Antimicrobial susceptibility of ruminal coagulase-negative staphylococci.

The species Staphylococcus sciuri subsp. sciuri, Staphylococcus sciuri subsp. lentus, Staphylococcus saprophyticus and Staphylococcus xylosus of novobiocin resistant coagulase-negative staphylococci (CNS) isolated from rumen content or wall of lambs and calves were determined. All bacteria were tested for lactic acid production, urease, adherence activities and antimicrobial susceptibility or resistance. The majority of strains presented belonged to bacteria with low affinity for epithelial cells. Only Staphylococcus xylosus SX63 was detected as a strain with high adherence activity. Urease activity in isolates reached the average value of 12.72 nkat.mL-1. The strain SS1 showed high urease activity and SI97 strain was without urease activity. Most strains showed resistance to ionophores. All bacteria were found as sensitive to nonionophores without Staphylococcus xylosus SX63 (tylosin) and Staphylococcus sciuri subsp. lentus SL139 (nitrovin). Each of the strains tested inhibited the growth of at least one of the indicators reaching clear inhibition zones (2-5 mm in diameter). Of 12 strains tested, in 6 bacteria production of bacteriocin-like substances was affected using additional nutrient media. Generally, novobiocin resistant CNS are among the most frequent representatives of the staphylococcal group colonizing the rumen of young ruminants.