Haemolytic and proteolytic activity of coagulase-negative staphylococci isolated from mastitis cows.

The aim of the present study was to assess the haemolytic and proteolytic activity of coagulase-negative staphylococci (CNS) isolated from cows with mastitis. The study was conducted on 100 CNS strains: S. xylosus (n=28), S. chromogenes (n=26), S. haemolyticus (n=25), S. sciuri (n=14), S. warneri (n=4), S. hominis (n=2), S. saprophyticus (n=1); 22 CNS were isolated from cows with clinical mastitis and 78 from those with subclinical mastitis. The CNS studied showed the ability to produce only alpha-haemolysin and belonged to one strain - S. haemolyticus (21.0% of isolated CNS strains). Haemolysin-positive CNS were responsible for both clinical and subclinical mastitis (22.7% and 20.5%, respectively). The ability to produce protease was found in 31.0% of CNS belonging to two strains: S. chromogenes and S. sciuri. Protease-positive CNS were the etiological factor of both clinical and subclinical mastitis (31.8% and 30.8%, respectively). All S. xylosus, S. warneri, S. hominis, and S. saprophyticus strains were found protease-negative and haemolysin-negative, irrespective of whether they caused clinical or subclinical mastitis in cows.