Enterotoxin D producing strains of Staphylococcus aureus are typeable by pulsed-field gel electrophoresis (PFGE)

Certain strains of Staphylococcus aureus (S. aureus) are capable of producing enterotoxins. In dairy products, these enterotoxins are the second major cause of foodborne disease in France. The main objective of this study was to type a selection of enterotoxigenic and non-enterotoxigenic strains of S. aureus using a reliable method, pulsed-field gel electrophoresis (PFGE), to explore the genetic relationships between enterotoxin producing strains in vitro and non-enterotoxigenic strains. Ninety-one enterotoxigenic strains of S. aureus, and 20 non-enterotoxigenic strains, were typed by pulsed-field gel electrophoresis after digestion using SmaI endonuclease. This study revealed a specific profile for the enterotoxin D producing S. aureus strains. Enterotoxin D is one of the enterotoxins most frequently isolated in food-poisoning outbreaks, after enterotoxin A, implicating dairy products. Of the 29 PFGE profiles observed, the enterotoxin producing strains of S. aureus were represented by 24 of these profiles. However, no link was found between the different biotypes and the PFGE profiles. Interestingly, all the in vitro enterotoxin D producing strains were clustered in one pulsotype.