Features of streptococcal disease and cellulitis

Streptococci were first identified by Billroth in 1874 in infected wounds and to this day remain one of the most important human pathogens. Traditional classification of streptococci is by Lancefield groups and haemolytic activity on blood agar, but recent genetic analysis has allowed more accurate subdivision into six groups. Of these groups, the pyogenic streptococci (groups A, B, C and G) are the most important skin pathogens.