Comparison of the mouse bioassay and enzyme-linked immunosorbent assay procedures for the detection of type A botulinal toxin in food.

Samples of chili linked to a foodborne illness outbreak of type A botulism were examined for preformed type A botulinal toxin using two enzyme-linked immunosorbent assay (ELISA) procedures and the mouse bioassay. One of the samples was positive for type A botulinal toxin and three of the samples were negative for type A, B, E, and F botulinal toxins using the three methods. The mouse bioassay indicated that type A toxin was present at the 10,000 minimal lethal dose per gram (MLD per g) of product. The ELISA tests indicated a toxicity of 7,650 MLD per g with one method and 8,350 MLD per g with the other method. The sample toxicity determined by the ELISA was estimated by comparing samples to a standard curve generated with standard type A neurotoxin in casein buffer. The ELISA methods are more rapid than the mouse bioassay, since the toxin type can be determined in 1 day. The mouse bioassay is more sensitive than the ELISA but usually requires multiple assays to obtain the toxin type and toxicity. Type A culture isolates from the sample were also verified using one ELISA method.