1985 Volume 59 Issue 12 Pages 1204-1209
It has been well known that C-polysaccharide antigen of group A streptococci is extracted by nitrous acid and the agglutinating reaction is observed between this antigen and anti-C-polysaccharide antibody coated latex particles.Recently, a latex agglutination kit (Culturette Brand Ten-Minute Group A Strep ID) for the identification of group A streptococci directly from throat swabs was developed as a useful and highly rapid technique for the application of clinical use.
The purpose of this investigation was to evaluate this kit in regard to its specificity and sensitivity.
The results obtained were as follows:
1) The agglutinating reactions appeared by using 10-1 to 10-6 diluted fluids of the original group A streptococcal cell suspension (1.4×108 cells/ml) and latex particles coating anti-group A Cpolysaccharide antibody, but the positive reaction was not observed by employing 10-7 diluted fluid of the cells.
2) Group A streptococcal cell suspension only reacted with latex particles coating anti-group A St. C-polysaccharide antibody, but group B St., group C St., group D St., group G St., St.pneumoniae, St. sanguis, St.mitior, St.mutans, S.aureus and S.epidermidis did not react with the latex particles.
3) Identification of group A St.by Strep ID test was not affected by the existence of various bacterial strains.
4) The latex particles coating anti-group A St.C-polysaccharide antibody reacted with group A St. C-polysaccharide (50ng/ml), but it did not react with C-polysaccharide of St.pneumoniae and Protein-A.
5) The reaction of strep ID test was inhibited by the addition of N-acetyl-glucosamine.
Therefore, the Strep ID test is considered to be a sensitive and specific tool to identify group A St.
