title: Evaluation of the diagnostic performance of the xpert Clostridium difficile assay and its comparison with the toxin A/B enzyme-linked fluorescent assay and in-house real-time PCR assay used for the detection of toxigenic C. difficile.
abstract: BACKGROUND
  Clostridium difficile genes or toxin can be detected using several laboratory techniques. In this study, we compared the performance of the Xpert C. difficile assay with that of a toxin A/B enzyme-linked fluorescent immunoassay (ELFA) and an in-house real-time PCR assay for the tcdB gene.
  
  
  METHODS
  From April 2011 through January 2012, 138 soft or liquid stool samples from 138 adult patients at Paik Hospital were tested using the toxin A/B ELFA, in-house real-time PCR assay, and Xpert C. difficile assay to detect toxigenic C. difficile. Specimens were considered true positives if results were positive in both the in-house real-time PCR for tcdB gene and Xpert C. difficile assays.
  
  
  RESULTS
  Sensitivity of the toxin A/B ELFA, in-house tcdB gene real-time PCR, and Xpert C. difficile assay were 67.6%, 97.3%, and 100.0%, respectively. The specificity of the in-house tcdB gene real-time PCR assay was 100%, while the specificity was 98.0% for the other two methods. The turnaround time (TAT) was 50 min for the Xpert C. difficile assay, 75 min for the toxin A/B ELFA, and 160 min for the in-house real-time PCR assay.
  
  
  CONCLUSIONS
  The Xpert C. difficile assay and the in-house real-time PCR assay had higher sensitivity than the toxin A/B ELFA; however, the specificities of the three assays were similar. Considering its rapid TAT and high sensitivity, use of the Xpert C. difficile assay is highly recommended for rapid and accurate diagnosis of C. difficile infection.
authors.affiliation: Department of Laboratory Medicine, Seoul Paik Hospital, Inje University College of Medicine, Seoul, South Korea.
authors.forename: Dong Hee
authors.initials: DH
authors.lastname: Whang
authors.forename: Shin Young
authors.initials: SY
authors.lastname: Joo
mesh_terms: D000328:Adult; D001427:Bacterial Toxins / Q000378:metabolism*; D016360:Clostridioides difficile / Q000302:isolation & purification*; D004761:Enterocolitis, Pseudomembranous / Q000175:diagnosis* / Q000191:economics; D004768:Enterotoxins / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay / Q000191:economics / Q000379:methods*; D006801:Humans; D011237:Predictive Value of Tests; D011933:Reagent Kits, Diagnostic / Q000191:economics; D060888:Real-Time Polymerase Chain Reaction / Q000191:economics / Q000379:methods*; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D001427:Bacterial Toxins; C488583:Clostridium difficile lethal toxin B; D004768:Enterotoxins; D011933:Reagent Kits, Diagnostic; C041348:tcdA protein, Clostridium difficile
keywords: Clostridium difficile; VIDAS; Xpert; toxin