Evaluation of slide agglutination methods for identifying group D streptococci

Abstract

Three commercial reagents for the rapid identification of group D streptococci by slide agglutination were evaluated. These included SeroSTAT (Scott Laboratories, Fiskeville, R.I.), Streptex (Wellcome Laboratories, Research Triangle Park, N.C.), and Phadebact (Pharmacia Diagnostics, Piscataway, N.J.). The methods included direct colony testing, enzyme extraction with pronase, and broth culture. A total of 72 strains of group D streptococci were tested. The SeroSTAT and Streptex reagents with pronase extraction each identified 65 (90%) of the strains. The SeroSTAT reagent was somewhat more specific since it did not cross-react with other streptococci of the viridans group. The Phadebact reagent was nonreactive. We conclude that the latex reagents can be very useful for the quick recognition of group D streptococci in the clinical laboratory.