Mattos-Graner R O, Smith D J, King W F, Mayer M P
Department of Pediatric Dentistry, Faculty of Odontology of São Paulo, Brazil.
J Dent Res. 2000 Jun;79(6):1371-7. doi: 10.1177/00220345000790060401.
Early mutans streptococci (MS) infection has been associated with higher caries activity in childhood. Since colonization with MS does not always lead to caries activity, additional factors may be involved in MS cariogenicity. For example, MS may differ in virulence traits such as the potential to synthesize glucan polymers from sucrose. In the present study, we tested the hypothesis that caries activity can be associated with variations in virulence factor expression of MS-infecting strains. At baseline, levels of MS obtained by the tongue-blade sampling method, and the presence of visible plaque on upper incisors, were measured in 101 12- to 30-month-old children. Dental caries lesions were diagnosed at baseline and after one year. Caries incidence data were then used to select ten caries-free and nine caries-active children from whom a total of 20 MS fresh isolates was studied. Water-insoluble glucan (WIG) synthesis, final pH, and sucrose-dependent adherence on glass surfaces were measured in these MS isolates. Concentrated culture supernatants were separated in duplicate SDS-PAGE gels, which were then either stained for protein or incubated with 5% sucrose. The intensities of the WIG bands developed in the 5% sucrose PAGE gels and the corresponding protein-stained GTF bands were measured by scanning densitometry. High MS levels (> or = 100 CFU) were associated with high caries incidence (p < 0.01). The presence of visible plaque did not correlate with caries incidence. The intensities of WIG bands were positively correlated with caries incidence (p < 0.05) and with the ability of MS to adhere to glass surfaces (p < 0.05). Analysis of our data suggests that the ability to synthesize WIG is an important virulence factor in initial caries development by increasing MS adherence and accumulation in the plaque of young children.
早期变形链球菌（MS）感染与儿童期较高的龋齿活性有关。由于MS定植并不总是导致龋齿活性，其他因素可能参与了MS的致龋性。例如，MS在毒力特性方面可能存在差异，如从蔗糖合成葡聚糖聚合物的潜力。在本研究中，我们检验了龋齿活性可能与感染MS的菌株毒力因子表达变化相关的假设。在基线时，对101名12至30个月大的儿童采用舌片采样法测量MS水平，并检查上颌切牙上可见菌斑的存在情况。在基线时和一年后诊断龋齿病变。然后利用龋齿发病率数据从10名无龋儿童和9名患龋儿童中选取了共20株MS新鲜分离株进行研究。对这些MS分离株测量了水不溶性葡聚糖（WIG）合成、最终pH值以及在玻璃表面的蔗糖依赖性黏附。将浓缩的培养上清液在两份SDS-PAGE凝胶中进行分离，然后一份进行蛋白质染色，另一份与5%蔗糖一起孵育。通过扫描光密度测定法测量在5%蔗糖PAGE凝胶中出现的WIG条带强度以及相应蛋白质染色的GTF条带强度。高MS水平（≥100 CFU）与高龋齿发病率相关（p < 0.01）。可见菌斑的存在与龋齿发病率无关。WIG条带强度与龋齿发病率呈正相关（p < 0.05），与MS黏附玻璃表面的能力也呈正相关（p < 0.05）。对我们数据的分析表明，合成WIG的能力是幼儿龋齿初始发展中的一个重要毒力因子，它通过增加MS在上颌切牙菌斑中的黏附和聚集来实现。
