Abstract
The presence and quantity of protein A in Staphylococcus hyicus subsp. hyicus isolates from pigs, chickens and cows were examined. Cell-bound protein A was demonstrated in 42 (89.4%) of 47 isolates from diseased pigs and in 105 (79.5%) of 132 isolates from healthy pigs by a slide hemagglutination test, but not in any isolates from chickens and cows. In the immunodiffusion test with digested cell supernatants, almost all of these swine isolates formed a precipitating line against human IgG, which fused with the precipitating line formed by protein A of Staphylococcus aureus strain Cowan I. When the quantity of cell-bound protein A was determined by a microplate hemagglutination test with digested cell supernatants, most of the swine isolates showed lower titers of 32 to 256, as compared with S. aureus (5, 120). On the other hand, protein A was also demonstrated in the culture supernatants of swine isolates, but it seemed to be cell-bound protein A, which was released into the medium from the bacterial cell walls.
