Bovine clinical mastitis due to coagulase-negative staphylococci and their susceptibility to antimicrobials.

A total of 168 coagulase-negative staphylococci (CNS) strains were isolated from milk samples taken from cows with clinical mastitis. The samples were collected between January 1990 and August 1992 from cows in the veterinary surveillance area of the Ambulatory Clinic, College of Veterinary Medicine, Hautjärvi, Finland. In 100 cases the effect of antibiotic treatment was evaluated 3-4 weeks after initial sampling. Clinical symptoms of the animals were recorded, and the inflammatory status of their udders was evaluated using the CMT test and assessing milk NAGase activity. CNS mastitis was most common in young cows during early lactation. Staphylococcus hyicus, S. simulans and S. epidermidis were the most frequently isolated CNS. Clinical symptoms were most severe with S. hyicus. Cure rates for CNS induced mastitis were high.