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Comparative Study
. 2015 Aug;41(8):1226-33.
doi: 10.1016/j.joen.2015.03.010. Epub 2015 Apr 21.

Comparison of Bacterial Community Composition of Primary and Persistent Endodontic Infections Using Pyrosequencing

Giorgos N Tzanetakis  1 , M Andrea Azcarate-Peril  2 , Sophia Zachaki  3 , Panos Panopoulos  4 , Evangelos G Kontakiotis  4 , Phoebus N Madianos  5 , Kimon Divaris  6
Affiliations
Comparative Study

Comparison of Bacterial Community Composition of Primary and Persistent Endodontic Infections Using Pyrosequencing

Giorgos N Tzanetakis et al. J Endod. 2015 Aug.

Abstract

Introduction: Elucidating the microbial ecology of endodontic infections (EIs) is a necessary step in developing effective intracanal antimicrobials. The aim of the present study was to investigate the bacterial composition of symptomatic and asymptomatic primary and persistent infections in a Greek population using high-throughput sequencing methods.

Methods: 16S amplicon pyrosequencing of 48 root canal bacterial samples was conducted, and sequencing data were analyzed using an oral microbiome-specific and a generic (Greengenes) database. Bacterial abundance and diversity were examined by EI type (primary or persistent), and statistical analysis was performed by using non-parametric and parametric tests accounting for clustered data.

Results: Bacteroidetes was the most abundant phylum in both infection groups. Significant, albeit weak associations of bacterial diversity were found, as measured by UniFrac distances with infection type (analyses of similarity, R = 0.087, P = .005) and symptoms (analyses of similarity, R = 0.055, P = .047). Persistent infections were significantly enriched for Proteobacteria and Tenericutes compared with primary ones; at the genus level, significant differences were noted for 14 taxa, including increased enrichment of persistent infections for Lactobacillus, Streptococcus, and Sphingomonas. More but less abundant phyla were identified using the Greengenes database; among those, Cyanobacteria (0.018%) and Acidobacteria (0.007%) were significantly enriched among persistent infections. Persistent infections showed higher phylogenetic diversity (PD) (asymptomatic: PD = 9.2, standard error [SE] = 1.3; symptomatic: PD = 8.2, SE = 0.7) compared with primary infections (asymptomatic: PD = 5.9, SE = 0.8; symptomatic: PD = 7.4, SE = 1.0).

Conclusions: The present study revealed a high bacterial diversity of EI and suggests that persistent infections may have more diverse bacterial communities than primary infections.

Keywords: Bacterial diversity; oral microbiome; persistent infection; primary endodontic infection; pyrosequencing.

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Conflict of interest statement

The authors deny any conflicts of interest related to this study.

No other potential conflict of interest is disclosed.

Figures

Figure 1
Figure 1
Rarefaction curves illustrating the number of observed species-level OTUs and 95% confidence limits according to database and sampling depth. Panel A: Human Oral Microbiome Database (HOMD) and panel B: Greengenes database
Figure 2
Figure 2
Abundance of observed phyla with relative abundance of ≥0.5% in the entire sample (panel A) and according to endodontic infection type (panel B)
Figure 3
Figure 3
Abundance of most abundant observed genera (≥1%) among the entire sample (panel A) and according to endodontic infection type (panel B)
Figure 4
Figure 4
Measures of bacterial diversity (Phylogenetic Diversity index, top panel; Shannon index, bottom panel) according to endodontic infection type and presence of symptoms
See this image and copyright information in PMC

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