Rapid grouping of beta-hemolytic streptococci by latex agglutination

Latex agglutination was compared with fluorescent-antibody staining with group A conjugate and Lancefield precipitation for grouping of beta-hemolytic streptococci. Latex agglutination correctly grouped 98.8% of 82 group A streptococci and more than 95% of 187 group B, C, or G streptococci. Occasional cross-reactions occurred between groups A and C and groups B and G.