Nakano Kazuhiko, Nomura Ryota, Shimizu Noriko, Nakagawa Ichiro, Hamada Shigeyuki, Ooshima Takashi
Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, 1-8 Yamada-oka, Suita, Osaka 565-0871, Japan.
J Clin Microbiol. 2004 Nov;42(11):4925-30. doi: 10.1128/JCM.42.11.4925-4930.2004.
In a previous study, we isolated and characterized a new serotype k of Streptococcus mutans from human blood and oral cavities. Analysis of the genes involved in biosynthesis of the serotype-specific polysaccharide of serotype k strains revealed that the serotype k-specific nucleotide alignment was commonly present in the 5' region of the rgpF gene (350 bp from the initial sequence) compared to the reference strains, and then a method for rapid identification of serotype k strains was developed by use of PCR with primers designed on the basis of the sequence of the variable region. PCR assays with primers specific for amplification of serotype k strains showed a negative reaction with serotype c, e, and f strains and a positive reaction with serotype k strains, with the sensitivity for identification of the serotype k strains shown to range from 5 to 50 cells. Next, the frequency of positive reactions for serotype k-specific primers was surveyed with DNA taken from saliva samples from 200 subjects (2 to 18 years of age), and 10 of those showed a positive reaction, which was higher than the frequency in our previous survey with a serological method. In addition, all saliva samples from subjects with serotype k strains in our previous study were shown to be positive with the serotype k-specific primers. These results indicate that this new PCR method is effective for identification of subjects with S. mutans serotype k.
在之前的一项研究中，我们从人血液和口腔中分离并鉴定了一种变形链球菌的新血清型k。对血清型k菌株血清型特异性多糖生物合成相关基因的分析表明，与参考菌株相比，血清型k特异性核苷酸序列通常存在于rgpF基因的5'区域（距起始序列350 bp），然后基于可变区序列设计引物，通过PCR开发了一种快速鉴定血清型k菌株的方法。用特异性扩增血清型k菌株的引物进行PCR检测，结果显示与血清型c、e和f菌株呈阴性反应，与血清型k菌株呈阳性反应，血清型k菌株鉴定的灵敏度为5至50个细胞。接下来，用来自200名受试者（2至18岁）唾液样本的DNA检测血清型k特异性引物的阳性反应频率，其中10人呈阳性反应，高于我们之前用血清学方法进行的调查频率。此外，在我们之前的研究中，所有携带血清型k菌株受试者的唾液样本用血清型k特异性引物检测均呈阳性。这些结果表明，这种新的PCR方法对于鉴定变形链球菌血清型k的受试者是有效的。
