Direct detection of Porphyromonas gingivalis in Macaca fascicularis dental plaque samples using an oligonucleotide...

Oligonucleotide probes complementary to the hypervariable regions of the 16S rRNA of Porphyromonas gingivalis, and previously shown to specifically identify human P. gingivalis strains to the species level, were tested for their ability to recognize P. gingivalis from nonhuman primates (Macaca fascicularis), either as distinct isolates or in subgingival dental plaque. The 32P-labeled probes hybridized with all 147 monkey isolates identified as P. gingivalis by morphology and biochemistry, but did not hybridize with any of the 331 isolates representing 17 genera of bacteria unrelated to P. gingivalis, or to the more closely related P. endodontalis and P. asaccharolytica. This corresponds to sensitivities and specificities of 100%. Of 76 M. fascicularis plaque samples, P. gingivalis was detected by probe and culture in 67. Of 26 human plaque samples taken from separate individuals free of periodontal disease, 23 failed to demonstrate P. gingivalis by probe or culture. The results of the combined 102 monkey and human plaque samples indicate that, when compared to culture as the "gold standard," the P. gingivalis probe had a sensitivity of 96%, a specificity of 87%, and an overall agreement with culture of 93%. These results reveal that the oligonucleotide probes used to identify P. gingivalis are specific for this organism, and give results comparable to culture methods for detecting the presence of P. gingivalis in M. fascicularis dental plaque.