Udder health from the laboratory point of view

A reliable micro biological analysis of milk samples incl. antibiogram remains fundamental when combating mastitis on herd level. The present paper summarizes the results of mastitis pathogen isolation performed at the "milk laboratory" of the institute between 2004 and 2010. For that, quarter or half foremilk and animal composite milk samples (n = 61.357) were analysed according to NMC recommendations. In case of bacteriologically positive results, antibiograms were made for selected strains (n = 22.859; MIC performed according to CLSI [M31-A3]). Approx. 1/3 of samples originated from the university's clinics, the rest from local veterinarians and dairy farmers (predominantly Northern Germany). Cows amounted for 96.5 % of samples, sheep and goats for 3.4 %, and equines and zoo animals (Patagonian mara Dolichotis patagonum, night monkeys Aotus spp.) for 0.1 %. More than half of samples (52-57 %) resulted bacteriologically positive. Those samples from cows contained coagulase-negative staphylococci (CNS; 24 %), Streptoccoccus uberis (13 %), Corynebacterium spp. (12 %), Escherichia coli (12 %), Staphylococcus aureus 19 %), Enterococcus spp. and yeasts (7 % each) as well as other pathogens (17 %). In goats and sheep, CNS 166 %) and S. aureus 119 %) predominated. The amount of cow-associated pathogens decreased in favour of environmental and opportunistic pathogens. The evaluation of antibiograms showed that many of the most frequently isolated pathogens of bovine mastites (except for E. col!) displayed high and stable sensitivity rates (> 95 %) towards several antibiotics (e. g. oxacillin, ampicillin). Resistance towards some other products (e. g. erythromycin, tetracyclines) increased markedly.