Characteristics of Staphylococcus Xylosus Isolated from Subclinical Mastitis in Cows

The aim of the present study was to determine virulence factors and antibiotic susceptibility of Staphylococcus xylosus isolated from subclinical mastitis in cows. The material consisted of 42 isolates of S. xylosus obtained from 276 samples of milk collected from cows with subclinical mastitis. The isolates were obtained from the udder secretions of 33 cows from farms in the Lublin region (Poland). S. xylosus was found in 15.2% of tested milk samples. The study did not reveal any macroscopic changes in the milk or symptoms in the cow’s body. The number of somatic cells in milk samples ranged from 245,000 to 416,000/ml of milk (on average 268,000/ml of milk). The ability to produce slime was observed in 42.9% of S. xylosus isolates. None of the tested isolates demonstrated the ability to produce protease or cause haemolysis. Five isolates of S. xylosus (11.9%) were classified to the methicillin-resistant group. The mecA gene was not found in any of these isolates. The enzyme β-lactamase was detected in 28.6% of S. xylosus isolates. The highest efficacy against S. xylosus was demonstrated for cephalosporin antibiotics: cefacetrile and cefoperazone (80.1% and 76.2% of susceptible isolates of S. xylosus, respectively). A significant quantity of isolates was resistant to streptomycin, linkomycin, penicillin and neomycin (approximately 10% of susceptible isolates of S. xylosus).