变形链球菌临床分离株经限制性内切酶HinfⅠ酶切后,限制性片段长度多态性分析酶谱出现了差异,且各组差异经卡方分析有统计学意义。MboⅠ、TaqⅠ限制性内切酶酶切后,限制性片段长度多态性分析酶谱没有差异。结论:不同龋敏感儿童变形链球菌葡糖基转移酶催化活性区cat基因型不同,并可能在一定程度上与变形链球菌利用葡糖基转移酶合成胞外多糖的能力相关。
Objective: To investigate the relationship between the genetic polymorphisms of the cat gene in the catalytically active area of Streptococcus mutans glucosyltransferase and the occurrence of dental caries among children with different caries-susceptible. Methods: Sixty caries, caries-free and caries-free children aged 3 to 5 years old were randomly selected. The dental plaque samples were inoculated on MS medium. One to five clinical isolates were randomly selected from each patient to extract bacterial chromosomes DNA. The cat gene fragment was amplified by PCR. Restriction endonucleases Hinf Ⅰ, Mbo Ⅰ and Taq Ⅰ were used to analyze the restriction fragment length polymorphism. The clinical isolates of S. mutans from different caries-sensitive individuals were genotyped. Results: The results of restriction fragment length polymorphism (PCR) analysis showed that there was a significant difference in the zymogram of the Streptococcus mutans isolates from different caries-sensitive children after being digested with restriction endonucleases Hinf Ⅰ. After Mbo I and Taq I restriction endonuclease digestion, there was no difference in restriction fragment length polymorphism. CONCLUSIONS: Cat genotypes of glucosyltransferase active regions in Streptococcus mutans of different caries-sensitive children are different, and may be related to the ability of Streptococcus mutans to synthesize extracellular polysaccharides by using glucosyltransferase to a certain extent.