Bezerra Daniela S, Stipp Rafael N, Neves Beatriz G, Guedes Sarah F F, Nascimento Marcelle M, Rodrigues Lidiany K A
Postgraduation Program, Faculty of Pharmacy, Dentistry and Nursing, Federal University of Cearx00E1;, Fortaleza, Brazil.
Caries Res. 2016;50(3):279-87. doi: 10.1159/000445256. Epub 2016 May 3.
Streptococcus mutans is an oral bacterium considered to play a major role in the development of dental caries. This study aimed to investigate the prevalence of S. mutans in active and arrested dentine carious lesions of children with early childhood caries and to examine the expression profile of selected S. mutans genes associated with survival and virulence, within the same carious lesions. Dentine samples were collected from 29 active and 16 arrested carious lesions that were diagnosed in preschool children aged 2-5 years. Total RNA was extracted from the dentine samples, and reverse transcription quantitative real-time PCR analyses were performed for the quantification of S. mutans and for analyses of the expression of S. mutans genes associated with bacterial survival (atpD, nox, pdhA) and virulence (fabM and aguD). There was no statistically significant difference in the prevalence of S. mutans between active and arrested carious lesions. Expression of the tested genes was detected in both types of carious dentine. The pdhA (p = 0.04) and aguD (p = 0.05) genes were expressed at higher levels in arrested as compared to active lesions. Our findings revealed that S. mutans is part of the viable microbial community in active and arrested dentine carious lesions. The increase in expression of the pdhA and aguD genes in arrested lesions is likely due to the unfavourable environmental conditions for microbial growth, inherent to this type of lesions.
变形链球菌是一种口腔细菌，被认为在龋齿的发展中起主要作用。本研究旨在调查患有幼儿龋齿的儿童活动性和静止性牙本质龋损中变形链球菌的流行情况，并检测同一龋损中与生存和毒力相关的选定变形链球菌基因的表达谱。从2-5岁学龄前儿童诊断出的29个活动性龋损和16个静止性龋损中采集牙本质样本。从牙本质样本中提取总RNA，并进行逆转录定量实时PCR分析，以定量变形链球菌并分析与细菌生存（atpD、nox、pdhA）和毒力（fabM和aguD）相关的变形链球菌基因的表达。活动性龋损和静止性龋损中变形链球菌的流行率无统计学显著差异。在两种类型的龋损牙本质中均检测到了测试基因的表达。与活动性龋损相比，pdhA（p = 0.04）和aguD（p = 0.05）基因在静止性龋损中的表达水平更高。我们的研究结果表明，变形链球菌是活动性和静止性牙本质龋损中活微生物群落的一部分。pdhA和aguD基因在静止性龋损中表达增加可能是由于这类龋损固有的不利于微生物生长的环境条件所致。
