Qin Xiu-rong, Zhou Qiong, Qin Man
Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology, Beijing 100081, China.
Zhonghua Kou Qiang Yi Xue Za Zhi. 2009 Jun;44(6):347-50.
To evaluate the genotypic diversity of Streptococcus sobrinus (Ss) between children suffering with severe early childhood caries (S-ECC) and caries-free children by arbitrarily primed-polymerase chain reaction (AP-PCR).
A total of 178 children aged from 42 to 54 months were recruited from 14 urban kindergartens. The S-ECC group contained 87 children with more than 5 decayed teeth, and the control group was composed of 91 caries-free children. Stimulated whole saliva was collected by chewing paraffin. All mutans streptococcus isolates were subcultured, biochemically characterised and identified by PCR as Streptococcus mutans (Sm) and Ss. Then the Ss isolates were genotyped by AP-PCR.
The frequency of Ss detection was 18% in S-ECC children, which was significantly higher than 3% in caries-free children (P < 0.01). Twenty-two distinct genotypes of Ss were identified from 53 clinical isolates. In S-ECC group, one to three genotypes of Ss were detected in each saliva sample. Only one genotype of Ss was detected in all the caries-free children. One genotype of Ss were shared by three S-ECC children. The genotypes of isolates in S-ECC group were relate to decayed-missing-filled teeth (r = 0.50, P < 0. 05).
The rate of Ss detection was significantly higher in S-ECC children than in caries-free children. Isolates of Ss displayed genetic polymorphism. The multi-genotypes of Ss was related to differences in caries susceptibility. Strains of Ss with same genotype were present in unrelated subjects.
通过任意引物聚合酶链反应（AP-PCR）评估重度幼儿早期龋（S-ECC）患儿和无龋患儿之间远缘链球菌（Ss）的基因型多样性。
从14所城市幼儿园招募了178名年龄在42至54个月的儿童。S-ECC组包括87名患龋牙数超过5颗的儿童，对照组由91名无龋儿童组成。通过咀嚼石蜡收集刺激全唾液。所有变形链球菌分离株进行传代培养，通过生化特性鉴定，并通过PCR鉴定为变形链球菌（Sm）和Ss。然后通过AP-PCR对Ss分离株进行基因分型。
S-ECC患儿中Ss的检出率为18%，显著高于无龋患儿中的3%（P<0.01）。从53株临床分离株中鉴定出22种不同的Ss基因型。在S-ECC组中，每个唾液样本中检测到1至3种Ss基因型。在所有无龋儿童中仅检测到1种Ss基因型。3名S-ECC患儿共享1种Ss基因型。S-ECC组分离株的基因型与龋失补牙数相关（r = 0.50，P<0.05）。
S-ECC患儿中Ss的检出率显著高于无龋患儿。Ss分离株表现出遗传多态性。Ss的多种基因型与龋易感性差异有关。具有相同基因型的Ss菌株存在于无亲缘关系的个体中。
