The use of CIE for the detection of Clostridium difficile toxin in stool filtrates: laboratory and clinical correlation.

Two CIE procedures (CIE-1, CIE-2) for the detection of Clostridium difficile in diarrheal stools were evaluated by comparison to cytotoxin assay and culture results and by comparison to a clinical likelihood of C. difficile-induced diarrhea. Using a combination of toxin assay and culture results for reference, the CIE-1 and CIE-2 procedures had sensitivities of 33% and 47%, specificities of 89% and 91%, and positive predictive values of 42% and 54%, respectively. Using clinical likelihood for reference, the best results were obtained by the CIE-2 method, which yielded a positive predictive value of 77%. Neither CIE procedure provided an acceptable sensitivity for the detection of C. difficile in stools.