Improved immunologic detection of Clostridium difficile antigen by counterimmunoelectrophoresis

An improved counterimmunoelectrophoresis (CIE) procedure for detection of Clostridium difficile antigen is described. Commercially available antiserum to C. difficile toxin was absorbed with whole cells of C. difficile. CIE (absorbed) was 100% sensitive and 77.5% specific when compared to the tissue culture toxin assay. Instances are noted in which the CIE (absorbed) and/or bacterial culture was positive and the tissue culture assay was negative.