Biovars of coagulase-positive staphylococci isolated from bovine mastitic milk.

Fifty strains of coagulase-positive staphylococci associated with bovine mastitis were biotyped. Of them, 20 were identified as biovar C (cattle & sheep), 17 as biovar B (poultry & swine), 2 as biovar D (hares) and 1 as biovar F (pigeon & fox). Of the remaining strains, 2 were closely related to human biovar A, 2 failed one property to be classified as biovar B, 3 shared properties of biovars B and D and 3 could not be identified. Bovine strains belonging to biovar C formed an heterogeneous group showing differences in crystal violet growth type and production of alpha haemolysin. Only strains associated with biovar A were Tween 80 positive. The highest incidence of lytic reactions amongst all biovars was with phages 42 E (III) and 102 (IV). Antibiotic resistance was most frequently found in biovar C (65%). The 2 strains in biovar D, one classed as biovar C and one as intermediate, were enterotoxigenic (C or D toxins).