The aim of the study was the identification and molecular analysis of 35 Staphylococcus spp. strains, isolated from milk of cows with clinical form of mastitis, regarding to its potential ability to produce enterotoxins (SEA-SEE). All examined strains were first characterized on the basis of the image analysis of the bacterial colony growth on chromogenic medium CHROMagar Staph. aureus. In the next step all strains were analyzed using the species-specific PCR, based on detection of two molecular markers: nuc – specific for S. aureus and gehM – specific for S. xylosus. Additionally, enterotoxigenicity of identified strains (presence of sea-see genes, including secv), in the multiplex-PCR was performed. A total of 35 isolates from milk samples of bovine clinical mastitis cases were analyzed and 18 strains (51.4%) classified as S. xylosus (CNS), where only two strains (5.7%) were coagulase-positive S. aureus. Seven isolates of S. xylosus (20%) were positive for enterotoxin genes (se), as detected by multiplex-polymerase chain reaction, with sea (71.4%), secv (14.3%) and sed (14.3%). In addition, in the case of five strains (71.4%), amplicons specific for others, indefinable se genes or their variants were detected, which on the basis of in silico analysis were identified as: seg, seh, sei or selu. The data showed that the toxigenic properties of CNS should not be ignored and further investigation of this group of microorganisms in food could be very important. Moreover the research contributed to emphasize the meaning of enterotoxigenic S. xylosus strains in the etiology of cows’ mastitis. The study also confirmed the usefulness of molecular methods in detection of potentially enterotoxic Staphylococcus spp. strains, isolated from animals.

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