Virulence factors in streptococci.

In man streptococcal septicaemia is most often associated with the streptococci of Lancefield's groups, A, B and D, with pneumococci, with Streptococcus milleri and with viridans streptococci. The specific determinants of the ability of streptococci to establish infection and to invade the blood stream are only partially understood. Even if fully comprehended, they would provide an incomplete picture of the factors responsible for the capacity of streptococci to produce a myriad of disease states the clinical expression of which include such diverse manifestations as acute sore throat, impetigo contagiosa, scarlet fever, erythema marginatum, St. Vitus dance, mitral stenosis, bloody urine and dental caries, to name only a few.