3. 对日本儿童和青少年的发炎牙髓标本进行幽门螺杆菌DNA的检测

J Med Microbiol. 2014 Oct 20. pii: jmm.0.079491-0. doi: 10.1099/jmm.0.079491-0. [Epub ahead of print]

Detection of Helicobacter pylori DNA in inflamed dental pulp specimens from Japanese children and adolescents.

Ogaya Y1, Nomura R2, Watanabe Y3, Nakano K1.

    口腔的幽门螺杆菌定植被人为是儿童期HP感染的一个传播途径。已有很多研究报道利用不同PCR方法检测口腔标本中幽门螺杆菌的DNA，其检出率亦不同。这些检出率的差异使口腔幽门螺杆菌感染率的评估变得复杂。在该研究中，研究者构建了一个新的PCR幽门螺杆菌检测系统，并用它来分析口腔标本。首先，研究者参照GenBank数据库中登记的48株幽门螺杆菌株的全基因组信息对常用于幽门螺杆菌检测的基因核苷酸序列进行比较。选择扩增为约为300-400 bp的片段作为候选引物组，使用每个引物组对检测系统的特异性和敏感性进行评价。选出合适的靶向尿素的五组引物，其中一个单一引物组包含在PCR体系内。系统的灵敏度合适且将每反应1-10个细胞定为检测极限。这种新的PCR系统是用来检查收集自日本儿童，青少年和年轻成年人的口腔标本的幽门螺杆菌的分布（40个发炎的牙髓组织，40份唾液样本）。PCR分析表明，在发炎的牙髓组织幽门螺杆菌的检测率是15%，而所有唾液标本中均无阳性发现。我们的新的PCR系统是检测幽门螺杆菌的可靠工具。结果显示在牙髓标本中可以检测到HP，而在唾液中为阴性。提示牙髓的根管可能是幽门螺杆菌贮存的场所。

译者点评：本文作者提出了检测牙髓中幽门螺杆菌的一种新的PCR系统。但由于PCR方法本身的局限，如何看待检测结果尚需商榷。

Abstract

The oral cavity has been implicated as a source of Helicobacter pylori infection in childhood. Various PCR methods have been used to detect H. pylori DNA in oral specimens with various detection rates reported. Such disparity in detection rates complicates the estimation of the true infectious rate of H. pylori in the oral cavity. In the present study, we constructed a novel PCR system for H. pylori detection and used it to analyze oral specimens. Firstly, the nucleotide alignments of genes commonly used for H. pylori detection were compared using complete genome information for 48 strains registered in the GenBank database. Candidate primer sets with an estimated amplification size of approximately 300-400 bp were selected, and the specificity and sensitivity of the detection system using each primer set evaluated. Five sets of primers targeting urea were considered appropriate, of which a single primer set was chosen for inclusion in the PCR system. The sensitivity of the system was considered appropriate and its detection limit established as 1-10 cells per reaction. The novel PCR system was used to examine H. pylori distribution in oral specimens (40 inflamed pulp tissues, 40 saliva samples) collected from Japanese children, adolescents, and young adults. PCR analysis revealed that the detection rate of H. pylori in inflamed pulp was 15%, whereas no positive reaction was found in any of the saliva specimens. Taken together, our novel PCR system was found to be reliable for detecting H. pylori. The results obtained showed that H. pylori was detected in inflamed pulp but not saliva specimens, indicating that an infected root canal may be a reservoir for H. pylori.