Comparison and Evaluation of Diagnostic Assays for Clostridium difficile Infection

ABSTRACT

BACKGROUND: Clostridium difficile is a leading causative microorganism of pseudomembranous colitis (PMC) and antibiotic-associated diarrhea. In patients who have a history of antibiotic use and diarrhea, the presence of the C. difficile toxin should be confirmed to diagnose C. difficile infection (CDI). In this study, the results of three assays for CDI, which were performed on 1,363 clinical stool samples at a tertiary hospital, were analyzed to evaluate the performance and usefulness of these assays for diagnosis of CDI. METHODS: The results of the VIDAS C. difficile Toxin A&B Immunoassay (bioMérieux SA, France), Xpert C. difficile Real-Time PCR Assay (Cepheid, USA), and ChromID C. difficile Agar (bioMérieux SA, France) culture were analyzed retrospectively. Cases were defined as CDI according to the positive Xpert assay or the positive VIDAS assay and/or culture in the presence of PMC findings after radiological imaging or endoscopic procedures. RESULTS: A total of 1,027 samples (75.8%) tested negative in all three assays, 101 samples (7.4%) tested positive in all three assays, and overall agreement among them was 82.7%. In this study, 291 cases (21.3%) were diagnosed as CDI. Sensitivity and specificity of the VIDAS assay were 38.8% and 99.3%, and those of ChromID culture were 71.5% and 96.5%, respectively. The Xpert assay showed good sensitivity (98.6%, 287/291), whereas the VIDAS assay and ChromID culture showed low sensitivities. CONCLUSIONS: These results suggest that rapid molecular diagnostic assays, such as the Xpert assay, are promising candidates for an initial diagnostic test for CDI.