Siqueira José Freitas, Rôças Isabela das Neves
Department of Endodontics, Estâcio de Sá University, Brazil.
Pesqui Odontol Bras. 2003 Apr-Jun;17(2):142-6. doi: 10.1590/s1517-74912003000200008. Epub 2003 Oct 10.
The aim of this study was to describe a 16S rDNA-based nested polymerase chain reaction (nPCR) assay to investigate the occurrence of Campylobacter gracilis in oral infections. Samples were collected from ten infected root canals, ten cases of acute periradicular abscesses and eight cases of adult marginal periodontitis. DNA extracted from the samples was initially amplified using universal 16S rDNA primers. A second round of amplification used the first PCR products to detect C. gracilis using oligonucleotide primers designed from species-specific 16S rDNA signature sequences. The nPCR assay used in this study showed a detection limit of 10 C. gracilis cells and no cross-reactivity was observed with nontarget bacteria. C. gracilis was detected in the three types of oral infections investigated - 4/10 infected root canals; 2/10 acute periradicular abscesses; and 1/8 subgingival specimens from adult periodontitis. The method proposed in this study showed both high sensitivity and high specificity to directly detect C. gracilis in samples from root canal infections, abscesses, and subgingival plaque. Our findings confirmed that C. gracilis may be a member of the microbiota associated with distinct oral infections, and its specific role in such diseases requires further clarification.
本研究的目的是描述一种基于16S rDNA的巢式聚合酶链反应（nPCR）检测方法，以调查纤细弯曲菌在口腔感染中的发生情况。从10个感染根管、10例急性根尖周脓肿和8例成人边缘性牙周炎患者中采集样本。从样本中提取的DNA最初使用通用16S rDNA引物进行扩增。第二轮扩增使用第一轮PCR产物，使用根据物种特异性16S rDNA特征序列设计的寡核苷酸引物检测纤细弯曲菌。本研究中使用的nPCR检测方法的检测限为10个纤细弯曲菌细胞，未观察到与非靶细菌的交叉反应。在调查的三种口腔感染类型中检测到了纤细弯曲菌——10个感染根管中有4个；10例急性根尖周脓肿中有2例；8例成人牙周炎龈下标本中有1例。本研究中提出的方法对直接检测根管感染、脓肿和龈下菌斑样本中的纤细弯曲菌具有高灵敏度和高特异性。我们的研究结果证实，纤细弯曲菌可能是与不同口腔感染相关的微生物群的成员，其在这些疾病中的具体作用需要进一步阐明。
