An improved method for detecting mutans streptococci using a commercial kit.

The improved detection of mutans streptococci (MS) in individuals was investigated using several modifications to a commercially available kit, Dentocult SM. Significantly better detection of MS was achieved using plaque from the four approximal surfaces at two interdental spaces than with saliva (P < 0.001). Furthermore, the MS estimates for approximal surfaces at the same interdental space were similar (kappa = 0.654) suggesting that differentiating the two surfaces does not improve the detection of MS, and that increasing the number of interdental spaces sampled is a more effective option. This study also evaluated a modification to the standard Dentocult SM site strip method in which two strips were incubated per broth vial so that plaque from eight interdental spaces could be tested at the same time (new method). The results were compared to those obtained when one strip was incubated per broth vial (standard method). Although the MS estimates by the new and standard methods were comparable (kappa = 0.721), the efficiency of MS detection was improved significantly by increasing the number of sites used for MS estimates (P = 0.01). In conclusion, MS detection at eight interdental spaces is recommended using the new Dentocult SM method.