28 Jan

Streptococci Classification

In 1933 Rebecca Lancefield classified the streptococci on the basis of immunological groups related to carbohydrate antigens associated with the cells.  Her original groups expanded to groups A through V.  Lancefield groups are still used as an important characteristic in differentiating the streptococci, but the system is not inclusive because some streptococci, like S. pneumoniae, do not process the carbohydrate antigens.  In 1978 it was proposed that streptococci be divided into seven groups, designated pyogenic, pneumococci, oral, fecal, lactic, anaerobic, and other streptococci.  A similar grouping was adopted in the first edition of Bergey’s Manual but with pneumococci grouped with the pyogenic streptococci.  The streptococci associated with human diseases are S. pyogenes, S. agalactiae, S. pneumoniae, E. faecalis, E. faecium, and S. bovis.