title: Detection of enterotoxigenic Staphylococcus aureus isolates in raw milk cheese.
abstract: OBJECTIVE
  To develop an easy, rapid and efficient DNA extraction procedure for Staphylococcus aureus detection with a low number of steps and removing completely the PCR inhibitors, applicable to raw milk cheese samples, and to compare phenotypical and genotypical method to detect Staph. aureus isolates and staphylococcal enterotoxins (SEs) production.
  
  
  RESULTS
  A total of 33 bovine and caprine raw milk cheese samples were analysed by means of both classic microbiological and molecular techniques. All samples were positive for Staph. aureus contamination. The DNA extraction protocol optimized was found to achieve a detection limit of 100 CFU g(-1) for Staph. aureus. None of the samples tested with immunological assays contained SEs but in 14 of 33 samples a mixture of se positive (sea, sec, sed, seg, sel, sej) isolates were identified.
  
  
  CONCLUSIONS
  Staphylococcus aureus is a food-borne pathogen mainly detected in finished dairy products. The rapid and efficient detection of Staph. aureus isolates from dairy products is essential for consumer safety. The direct detection of pathogens from food is possible with careful attention to sample preparation and nucleic acid amplification optimization.
  
  
  CONCLUSIONS
  This study shows that raw milk cheese samples can be tested for Staph. aureus contamination with a rapid, simple and reproducible procedure.
authors.affiliation: Department of Biomedical Sciences and Technologies, University of Milan, Segrate, Milan, Italy. paola.cremonesi@unimi.it
authors.forename: P
authors.initials: P
authors.lastname: Cremonesi
authors.forename: G
authors.initials: G
authors.lastname: Perez
authors.forename: G
authors.initials: G
authors.lastname: Pisoni
authors.forename: P
authors.initials: P
authors.lastname: Moroni
authors.forename: S
authors.initials: S
authors.lastname: Morandi
authors.forename: M
authors.initials: M
authors.lastname: Luzzana
authors.forename: M
authors.initials: M
authors.lastname: Brasca
authors.forename: B
authors.initials: B
authors.lastname: Castiglioni
mesh_terms: D000818:Animals; D001431:Bacteriological Techniques; D002417:Cattle; D002611:Cheese / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D004768:Enterotoxins / Q000096:biosynthesis* / Q000235:genetics; D006041:Goats; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D013211:Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D004768:Enterotoxins