Objective: The aim of the present study was to assess the correlation of Triage Micro Clostridium difficile Panel and toxin B cytotoxicity assay with the clinical diagnosis of C. difficile diarrhea.
Methods: The subjects evaluated were 98 patients with diarrhea for whom stool was submitted for testing for C. difficile. Clinical symptoms prompting evaluation, laboratory values, comorbid illness, and treatment outcomes that provided clinical insight into the etiology of the diarrhea were recorded. These data were then reviewed by two experienced clinical gastroenterologists who were blinded to the results of the Triage enzyme immunoassay and cytotoxin B assay. The final diagnosis of C. difficile diarrhea was based on the patient's clinical evaluation and symptoms, treatment, and subsequent outcome.
Results: Of 98 patients evaluated, 33 were diagnosed with C. difficile diarrhea by clinical criteria. The toxin B assay displayed 88% sensitivity and 100% specificity and positive predictive value. The toxin A component of the Triage Panel displayed 45% sensitivity but 98% specificity and 94% positive predictive value. The common antigen had 97% sensitivity and 95% negative predictive value. Among the 45 patients with only a common antigen detected, the most common diagnoses for diarrhea were chemotherapy-related, antibiotic-related diarrhea, and graft versus host disease.
Conclusions: Our data show that both the Triage Micro C. difficile Panel and cytotoxin B for C. difficile have a high positive predictive value and negative predictive value for C. difficile diarrhea. The Triage Micro C. difficile Panel provides a reasonable alternative to the cytotoxin B assay in the assessment of clinically relevant C. difficile. The Triage Micro C. difficile Panel is less labor intensive and less expensive than cytotoxin B assay. The panel approach improves on the individual assay performances by increasing sensitivity and negative predictive value. When both common antigen and toxin A are positive, the likelihood of C. difficile diarrhea is high; conversely, when both results are negative, the likelihood of C. difficile diarrhea is low.