EN
The strains of Micrococcaceae family isolated from the samples of milk were assayed. One thousand five hundred and sixty four strains were classified as Staphylococcus pyogenes and 2042 as Staph, epidermidis. Out of the S. pyogenes strains 86.1 per cent caused haemolysis on agar media with blood and out of S. epidermidis — 67.5 per cent. The strains of S. pyogenes influenced much more often the increase of somatic cells in milk compared with S. epidermidis. The differences were statistically significant (p<0.001). Of 263 acute and chronic cases of mastitis the S. epidermidis strains were isolated. Fage typing 104 strains of S. pyogenes has been done.