title: Six rapid tests for direct detection of Clostridium difficile and its toxins in fecal samples compared with the fibroblast cytotoxicity assay.
abstract: Clostridium difficile is one of the most frequent causes of nosocomial gastrointestinal disease. Risk factors include prior antibiotic therapy, bowel surgery, and the immunocompromised state. Direct fecal analysis for C. difficile toxin B by tissue culture cytotoxin B assay (CBA), while only 60 to 85% sensitive overall, is a common laboratory method. We have used 1,003 consecutive, nonduplicate fecal samples to compare six commercially available immunoassays (IA) for C. difficile detection with CBA: Prima System Clostridium difficile Tox A and VIDAS Clostridium difficile Tox A II, which detect C. difficile toxin A; Premier Cytoclone A/B and Techlab Clostridium difficile Tox A/B, which detect toxins A and B; and ImmunoCard Clostridium difficile and Triage Micro C. difficile panels, which detect toxin A and a species-specific antigen. For all tests, Triage antigen was most sensitive (89.1%; negative predictive value [NPV] = 98.7%) while ImmunoCard was most specific (99.7%; positive predictive value [PPV] = 95.0%). For toxin tests only, Prima System had the highest sensitivity (82.2%; NPV = 98.0%) while ImmunoCard had the highest specificity (99.7%; PPV = 95.0%). Hematopoietic stem cell transplant (HSCT) patients contributed 44.7% of all samples tested, and no significant differences in sensitivity or specificity were noted between HSCT and non-HSCT patients. IAs, while not as sensitive as direct fecal CBA, produce reasonable predictive values, especially when both antigen and toxin are detected. They also offer significant advantages over CBA in terms of turnaround time and ease of use.
authors.affiliation: Department of Laboratory Medicine, School of Medicine, University of Washington, Seattle, Washington 98195-7110, USA.
authors.forename: David K
authors.initials: DK
authors.lastname: Turgeon
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Novicki
authors.forename: John
authors.initials: J
authors.lastname: Quick
authors.forename: LaDonna
authors.initials: L
authors.lastname: Carlson
authors.forename: Pat
authors.initials: P
authors.lastname: Miller
authors.forename: Bruce
authors.initials: B
authors.lastname: Ulness
authors.forename: Anne
authors.initials: A
authors.lastname: Cent
authors.forename: Rhoda
authors.initials: R
authors.lastname: Ashley
authors.forename: Ann
authors.initials: A
authors.lastname: Larson
authors.forename: Marie
authors.initials: M
authors.lastname: Coyle
authors.forename: Ajit P
authors.initials: AP
authors.lastname: Limaye
authors.forename: Brad T
authors.initials: BT
authors.lastname: Cookson
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Fritsche
mesh_terms: D001427:Bacterial Toxins / Q000032:analysis*; D016360:Clostridioides difficile / Q000235:genetics / Q000302:isolation & purification*; D005243:Feces / Q000737:chemistry / Q000382:microbiology*; D005347:Fibroblasts / Q000187:drug effects*; D006801:Humans; D007118:Immunoassay
chemical_list: D001427:Bacterial Toxins