Detection of Clostridium difficile Toxin A by immunoblotting.

A clinical isolate of Clostridium difficile has been tested for its toxin production. Both toxins, toxin A and toxin B, could be detected by tissue culture and in animal models as well. Antibodies against a crude toxin A preparation have been prepared. These antibodies are able to neutralize the toxin both in the mouse lethality test and tissue culture test systems. The specificity of this antiserum has been analysed by electroimmunoprecipitation methods. Using immunoblotting, it could be demonstrated that the antigenicity of toxin A after SDS polyacrylamide gel electrophoresis under denaturing and reducing conditions was still preserved. The molecular weight of toxin A has been estimated to be 250000. Immunoblotting offers a simple and reliable procedure for toxin A detection from culture supernatants of C. difficile.