ABSTRACT
In 1933, Rebecca Lancefield, by means of a precipitin reaction, serologically identified and grouped the streptococci according to their cellular carbohydrates. Initially, she identified five antigenically distinct streptococcal groups and designated them A, B, C, D, and E. Since these earlier observations, 18 groups, A through H and K through T, have been identified. The groups A, B, C, D, and G are the principal groups associated with human disease.
