OCCURRENCE OF NOCARDIA-ASTEROIDES MASTITIS IN AUSTRIAN DAIRY-COWS

In 1993 an increased number of cases of nocardia mastitis was diagnosed. From 8853 milk samples submitted from Lower Austrian herds for diagnostic reasons, 371 (4.2 %) were positive for Nocardia spp. Based on their biochemical properties the isolated microorganisms were identified as Nocardia asteroides. Sensitivity tests against neomycin and enrofloxacin showed positive results. A certain dry-off cow formulation (benzylpenicillin-procain/dihydrostreptomy-cinsulfate) was used in 90.2 % of affected cows. This suspicious antibiotic product was tested using guinea pigs and mice and bacteriological sterility tests, but no contamination with Nocardia spp. could be found. The frequency of nocardia mastitis was significantly decreasing after the product was withdrawn from the market. These examinations could not clarify in which way the use of this dry-off formulation was the predisposing factor. Outbreaks occurred 3 - 4 weeks after drying off the cows or a few days or weeks after parturition. The treatment of affected cows was in any case unsuccessful due to the severe lesions in the udder. Histologically either acute, suppurative-necrotising or chronic granulomatous mastitis was found.