Bacterial diversity of symptomatic primary endodontic infection by clonal analysis

Letícia Maria Menezes NÓBREGA,Francisco MONTAGNER,Adriana Costa RIBEIRO,Brenda Paula Figueiredo de Almeida GOMES,Márcia Alves Pinto MAYER

doi:10.1590/1807-3107bor-2016.vol30.0103

Abstract

The aim of this study was to explore the bacterial diversity of 10 root canals with acute apical abscess using clonal analysis. Samples were collected from 10 patients and submitted to bacterial DNA isolation, 16S rRNA gene amplification, cloning, and sequencing. A bacterial genomic library was constructed and bacterial diversity was estimated. The mean number of taxa per canal was 15, ranging from 11 to 21. A total of 689 clones were analyzed and 76 phylotypes identified, of which 47 (61.84%) were different species and 29 (38.15%) were taxa reported as yet-uncultivable or as yet-uncharacterized species. Prevotella spp., Fusobacterium nucleatum, Filifactor alocis, and Peptostreptococcus stomatis were the most frequently detected species, followed by Dialister invisus, Phocaeicola abscessus, the uncharacterized Lachnospiraceae oral clone, Porphyromonas spp., and Parvimonas micra. Eight phyla were detected and the most frequently identified taxa belonged to the phylum Firmicutes (43.5%), followed by Bacteroidetes (22.5%) and Proteobacteria (13.2%). No species was detected in all studied samples and some species were identified in only one case. It was concluded that acute primary endodontic infection is characterized by wide bacterial diversity and a high intersubject variability was observed. Anaerobic Gram-negative bacteria belonging to the phylum Firmicutes, followed by Bacteroidetes, were the most frequently detected microorganisms.

Highlights

Acute endodontic infections are one of the most frequently treated conditions in emergency endodontic procedures
Direct amplification of 16S rDNA genes from DNA extracted from bacteria in clinical samples, followed by cloning and sequencing of the genes, has allowed bacterial communities to be characterized in their entirety, without the biases of culture-based studies.[8]
Assessment of the human oral microbiome using metagenomic approaches, with genetic material recovered from oral cavity samples, has revealed that these techniques are sensitive and precise for evaluation of bacterial diversity in root canal infections, allowing the identification of some unexpected pathogens or those not often associated with endodontic infection.[11,15,16,17]

Summary

Introduction

Acute endodontic infections are one of the most frequently treated conditions in emergency endodontic procedures. These infections are characterized by spontaneous pain, tenderness to percussion, and pain on palpation. Microorganisms might reach the apical connective tissues, leading to an intense inflammatory response.[1,2] If untreated, these infections might progress resulting in life-threatening conditions and systemic complications. The microbiota associated with acute endodontic infections is highly heterogeneous, presenting different bacterial profiles among the patients.[1] Elucidating the microbial ecology of endodontic infections is a necessary step in understanding the necessity of microbial control during all phases of endodontic treatment.[3]

Objectives

Methods

Results

Conclusion