Comparison of four methods for the detection of staphylococcal enterotoxin in foods from outbreaks of food poisoning

Abstract

Two commercial kits, a sandwich-ELISA and a reversed passive latex agglutination (RPLA) kit, were used together with a gel-diffusion and a microtitre plate ELISA method for the detection of staphylococcal enterotoxins in foods from outbreaks of food poisoning. With the ELISA kit enterotoxin was detected in foods from 15 outbreaks. In 13 of these foods the number of Staphylococcus aureus present was >1×10 6/g and in two samples of cheese enterotoxin A was found in the absence of detectable S. aureus. These results were similar to those obtained with the plate ELISA. With the RPLA kit, food extracts were used 5 times more concentrated than recommended by the manufacturer and enterotoxin was detected in 12 of the 15 foods positive by ELISA. With the gel-diffusion method enterotoxin was found in 6 of 9 ELISA positive foods. Using both ELISA methods and the RPLA kit enterotoxin was not detected in foods from 8 outbreaks with counts of ⩽700 to 1×10 6 S. aureus/g. The RPLA test was easy to perform, but the sensitivity of the ELISA methods was needed to detect enterotoxins in some of the foods from outbreaks.