Novel and conventional assays in determining abundance of Streptococcus mutans in saliva

Background: Effective caries control and management requires identification of susceptible children for timely intervention. Streptococcus mutans (S. mutans) is an important biomarker of caries risk.

Aim: This study aimed to comparatively evaluate the validities of a novel immunoassay and a conventional culture-based assay in detecting salivary S. mutans in a paediatric cohort.

Methods: 190 children aged 3-4 years were recruited. The abundance of S. mutans in their saliva samples was analysed with three assay systems viz. a conventional culture-based assay (Dentocult SM), a novel immunoassay system (Saliva-Check MUTANS) based on monoclonal antibody technology and a Taqman real-time PCR assay taken as a gold standard.

Results: The novel immunoassay accurately differentiated saliva samples with high (≥5 × 10(5) CFU/mL) and low (<5 × 10(5) CFU/mL) S. mutans levels. The sensitivity/specificity was 97.6%/90.6%. The conventional culture-based assay reached a reasonably high sensitivity/specificity (92.8%/81.3%) in identifying children with moderate (≥10(4) CFU/mL) S. mutans level. Its sensitivity/ specificity in selecting children with high (≥10(5) CFU/mL) and very high (>10(6) CFU/mL) S. mutans levels were not sufficient (78.7%/79.8% and 25.8%/91.8%, respectively).

Conclusion: The monoclonal antibody-based immunoassay accurately and rapidly determines S. mutans abundance in saliva and could be useful for chairside assessment of children's caries risk.