Genotypic diversity of Streptococcus mutans isolated from preschoolers with and without early dental care

Abstract Introduction Streptococcus mutans (S. mutans) exhibits extensive genotypic diversity, but the role of this variation is poorly understood. Objective To evaluate the genotypic diversity of S. mutans in preschoolers with and without early dental care and to associate it with dental caries experience. Material and method Twenty children, aged five year old, with history of dental care since they were one year old (G1) and 20 children without history of dental care (G2) were included. Their oral health status was assessed by the dmft index. S. mutans samples were isolated from the saliva and analysed by polymerase chain reaction. A total of 339 S. mutans isolates (173 from G1 and 166 from G2) were genotyped by random amplified polymorphic DNA with arbitrary primers OPA-02 and OPA-13. Result The results revealed 75 distinct genotypes of S. mutans in G1 and 73 in G2. Furthermore, G1 and G2 subjects harboured one to eight and one to seven distinct genotypes of S. mutans, respectively. A statistically significant association (P=0.021) and a moderate correlation (r= 0.503) were observed between dental caries experience and genotypic diversity of S. mutans in G1. Conclusion From the limitations of the study design, we just can hypothesize that actions of early dental care carried out by an educative-preventive program can contribute to a distinct oral microbiota.

摘要
引言
变形链球菌（Streptococcus mutans，S. mutans）具有广泛的基因型多样性，但目前对该基因变异的生物学作用尚不明晰。
目的
本研究旨在评估有/无早期口腔护理史的学龄前儿童体内变形链球菌的基因型多样性，并探讨其与龋病患病经历的关联。
材料与方法
本研究纳入20名自1岁起即接受口腔护理的5岁儿童（G1组），以及20名无口腔护理史的5岁儿童（G2组）。采用乳牙龋失补牙数（dmft）评估两组儿童的口腔健康状况。从唾液样本中分离变形链球菌，通过聚合酶链式反应（PCR）进行检测分析。总计339株变形链球菌分离株（G1组173株，G2组166株）采用随机扩增多态性DNA（RAPD）技术，以随机引物OPA-02和OPA-13完成基因分型。
结果
结果显示，G1组中共检出75种不同的变形链球菌基因型，G2组为73种。进一步分析发现，G1组受试者体内的变形链球菌基因型数量为1~8种，G2组为1~7种。在G1组中，龋病患病经历与变形链球菌基因型多样性之间存在统计学意义的关联（P=0.021），且二者呈中等程度相关（r=0.503）。
结论
鉴于本研究设计存在一定局限性，本研究仅能提出假说：由教育预防项目实施的早期口腔护理措施，可能对口腔微生物群的组成产生显著影响。