Detection of classical genes and enterotoxins of Staphylococcus aureus isolated from raw milk in the south-east region of Poland

The aim of the study was to investigate if the enterotoxigenic strains of S. aureus isolated from raw milk are able to produce staphylococcal enterotoxins (SEs) A - E. A total of 168 of S. aureus isolates from raw milk collected in the south - east region of Poland (Lubelskie Province) were tested for SE production by the ELFA, while multiplex PCR was applied for detection of enterotoxin genes (sea, seb, sec, sed, see). It was found that 20 (11.9%) out of 168 strains were positive for one or more classical SE markers and 19 of them produced a detectable level of enterotoxins. The results obtained by mPCR and ELFA were in agreement, when the presence of A, B, and D toxin types was tested; whereas SEC was not found by the ELFA although the S. aureus was positive for the respective gene. The results of the two methods showed that mPCR identified one more strain potentially producing enterotoxin than the ELFA, which may suggest that the enterotoxigenic S. aureus are not always able to express the toxin protein.