Orthodontics, Faculty of Dentistry, University of Toronto, Canada.
Microbiology, Faculty of Dentistry, University of Toronto, Canada.
Arch Oral Biol. 2020 Feb;110:104601. doi: 10.1016/j.archoralbio.2019.104601. Epub 2019 Nov 5.
Dental caries is the most common chronic infectious disease in children. Streptococcus mutans, the main cariogenic bacterial species, produces persisters, nongrowing dormant variants of regular cells associated with chronicity of diseases. We hypothesized that the recurrent nature of caries, particularly within populations with high-caries risk, is due partly to specific phenotypic features of S. mutans such as its ability to form persisters. We aimed to investigate the genotypic and phenotypic differences between the S. mutans from children with severe early-childhood caries (S-ECC) and those without caries.
S. mutans from plaque samples of caries-free (CF) and S-ECC children were tested for their ability to adapt to a lethal pH in an acid tolerance response assay. The persister levels of S. mutans isolates was quantified in both groups.
S. mutanswas identified in all 23 S-ECC but only 6 of the 21 CF subjects. In most subjects, only one dominant S. mutans genotype was detected. No statistically significant differences in the mean survival percentage of S. mutans were observed between the two groups at a lethal pH of 3.5. However, the dominant genotype within a particular S-ECC subject exhibited a higher percentage of cell survival compared to those in the CF group. In S-ECC patients, S. mutans isolates displayed a ∼15-fold higher persistence phenotype than S. mutans isolates from CF patients.
The ability of S. mutans to produce high levels of persisters may contribute to part of an individual's ability to control caries disease activity and recurrent lesions.
龋齿是儿童中最常见的慢性传染病。变形链球菌是主要的致龋细菌物种，它产生的持久性细胞是常规细胞的非生长休眠变体，与疾病的慢性有关。我们假设龋齿的反复发作，特别是在高龋风险人群中，部分原因是变形链球菌的特定表型特征，如其形成持久性细胞的能力。我们旨在研究严重婴幼儿龋（S-ECC）儿童和无龋儿童的变形链球菌的基因型和表型差异。
从无龋（CF）和 S-ECC 儿童的菌斑样本中检测变形链球菌适应酸耐受反应试验中致死 pH 值的能力。在两组中均定量测定变形链球菌分离株的持久性细胞水平。
在 23 名 S-ECC 儿童中均鉴定出变形链球菌，但在 21 名 CF 儿童中仅 6 名。在大多数受试者中，仅检测到一种优势变形链球菌基因型。在致死 pH 值为 3.5 时，两组之间变形链球菌的平均存活百分比没有统计学差异。然而，在特定 S-ECC 受试者中，优势基因型的细胞存活率高于 CF 组。在 S-ECC 患者中，变形链球菌分离株的持久性表型比 CF 患者的变形链球菌分离株高约 15 倍。
变形链球菌产生高水平持久性细胞的能力可能有助于个体控制龋齿疾病活动和复发性病变的能力的一部分。
