[Comparative study of five different methods for grouping beta-haemolytic streptococci (author's transl)].

Abstract

161 strains of beta-haemolytic streptococci, that had been isolated from patients' material, and 7 reference strains were group]ed with the techniques of precipitation, direct immunofluorescence, co-agglutination (Phadebact Streptococcus Test), latex agglutination (Streptex), and biochemical tests (Api-Strep). From the reference strains one group G strain was incorrectly identified with the Api-Strep. The direct immunofluorescence test yielded a result in agreement with the precipitation method in 94% of the freshly isolated strains. Co-agglutination and latex agglutination gave corresponding results with the precipitation method in 99%, taking into consideration that the first method doesn't apply to groups D and F. The biochemical determination with Api-Strep gave correct results with all strains of groups A and B, but did not do so with some group G and most of the group C streptococcal strains. Therefore especially co-agglutination and latex agglutination can be recommended for routine diagnostic purposes as reliable, rapid, and simple methods.