Serogroups and biotypes among beta-hemolytic streptococci of canine origin.

A study of hemolytic streptococci from clinical infections in dogs revealed the presence of four serogroups, with one to four biotypes in each, based on carbohydrate fermentation patterns. Of 254 isolates tested, 206 belonged to Lancefield group G, 30 to group C, 7 to group E, and 1 to group A. Ten isolates could not be grouped. Reactions on the three key carbohydrates, lactose, trehalose, and sorbitol, revealed four biotypes each in groups G and C, and two in group E and among the ungroupable cultures. The most common pattern, seen in 154 cultures, was lactose fermentation with no action on trehalose and sorbitol, and corresponded to that described for Streptococcus canis (Stafseth et al., J. Am. Vet. Med. Assoc. 90:769-781, 1937). Most of the strains originated from skin, subcutaneous and wound infections, genitourinary lesions, otitis externa, and respiratory disease. Data suggest that group G streptococci may be preferentially parasites of the urogenital tract.