ABSTRACT
The group A beta-hemolytic streptococci are grampositive cocci. Within actively spreading lesions, diplococcal forms predominate, whereas in purulent exudates, chain formation tends to occur.
The organisms have a capsule containing hyaluronic acid; the cell wall has three components:
1. A protein component containing M,T, and R antigens 2. The carbohydrate moiety that contains rhamnose
N-acetylglucosamine, the group-specific carbohydrate for the group A streptococci
3. The peptidoglycan moiety
The M protein is closely associated with the virulence of group A streptococci. It interferes with the ingestion of the streptococci by phagocytic cells.
