Department of Pediatric Dentistry, Oregon Health & Science University (OHSU) School of Dentistry, Portland, OR.
J Oral Microbiol. 2012;4. doi: 10.3402/jom.v4i0.19530. Epub 2012 Dec 14.
Genotypic strains of cariogenic mutans streptococci (MS) may vary in important virulence properties. In previous published studies, we identified 39 MS strains from pediatric patients undergoing full-mouth dental rehabilitation, including the removal and/or repair of carious lesions and application of antimicrobial rinse and fluoride varnish.
The objectives of this current 1-year follow-up study are to assess the variability of MS strains that occur at 1-year post-rehabilitation and characterize the xylitol-resistance properties of MS strains that predominate.
Plaque from five children with severe early childhood caries was collected 1-year post-rehabilitation. MS isolates were subjected to arbitrarily primed-polymerase chain reaction (AP-PCR) for identification of genetic strains and in vitro xylitol-inhibition experiments. To more precisely define strain distributions within each patient, we isolated large numbers of isolates per patient.
MS strains diminished from several strains pre-rehabilitation, to one dominant strain at 1-year post-rehabilitation, with several new emergent strains. The majority of the clinical MS strains, as well as the Streptococcus mutans laboratory strains ATCC 25175 and 35668, were predicted to undergo 50% inhibition with 2.48-5.58% xylitol, with some clinical MS strains being significantly more resistant in vitro.
Our follow-up study using patients from the original cohort demonstrates that specific MS strains are dominant at 1-year post-dental rehabilitation. Most of the clinical MS strains are similar in xylitol resistance to the attenuated S. mutans ATCC control strains, with some strains being more resistant to xylitol in vitro.
致龋变形链球菌（MS）的基因型菌株在重要的毒力特性上可能存在差异。在之前发表的研究中，我们从接受全口牙齿康复治疗的儿科患者中鉴定了 39 株 MS 菌株，包括龋齿病变的去除和/或修复以及使用抗菌漱口水和氟化物漆。
本当前为期 1 年的随访研究的目的是评估康复后 1 年 MS 菌株的变异性，并表征占优势的 MS 菌株的木糖醇耐药特性。
在康复后 1 年，从 5 名患有严重幼儿期龋齿的儿童的菌斑中采集 MS 分离物。对 MS 分离物进行随机引物聚合酶链反应（AP-PCR）鉴定遗传菌株，并进行体外木糖醇抑制实验。为了更精确地定义每个患者内的菌株分布，我们从每个患者中分离出大量的分离物。
MS 菌株从康复前的几个菌株减少到康复后 1 年的一个优势菌株，并出现了几个新的出现的菌株。大多数临床 MS 菌株，以及口腔变形链球菌实验室菌株 ATCC 25175 和 35668，预计在 2.48%-5.58%的木糖醇浓度下会发生 50%的抑制，一些临床 MS 菌株在体外表现出明显更高的耐药性。
我们使用原始队列中的患者进行的随访研究表明，特定的 MS 菌株在牙齿康复后 1 年占优势。大多数临床 MS 菌株对木糖醇的耐药性与衰减的 S. mutans ATCC 对照菌株相似，一些菌株在体外对木糖醇的耐药性更强。
