Lancefield’s classification [Rebecca C. Lancefield, American bacteriologist, 1895–1981] , a serological classification of streptococci based on their antigenic characteristics. The bacteria are divided into 13 groups by the identification of their pathological action. Group A contains most of the streptococci that cause infection in humans. Groups B to O are less pathogenic and are often present without causing disease. Most are hemolytic; of those, the beta subgroup is the most likely to be the cause of infection.
