Detection of staphylococcal enterotoxin A from ricotta cheese by cell culture

Staphylococcal food poisoning (SFP) is a very common foodborne disease. Milk and dairy products are frequently contaminated with enterotoxigenic Staphylococcus aureus, which are often involved in SFP. These foods may become contaminated owing to subclinical staphylococcal mastitis or during handling, storage and trade. For sanitary purposes, an effective approach is to detect the staphylococcal enterotoxins directly in foods, rather than detect, count and type the isolated S. aureus strains, because the toxin is the causative agent of foodborne illness. This paper illustrates a cell-based bioassay that uses the PEB (bovine embryo lung cells) cell line to detect staphylococcal enterotoxin type A (SEA) directly from artificially contaminated ricotta cheese. The test was able to detect SEA in the contaminated samples after 24 and 48 h of incubation at 37C, while results were uncertain when the samples were incubated for 72 h. The test proved to be easy to use and rapidly provided results.