title: Comparative performance of the GeneXpert C. difficile PCR assay and C. diff Quik Chek Complete kit assay for detection of Clostridium difficile antigen and toxins in symptomatic community-onset infections.
abstract: OBJECTIVE
  To evaluate the performance of the GeneXpert C. difficile assay and C. diff Quik Chek Complete (QCC) kit for the detection of toxins from fecal specimens and cooked meat broth (CMB) culture using toxigenic stool culture as reference method, for the diagnosis of C. difficile infection (CDI) in a community setting.
  
  
  METHODS
  Non-repeat stool samples were tested simultaneously by GeneXpert and QCC. Toxin detection was done on neat stool samples, inoculated CMB, and isolated colonies.
  
  
  RESULTS
  Nineteen (4.6%) of 409 samples were positive for glutamate dehydrogenase (GDH) in stool and CMB by the QCC assay; seven (1.7%) were positive for both GDH and toxins A/B. The sensitivities of QCC to detect C. difficile toxin directly in stool specimens and CMB were 68.4% and 100%, respectively, while specificities were 100% and 83%, respectively. C. difficile toxin was detected in 10 (2.5%) specimens and 13 (3.2%) CMB. Thirteen (68.4%) of 19 isolates were positive for C. difficile toxin by GeneXpert and QCC and were taken as the reference toxigenic culture. The disease burden was thus 3.2%. The sensitivities of GeneXpert in stool and CMB were 81.3% and 100%, respectively, while specificities were 100% and 100%, respectively.
  
  
  CONCLUSIONS
  The GeneXpert assay was more sensitive than QCC for the detection of C. difficile toxin in stool, but both assays were highly specific.
authors.affiliation: Department of Microbiology, Faculty of Medicine, Kuwait University, PO Box 24923, Safat 13110, Kuwait. Electronic address: wjamal@hsc.edu.kw.
authors.forename: Wafaa
authors.initials: W
authors.lastname: Jamal
authors.affiliation: Department of Microbiology, Faculty of Medicine, Kuwait University, PO Box 24923, Safat 13110, Kuwait.
authors.forename: Eunice M
authors.initials: EM
authors.lastname: Pauline
authors.affiliation: Department of Microbiology, Faculty of Medicine, Kuwait University, PO Box 24923, Safat 13110, Kuwait.
authors.forename: Vincent O
authors.initials: VO
authors.lastname: Rotimi
mesh_terms: D000942:Antigens, Bacterial / Q000032:analysis*; D001427:Bacterial Toxins / Q000032:analysis*; D016360:Clostridioides difficile / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D017714:Community-Acquired Infections / Q000175:diagnosis*; D004761:Enterocolitis, Pseudomembranous / Q000175:diagnosis*; D005969:Glutamate Dehydrogenase / Q000032:analysis; D016133:Polymerase Chain Reaction / Q000379:methods*; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity
chemical_list: D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D011933:Reagent Kits, Diagnostic; D005969:Glutamate Dehydrogenase
keywords: Antigen detection; Clostridium difficile; EIA; Gene Xpert; Toxin