EN
The observations performed in 1989—1990 showed that accidents of clinical mastitis ranged from 7.6 to 17.2%. The disease was noted more often in primiparous (up to 28%) than in multiparous cos (15%). The main cause was Streptococcus agalactiae — mean 31.5%, then mixed microflora — 18.4%, beta haemolytic Escherichia coli — 17%, Gram negative bacteria — 12%, Staphylococcus aureus — 10.5%, Streptococcus uberis — 8%, yeast-like fungi 2%. Abacterial mastitis was diagnosed in 6% of cases. The isolated strains of streptococci causing agalactia were sensitive to penicillin (91.7%), neomycin and erythromycin, mixed flora on neomycin (85.7%), erythromycin and oxyterracin, beta haemolytic E. coli on neomycin (88.8%), streptomycin and oxyterracin, Gram negative bacteria on neomycin (100%) and oxyterracin, S. aureus on streptomycin (75%), oxyterracin (75%) and erythromycin (75%), S. uberis on oxyterracin (83.3%), penicillin and streptomycin, yeast-like fungi were resistant to all examined antibiotics.