Evaluation of two rapid assays for detection of Clostridium difficile Toxin A in stool specimens

Rapid laboratory diagnosis of Clostridium difficile-associated diarrhea (CDAD) is highly desirable in the setting of hospital cost containment. We tested 654 stool specimens to compare the performance of two assays for rapid detection of toxin A, the Immunocard Toxin A test (Meridian Diagnostics, In...

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Bibliographic Details
Published in:Journal of clinical microbiology 1999-09, Vol.37 (9), p.3044-3047
Main Authors: FEDORKO, D. P, ENGLER, H. D, O'SHAUGHNESSY, E. M, WILLIAMS, E. C, REICHELDERFER, C. J, SMITH, W. I
Format: Article
Language:English
Subjects:
Bacterial diseases
Bacterial diseases of the digestive system and abdomen
Bacterial Toxins
Bacteriology
Biological and medical sciences
Clostridium difficile
Clostridium difficile - pathogenicity
Diarrhea - diagnosis
Enterotoxins - analysis
Feces - microbiology
Human bacterial diseases
Humans
Immunoenzyme Techniques
Infectious diseases
Medical sciences
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Summary:Rapid laboratory diagnosis of Clostridium difficile-associated diarrhea (CDAD) is highly desirable in the setting of hospital cost containment. We tested 654 stool specimens to compare the performance of two assays for rapid detection of toxin A, the Immunocard Toxin A test (Meridian Diagnostics, Inc.) and the Culturette Brand Toxin CD enzyme immunoassay (EIA) (Becton Dickinson Microbiology Systems), with a cytotoxin assay (Cytotoxi Test; Advanced Clinical Diagnostics) and culture on cycloserine-cefoxitin-fructose agar followed by determination of the production of toxins A and B. A chart review was performed for patients whose stool specimens provided positive results on one to three of the assays. With the "gold standard" of all four assays positive or chart review evidence of CDAD, 97 (14.8%) stool specimens were positive by one or more assays and 557 (85.2%) were negative by all methods. Total agreement for all assays was 90.5% (592 of 654). The sensitivity, specificity, positive predictive value, and negative predictive value for toxigenic culture were 94.7, 98.6, 87.1, and 99.5%, respectively, for toxigenic culture; 87.7, 98.6, 86.2, and 98.8%, respectively, for the cytotoxin assay; 71.9, 99.3, 91.1, and 97.3%, respectively, for the Immunocard; and 68.4, 99.1, 88.6, and 96.9%, respectively, for the Culturette EIA. While easy to perform and highly specific, these rapid assays do not appear to be sufficient for accurate diagnosis of CDAD.
ISSN:0095-1137
1098-660X
DOI:10.1128/jcm.37.9.3044-3047.1999