Diversity of endodontic microflora in patients with different clinical variables

Objectives: The purpose of this study was to determine microbial diversity in endodontic infections from patients with different clinical variables, by using specific primers for several putative endodontic pathogens, as well as a clonal analysis of 16S rDNA sequences amplified using ubiquitous bacterial primers.

Methods: Necrotic pulp specimens from 27 different patients (11 with symptomatic infections, and 8 with diabetes mellitus) were analyzed. PCR was performed with primers specific for F. nucleatum, T. forsythia, T. denticola, P. gingivalis, P. endodontalis, P. nigrescens, P. intermedia, Parvomonas micra, Streptococcus spp., and Enterococcus spp. PCR with ubiquitous 16S rDNA bacterial primers was also performed; the products were cloned and plasmid DNA from twenty clones per specimen was sequenced.

Results: Clonal analysis detected 81 different phylotypes in 33 genera or orders in 7 phyla. The most prevalent phylotypes were Pseudoramibacter alactolyticus (48%), Dialister invisus (33%) and Atopobium rimae (26%). Fusobacterium genomosp. C2 was present in three specimens all from diabetic patients (Fisher Exact test; p=0.019). There was a trend for association of A. rimae with pain (Odds ratio: 5.8; Fisher Exact test, p=0.07). Specific primers revealed that F. nucleatum was most prevalent followed by Eubacterium spp., and P. micra. The mean number of phylotypes per specimen was 6.7 by clonal analysis and 3.48 by specific primers (p<0.0001).

Conclusion: Clonal and specific analyses were complimentary in describing the microbial diversity of endodontic infections, and the association of certain organisms with clinical variables. (Supported by grant DE014476 from NIDCR)