Changes in prevalences of pathogens and antibiotic resistance patterns in connection with catarrhalic mastitis in sairy cattle

Evaluation of about 20.000 quarter milk samples per year from dairy cows wi th mastitis showed an average participation of Streptococci and Staphylococ ci of 35 per cent each in the years 1990 to 1997. Differentiation of the St reptococci showed an increased involvement of S. uberis from 34 per cent to 56 per cent and a decrease of S. agalactiae eases. The laboratory results implicate a change of the causative agents and therefore a change of the wa ys of infection. Despite of herd health programs aimed at reducing staphylo coccal mastitis, there was no overall decrease in staphylococci isolates. T here was no increase of antimicrobial resistance in streptococcal and staph ylococcal species isolated from bovine mammary glands throughout the last 8 years.