Detection of enterotoxigenic genes in Staphylococcus aureus isolated from bulk tank cow’s milk samples in the Czech Republic

Milk and dairy products can be frequently contaminated with enterotoxigenic Staphylococcus aureus which is often involved in staphylococcal food poisoning. The aims of this study were to study the occurrence of S. aureus in bulk tank milk samples and to test their potential to produce staphylococcal enterotoxins (SEs). A total of 511 bulk tank milk samples were collected from 305 farms in 9 different regions of the Czech Republic. S. aureus was detected in 199 (38.9%) samples. The S. aureus positivity rates varied with sample origin (farm) and ranged from 0 to 67%. The potential to produce enterotoxins A-J was confirmed in 89 (44.7%) of 199 S. aureus isolates. The most commonly detected genes were seg (35.2%) and sei (31.7%). Both genes were detected in 23% of the isolates. Other genes detected were seb (in 5.0% of enterotoxin-positive isolates), seh (5.0%), sed (4.0%), sec (2.5%) and sej (0.5%). The variation in the rates of toxigenic isolates can be attributed primarily to the colonization of farms by specific clones of S. aureus