Enterotoxins production and coagulase gene polymorphism of Staphylococcus aureus isolated from dairy products. Relation between genetic types and enterotoxins.

摘要

Staphylococcus aureus is a known major cause of foodborne illnesses, and milk and dairy products are often contaminated by enterotoxigenic strains of this bacterium. We tested 130 S. aureus strains, 122 isolated from dairy products (milk, curd, cheeses, butter and whey) and 8 from human samples in Italy, for SE production, using the Reverse Passive Latex Agglutination method. Most of the enterotoxigenic strains produced SEA (44%), but SED (33%), SEC (21%) and SEB (2%) were also detected. To explore the genetic relationship between enterotoxin producing isolates and non-enterotoxigenic strains, we carried out coagulase (coa) gene restriction fragments length polymorphism analysis (RFLP). We distinguished 6 different coa types. On the basis of the RFLP polymerase chain reaction, 31 different coa subtypes were identified, and 17 of the RFLP profiles revealed enterotoxigenic S. aureus strains. On comparing the results, no link was found between the different coa RFLP subtypes and staphylococcal enterotoxin production.