Nóbrega Letícia M M, Montagner Francisco, Ribeiro Adriana C, Mayer Márcia A P, Gomes Brenda P F A
Department of Restorative Dentistry, Endodontics Division, Piracicaba Dental School, UNICAMP - Universidade Estadual de Campinas, Piracicaba, SP, Brazil, Universidade Estadual de Campinas, Universidade Estadual de Campinas, Piracicaba SP , Brazil.
Department of Conservative Dentistry, Endodontics Division, UFRGS - Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil, Universidade Federal do Rio Grande do Sul, Universidade Federal do Rio Grande do Sul, Porto Alegre RS , Brazil.
Braz Dent J. 2016 May-Jun;27(3):318-24. doi: 10.1590/0103-6440201600715.
The objective of this study was to investigate the bacterial composition present in root canals of teeth associated with acute apical abscess by molecular identification (16S rRNA) of cultivable bacteria. Two hundred and twenty strains isolated by culture from 20 root canals were subjected to DNA extraction and amplification of the 16S rRNA gene (PCR), followed by sequencing. The resulting nucleotide sequences were compared to the GenBank database from the National Center of Biotechnology Information through BLAST. Strains not identified by sequencing were submitted to clonal analysis. The association of microbiological findings with clinical features and the association between microbial species were also investigated. Fifty-nine different cultivable bacteria were identified by 16S rRNA gene sequencing, belonging to 6 phyla, with an average number of 6 species per root canal. Molecular approaches allowed identification of 99% of isolates. The most frequently identified bacteria were Prevotella spp., Pseudoramibacter alactolyticus, Parvimonas micra, Dialister invisus, Filifactor alocis, and Peptostreptococcus stomatis. Positive association was found between Prevotella buccae and Pseudoramibacter alactolyticus and between Parvimonas micra and Prevotella nigrescens (both p<0.05). It was concluded that the microbiota of infected root canals associated with acute apical abscess is diverse and heterogeneous, composed mainly of anaerobic Gram-negative bacteria, with the great majority belonging to the phyla Firmicutes and Bacteroidetes.
本研究的目的是通过对可培养细菌进行分子鉴定（16S rRNA），调查与急性根尖脓肿相关牙齿根管内的细菌组成。从20个根管中培养分离出的220株菌株进行DNA提取和16S rRNA基因的扩增（PCR），随后进行测序。将所得核苷酸序列通过BLAST与美国国立生物技术信息中心的GenBank数据库进行比较。未通过测序鉴定的菌株进行克隆分析。还研究了微生物学结果与临床特征的关联以及微生物物种之间的关联。通过16S rRNA基因测序鉴定出59种不同的可培养细菌，属于6个门，每个根管平均有6个物种。分子方法能够鉴定出99%的分离株。最常鉴定出的细菌是普雷沃菌属、解糖假拉米菌、微小单胞菌、隐匿戴阿利斯特菌、栖瘤胃普雷沃菌和口腔消化链球菌。发现颊普雷沃菌和解糖假拉米菌之间以及微小单胞菌和变黑普雷沃菌之间存在正相关（两者p<0.05）。得出的结论是，与急性根尖脓肿相关的感染根管内的微生物群是多样且异质的，主要由厌氧革兰氏阴性菌组成，绝大多数属于厚壁菌门和拟杆菌门。
