title: Comparison of culture, cytotoxin assay and two EIA tests with clinical diagnosis of Clostridium difficile-associated diarrhea.
abstract: OBJECTIVE
  The most common etiology of infectious diarrhea in hospitalized patients is Clostridium difficile. No single laboratory test yields a definitive diagnosis. Four methods were evaluated for their sensitivity and specificity in patients who had clinically defined C difficile-associated diarrhea.
  
  
  METHODS
  Clinical criteria for C difficile-associated diarrhea were defined. All adult in-hospital patients whose stools were tested for C difficile were prospectively followed. Stools were examined with culture on a selective medium, a commercial cytotoxicity assay (cta), and two commercially available enzyme immunoassays (eias) for toxin A (Meridian) and toxin AB (cbc).
  
  
  RESULTS
  During the study period 235 stool specimens from 185 patients were tested. Fifty-one patients were positive for C difficile or its markers, cta was most sensitive (80%), whereas cbc-eia was most specific (98%). Differences in the sensitivities of cta and Meridian-eia were minor (80% versus 73.3%) and they were equally specific (95.5%).
  
  
  CONCLUSIONS
  The sensitivity and specificity of eia for toxin A is similar to other tests. However, due to rapidity and ease of performance, it may be a more practical test for the diagnosis of C difficile-associated diarrhea, especially if the cytotoxin assay is not available.
authors.affiliation: Department of Microbiology and Infection Control, Victoria Hospital; and Division of Infectious Disease, and Department of Microbiology and Immunology, The University of Western Ontario, London Ontario.
authors.forename: M
authors.initials: M
authors.lastname: Binning
authors.forename: M A
authors.initials: MA
authors.lastname: John
authors.forename: B C
authors.initials: BC
authors.lastname: Schieven
authors.forename: T W
authors.initials: TW
authors.lastname: Austin
authors.forename: R
authors.initials: R
authors.lastname: Lannigan
authors.forename: Z
authors.initials: Z
authors.lastname: Hussain