Streptococcal ecovars associated with different animal species: epidemiological significance of serogroups and biotypes

Traditionally the classification and identification of streptococci from clinical and veterinary sources have been based on the serogrouping of the carbohydrate antigens of the cell walls by the method of Lancefield (1933). This classification, devised for beta-haemolytic streptococci, was unable to accommodate all streptococci because many alpha and non-haemolytic strains do not possess the groupspecific antigen.