Characteristics of bovine Staphylococcus aureus with special regard to clumping factor activity.

The occurrence of the following groups of bovine Staphylococcus aureus with characteristic patterns of biochemical reactions and sensitivities to phages was confirmed by the present investigation of 662 isolates from the udders of cows in 53 dairy herds: (1) host-specific variety (v) bovis, (2) not alloted strains with the basic marker, crystal violet type A (group na CV A), (3) group na CV C. The latter was split into three subgroups clearly differing in phage susceptibility patterns: I/119, I without 119 and III, respectively. Lack of clumping factor activity occurred in 323 out of 346 (93%) phage pattern I/119 strains examined while most or all isolates of the other groups of bovine strains proved to be clumping-positive.