EN
The purpose of the review is to describe the role of coagulase-negative staphylococci (CNS) as etiological agents of mastitis in cows. Apart from streptococci and coliforms Staphylococci are currently the main etiological agents of udder inflammations. A typical feature that distinguishes more pathogenic from less pathogenic Staphylococcus species is the ability to produce of free coagulase and bound coagulase (clumping factor) through isolates. Strains that produce coagulase (coagulase-positive staphylococci; CPS) are simply called Staphylococcus aureus that belong to the major mastitis pathogens. As they are less pathogenic coagulase-negative staphylococci (CNS) have been regarded as minor mastitis pathogens. The prevalence of mastitis caused by CNS definitely increased during last decade and presently these bacteria have became the most common etiological agents of mastitis in many countries. Among CNS, Staph. chromogenes, Staph. hyicus, Staph. epidermidis, Staph. simulans, Staph. warneri, Staph. xylosus and Staph. sciuri are most frequently isolated from mastitis. Changes in milk connected with CNS are less intensive if compare to those caused by CPS even in cases of subclinical forms of mastitis. Some CNS species as Staph. chromogenes and Staph. simulans seem to be more pathogenic because they were more frequently isolated from clinical mastitis. It seems the introduction of the contagious mastitis control program directed to Staph. aureus can decrease the intramammary infections by coagulase-negative staphylococci.