Direct detection of Porphyromonas gingivalis in Macaca fascicularis dental plaque samples using an Oligonucleotide probe
The purpose of this study was to assess the efficacy of combined Oligonucleotide probes complementary to the hypervariable regions of 16S rRNA of P. gingivalis in detecting P. gingivalis as distinct isolate in dental plaque from Macaca fascicularis. The researchers used 18 species of Bacteroides; 12 Neisseria; 12 Campylobacter; 9 Prevotella; 4 Fusobacterium; 3 Capnocytophaga, Haemophilus, Selenomonas, and Streptococcus; 2 species of Actinomyces, Kingella, and Porphyromonas; and 1 species of Eubacteriom, Wolinella, Eikenella corrodens, A. actinomycetemcomitans, E. coil, and Peptostreptococcus micros. The study included 331 non-P. gingivalis isolates and 150 monkey isolates of P. gingivalis. The human subjects were used as controls. Subjects were healthy, having no periodontal pockets greater than 3 mm or bleeding sites. Twenty-eight M. fascicularis manifesting gingivitis or undergoing ligature induced periodontitis were the source of the monkey plaque samples and monkey P. gingivalis samples. Of each sample, .9 ml was processed for DNA probe analysis while .1 ml was serially diluted and placed in a selective media for isolation of P. gingivalis. Blood agar was used for clinical specimens. DNA probes did not hybridize with any of the non-P. gingivalis isolates or clinical isolates nor with the closely related species within the same genus (P. endodontalis, P. asaccharolytica). Only isolates from monkey reacted with these probes and did not react with P. gingivalis. P. gingivalis was detected by DNA probe and by culture in 67 of the 76 subgingival plaque samples taken from the monkeys (true +). In 3 of 76 P. gingivalis was detected by probe but not by culture (false +).Three out of 76 were positive of P. gingivalis by culture and negative by probe (false -); 3 out of 76 were negative to probe and culture (true -).
After analysis of the human subgingival plaque samples, results showed 23 true negative, 2 true positive, 1 false positive, and 0 false negative. To determine reliability of the probe as compared to cultures, the sources were combined. Sensitivity was 96%, specificity 87%, and overall agreement between culture probes 93%. Plate counts in monkeys revealed that in false negatives, organisms were present in low concentrations. Positive DNA probe results have a 95% chance of agreeing with culture, and negative test results have a 90% chance of agreeing with culture. In conclusion, the data indicated that DNA probes and immunological reagents are more reliable than the traditional culture methods in detecting periodontal pathogens. [c.c.]
Moncla, B.J., P.H. Braham, G.R. Persson, R.C. Page, and A. Weinberg, J Periodont, 65:398,1994