Detection of Staphylococcus aureus and enterotoxin genotype diversity in Monte Veronese, a Protected Designation of Origin Italian cheese.
OBJECTIVE
To evaluate the risk associated with the load and enterotoxigenicity of Staphylococcus aureus in Monte Veronese, a PDO (Protected Designation of Origin) cheese of the Lessinia area (Verona, Italy).


RESULTS
Staphylococcus aureus was quantified by a conventional culture method and by a nucA targeted real-time PCR assay developed in this study. Staphylococcus aureus numbers in cheese were higher than the limit tolerated by the Italian food legislation in 78% instances, according to both detection methods. Multiplex PCR tests for 17 Staph. aureus enterotoxin (SE) genes were applied to nucleic acids extracted from curds, cheeses and Staph. aureus isolates. The SE gene diversity appeared reduced after ripening. The gene encoding SED was found most frequently in dairy samples and the enterotoxin genes ser, sed, seg and sem predominated in the isolates.


CONCLUSIONS
The occurrence of enterotoxigenic Staph. aureus strains with complex SE genotypes in this PDO cheese at numbers often exceeding the Italian tolerance threshold represents an important risk factor.


CONCLUSIONS
The high frequency of contamination of Monte Veronese PDO cheese and, expectedly, similar typical productions from raw milk, by enterotoxigenic Staph. aureus imposes a tighter hygienic control in the earlier manufacturing phases.
Poli
A
A
Dipartimento di Medicina e Sanità Pubblica, Università di Verona, Verona, Italy.
Guglielmini
E
E
Sembeni
S
S
Spiazzi
M
M
Dellaglio
F
F
Rossi
F
F
Torriani
S
S
D002611:Cheese / Q000382:microbiology*; D004768:Enterotoxins / Q000235:genetics*; D005516:Food Microbiology; D014644:Genetic Variation; D005838:Genotype; D016133:Polymerase Chain Reaction; D013202:Staphylococcal Food Poisoning / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification*
D004768:Enterotoxins