Development and evaluation of sandwich ELISA for detection and quantification of staphylococcal enterotoxin-A in food

Staphylococcus aureus is an opportunistic zoonotic pathogen which secretes 24 different types of enterotoxins (SEs) and enterotoxin-like (SEls) proteins. Classical enterotoxins (SEA-SEE) are responsible for >95% of food poisoning outbreaks, of which SEA alone is responsible for >75% of them. This study was undertaken to develop a sandwich enzyme-linked immunosorbent assay (ELISA) for sensitive, specific, and quantitative detection of staphylococcal enterotoxins-A in food. Optimization of sandwich ELISA was attempted in two ways: rabbit polyclonal anti-SEA as a capture antibody and mouse monoclonal anti-SEA as a detector antibody, and vice versa. In the optimization of sandwich ELISA, mouse monoclonal anti-SEA as a capture antibody and rabbit polyclonal anti-SEA as a detector antibody yielded the highest sensitivity of 0.5-0.75 ng mL(-1). The developed assay was found to be highly specific and exhibited equivalent sensitivity to a commercial kit. The developed sandwich ELISA may be utilized for the detection of staphylococcal enterotoxin-A in food as a cheap alternative to available commercial kits. The developed sandwich ELISA may be useful for microbiological quality assurance of foods, especially in resource-limited developing countries.