Characterisation of Staphylococcus aureus strains isolated from cows milk

The aim of the study was to characterise the Staphylococcus aureus strains isolated from unprocessed cow's milk for staphylococcal superantigenic toxin genes (sea-selu and tst), to examine the presence of mecA gene and to determine the type of staphylococcal protein A (spa) gene. The type of the gene was determined for all 68 Staphylococcus aureus strains, based on the polymorphism of a number of repeated motifs found in the region X of spa. The genes forming the egc 1 cluster, i.e. seg, sei, selm, seln, and selo were found to be the most prevalent (29.4%). Three isolates (4.41%) carried seh and one (1.47%) the seb/selk genes. No tst and mecA genes were found in the examined S. aureus. Spa types containing three and six to 14 repeats were found in the studied S. aureus population. Strains harbouring eight, ten, and twelve repeats were most frequent (33.82%, 29.41%, and 13.23%, respectively).