RAPID CHAIR-SIDE DNA-PROBE ASSAY OF BACTEROIDES-FORSYTHUS AND PORPHYROMONAS-GINGIVALIS

This study compared a rapid, colorimetric DNA probe assay designed to be performed in a dental office within 40 min, with anaerobic culture and indirect immunofluorescence microscopy (IFM) for detection of Bact eroides forsythus and Porphyromonas gingivalis in subgingival plaque s amples. The DNA probe assay used the Periodontal Microbial Identificat ion Test (Saigene Corporation, Bothell, Washington, USA). B. forsythus was detected in 46 (52%), 49 (55%) and 39 (44%) of the samples by DNA probe, culture (at levels greater than or equal to 10(5)) and IFM, re spectively. P. gingivalis was detected in 24 (27%), 18 (20%) and 29 (3 3%) of the samples by DNA probe, culture (at levels greater than or eq ual to 10(5)) and IFM, respectively. Results from the DNA probe assay were compared to culture. Culture negative, probe positive samples wer e re-evaluated by IFM, and IFM positive samples were considered positi ve in ''resolved'' data. Using resolved data, DNA probe detection sens itivity and specificity values for B. forsythus were 81% and 91% and f or P. gingivalis were 80% and 95%, respectively. DNA probe test result s were further compared with culture and IFM. For samples negative by both culture and IFM, probe specificity was 92% in 25 B. forsythus sam ples and 95% in 57 P. gingivalis samples. For samples positive by both reference methods, probe sensitivity was 82% in 27 B. forsythus sampl es and 73% in 15 P. gingivalis samples. B. forsythus was detected more frequently by culture compared with IFM; the reverse was observed for P. gingivalis. The rapid DNA probe assay for B. forsythus and P. ging ivalis was comparable to cultivable and IF analyses.