Characterization of staphylococci isolated from mastitic cows in Spain

A total of 57 gram-positive, catalase-positive cocci, considered etiological agents of clinical and subclinical bovine mastitis, were tested for glucose and mannitol fermentation, coagulase and thermonuclease production, sensitivity to lysostaphin, gelatin hydrolysis, lysozyme, phosphatase and egg yolk factor production, hemolytic properties, antibiotic sensitivity, susceptibility to human and bovine phages, and enterotoxin production. All 57 strains were identified as staphylococci. A good correlation was found between 3+ and 4+ coagulase reactions, thermonuclease production, and high sensitivity to lysostaphin. Neither mannitol fermentation nor production of other enzymes appeared to be a specific property of bovine Staphylococcus aureus strains. beta- and delta-hemolysins were more frequently found than alpha-hemolysin. Nearly 40% of the strains were penicillin resistant. Strains were lysed by phage 42E from the human phage set more frequently than by phage 42D, whereas with the bovine set, strains were more sensitive to specific bovine phages. Three strains produced enterotoxin C, and one strain produced enterotoxin D.