Detection of Staphylococcal Enterotoxins in Rice Using Enzyme Immunoassay Kits

Abstract

Four commercial enzyme immunoassay kits specific for the detection of staphylococcal enterotoxins (SE) were used to examine Stayhylococcus aureus strains isolated from samples of food poisoning outbreaks. Results showed that 89.5% and 10.5% of the strains tested could produce SEA and SEC, respectively. No SEB or SED producing strains were observed. A S.aureus strain which produces SEA was inoculated into some sterilized cooked rice at a concentration of 1.7x103 CFU/g. After 6 h incubation at 37℃,cell concentration reached 2.5x105 CFU/g and SEA reached O.11 ng toxin/g. When the rice sample was kept at 4℃ for 48 h, cell growth and toxin production was not detected. Using eight strains of non-S.aureus bacteria which may be commonly found in foods, was used as control to test the detection specificity of the four commercial available enzyme immunoassay kits. Results showed that no cross-reaction had occurred indicating that the kits are highly specific for enterotoxin detection.