Development and Evaluation of Simple Dot-Blot Assays for Rapid Detection of Staphylococcal Enterotoxin-A in Food.

The present study was aimed to develop and evaluate dot-blot assays for rapid detection of staphylococcal enterotoxin-A (SEA) in food. Dot blots were developed in two formats, indirect and sandwich utilizing mouse monoclonal anti-SEA and rabbit polyclonal anti-SEA antibodies. In indirect dot-blot format, recombinant SEA was directly coated on NCM dot-blot strip and detection was carried out by anti-SEA antibodies. In sandwich dot-blot format, SEA was trapped between anti-SEA capture and detection antibodies. Both the dot-blot assays exhibited a sensitivity of ~48 ng ml-1 when tested in different food matrices. The developed assays were highly specific as no cross-reactivity was detected with other classical staphylococcal enterotoxins, toxigenic bacteria and foodborne pathogens. Sensitivity and specificity of developed indirect and sandwich dot-blot assays with respect to PCR was found to be 100 and 99%, respectively. The results shows that the developed dot-blot assays can be used as rapid preliminary screening tests for detection of SEA in food or determining the toxigenic potential of staphylococci, especially in resource-limited settings.