Department of Endodontics, Stomatology Hospital of Guangzhou Medical University, 59 Huangsha Thoroughfare, Guangzhou, China.
Mol Cell Biochem. 2012 Jun;365(1-2):159-64. doi: 10.1007/s11010-012-1255-5. Epub 2012 Mar 10.
The aim of the study was to identify the number and distribution of genotypes of Streptococcus mutans (S. mutans) and Streptococcus sobrinus (S. sobrinus) isolated from caries-free and caries-active subjects. Non-stimulated saliva, buccal smooth surface of the right upper teeth, fissures of sound occlusal surface, and carious surface were sampled from 7 caries-free and 7 caries-active (DMFT ≥ 6) students aged 22-24 years. S. mutans and S. sobrinus were isolated using Chelex-100 and primarily identified by colony morphology and biochemical characteristics. The isolates of S. mutans were genotyped using arbitrarily primed polymerase chain reaction. A total of 516 isolates of S. mutans were genotyped from 47 sites in 14 students, and 44 different genotypes were determined. All of the caries-free individuals harbored S. mutans but not S. sobrinus, although individuals 3 and 7 had no S. mutans in their saliva. The CFU value of S. mutans on carious surfaces was the highest, and values in saliva, fissures, and occlusal surfaces were higher in caries-active individuals than in caries-free individuals. We detected 28 genotypes of S. mutans in caries-free individuals, each of who carried more than 3 genotypes. However, we found only 16 genotypes of S. mutans in caries-active individuals, each of who carried no more than 3 genotypes. More genotypes are harbored in the saliva, fissures, and smooth surfaces of caries-free individuals than of caries-active individuals. The proportion of samples positive for S. mutans and S. sobrinus was significantly higher in caries-active individuals than in caries-free individuals, and the presence of these species is a risk factor for high DMFT in dental caries. Isolates of S. mutans exist that have apparent genetic diversity. The genotypes of isolates might relate to differences in caries susceptibility.
本研究旨在确定从无龋和活跃龋患者中分离出的变形链球菌（S. mutans）和远缘链球菌（S. sobrinus）的数量和分布。从 7 名 22-24 岁的无龋和 7 名活跃龋（DMFT≥6）患者中采集非刺激性唾液、右上颌牙齿颊面光滑表面、完好咬合面窝沟和龋面。使用 Chelex-100 分离 S. mutans 和 S. sobrinus，并通过菌落形态和生化特征初步鉴定。使用随机引物聚合酶链反应对 S. mutans 分离株进行基因分型。从 14 名学生的 47 个部位共分离出 516 株 S. mutans 进行基因分型，确定了 44 种不同的基因型。所有无龋个体均携带 S. mutans，但不携带 S. sobrinus，尽管个体 3 和 7 的唾液中没有 S. mutans。龋面 S. mutans 的 CFU 值最高，活跃龋个体的唾液、窝沟和咬合面的 S. mutans CFU 值均高于无龋个体。我们在无龋个体中检测到 28 种 S. mutans 基因型，每个个体携带超过 3 种基因型。然而，在活跃龋个体中仅发现 16 种 S. mutans 基因型，每个个体携带不超过 3 种基因型。无龋个体的唾液、窝沟和光滑表面携带的基因型多于活跃龋个体。活跃龋个体中 S. mutans 和 S. sobrinus 阳性样本的比例明显高于无龋个体，这些物种的存在是龋齿 DMFT 高的危险因素。S. mutans 分离株存在明显的遗传多样性。分离株的基因型可能与龋易感性的差异有关。
