Molecular methods now make it possible to more accurately quantitate bacteria, and allow the determination of levels of suspected periodontal pathogens. Recent studies have identified Filifactor alocis as a candidate periodontal pathogen, and Porphyromonas gingivalis and Tanerella forsythenis (formerly B. forsythus) have long been suspected to play a role in disease. Objectives: The aim of this study was to measure the levels of P. gingivalis (Pg) , T. forsythenis (Tf) , and F. alocis (Fa) as well as total bacterial cells in samples obtained from periodontal pockets and compare them to periodontally healthy control sites in the same subject. Methods: Pooled samples from 4 healthy sites and from 4 periodontal pockets were collected from 38 subjects with moderate to severe periodontitis using paper points. Real-time PCR with species-specific primers and fluorescently labeled probes were used to quantitate Pg, Tf and Fa levels directly from each sample without cultivation. A universal bacterial probe and primer set was also used to measure total bacterial cells. The target of this assay was the 16S rDNA gene and the adjacent intergenic spacer region. Real time fluorescence was measured using an iCycler with fluorescence detector (BioRad). Levels of Pg, Tf and Fa in each sample were expressed as a percentage of total bacteria. Results: No significant differences were found in percent Pg or Tf between control sites and periodontal pockets by the nonparametric, paired Wilcoxon signed rank test (P=0.47, P=0.95). In contrast, Fa levels were significantly higher in deep sites as compared to healthy sites in the same individual. Conclusions: These data provide a quantitative measure of Pg, Tf and Fa relative to total bacteria. Comparison of levels in healthy and deep sites shows a strong relationship to disease for Fa but not for Pg or Tf. Supported by DE 10467.

Back to the Microbiology / Immunology and Infection Control Program
Back to the IADR/AADR/CADR 82nd General Session (March 10-13, 2004)

Top Level Search