Validation of a multiplex qPCR assay for detection and quantification of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Tannerella forsythia in subgingival plaque samples. A comparison with anaerobic culture.

OBJECTIVE: To validate a multiplex real time qPCR (m-qPCR) assay for the simultaneous detection and quantification of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Tannerella forsythia in subgingival samples, when compared with anaerobic culture. MATERIAL AND METHODS: Subgingival plaque samples were obtained from patients seeking periodontal treatment. Samples were processed in parallel by anaerobic culturing and by m-qPCR directed to the target bacterial species. Counts and frequency of detection were calculated and analyzed by Mann-Whitney U and chi-square tests, respectively. Contingency tables were constructed, and sensitivity, specificity, predictive values and Lin's correlation coefficients were calculated. RESULTS: Fifty-nine samples were included in the study. A good concordance was achieved between m-qPCR and culture for A. actinomycetemcomitans and P. gingivalis (net agreement, 94.92% and 91.53%, respectively). For T. forsythia, m-qPCR showed statistically significant higher counts than culture (p < 0.005), and low specificity (3.12%) and concordance (47.46%). High sensitivity (above 96.22%) was attained for the three target bacteria with m-qPCR. CONCLUSION: Compared to culture, the tested m-qPCR assay for subgingival plaque samples showed high degree of sensitivity in the simultaneous quantification of A. actinomycetemcomitans, P. gingivalis and T. forsythia.