Rapid Chair-Side Test for Detection of Porphyromonas gingivalis

Abstract

Porphyromonas gingivalis is a keystone pathogen of chronic periodontitis, and its intraoral levels have been shown to predict disease progression (activity). An accurate and sensitive chair-side (point of care) test to determine disease activity is critical for early intervention and clinical management of disease. This study aimed to develop a rapid, chair-side, saliva-based detection of P. gingivalis. Monoclonal antibodies (mAbs) to the A1-adhesin domain of the P. gingivalis RgpA-Kgp proteinase-adhesin complex were screened by enzyme-linked immunosorbent assay and microbial flow cytometry, with 2 mAbs shown to recognize all laboratory and clinical strains tested, without significantly cross-reacting with other oral bacteria tested. With these mAbs, an immunochromatographic device was produced and shown in preclinical studies to detect, in inoculated saliva, all P. gingivalis laboratory strains and clinical isolates tested. The device was able to detect ≥1 × 10⁵ P. gingivalis cells/mL. In a patient age- and sex-matched control clinical cohort, P. gingivalis levels in saliva—as measured by real-time polymerase chain reaction—positively correlated with P. gingivalis levels in subgingival plaque (r = 0.819, P < 0.01) and clinical parameters of disease (r = 0.633, P < 0.01). A positive device result strongly correlated with P. gingivalis levels >1 × 10⁵ cells/mL in saliva (r = 0.778, P < 0.001) and subgingival plaque (r = 0.715, P < 0.001) with sensitivity, specificity, positive/negative predictive values, and accuracy levels of 95.0%, 93.3%, 90.5%, 96.6%, and 94.0%, respectively. The device result also positively correlated (r = 0.695, P < 0.01) with disease severity as measured by probing depth. Detection of P. gingivalis in saliva was found to be rapid, taking 3 min from sample collection.