Comparison of three enzyme immunoassays, a cytotoxicity assay, and toxigenic culture for diagnosis of Clostridium difficile-associated diarrhea

Abstract

Enzyme immunoassays (EIAs) based on monoclonal antibodies for the detection of Clostridium difficile toxins have recently been developed for clinical use. The aim of this study was to compare three commercially available EIAs, two for toxin A (Premier C. difficile Toxin A; Meridian, Osi, Elancourt, France; and Vidas C. difficik Toxin A; bioMerieux, Marcy l'Etoile, France) and one for toxins A and B (Cytoclone A + B EIA; Cambridge Biotech Corp., Codiapharm, Evian, France), with a cytotoxicity assay and toxigenic culture for the diagnosis of C. difficie-associated diarrhea (CDAD). The study was performed with 285 fresh stools from 285 patients with suspected CDAD. In case of disagreement, the tests were repeated on a frozen aliquot of the same stool sample, and the patient's chart was reviewed. CDAD diagnosis was established in 55 cases (incidence, 19.3%). The sensitivities and specificities of the methods were, respectively, 92.7 and 100% for the cytotoxicity assay, 96.4 and 99.1% for toxigenic culture, 75.5 and 97.8% for Cytoclone, 65.4 and 99.6% for Premier, and 65.4 and 100% for Vidas. The results were uninterpretable in 3.2% of cases with Cytoclone, 0.3% with Premier, and 2.5% with Vidas. We conclude that the cytotoxicity assay and toxigenic culture remain the best methods for the diagnosis of CDAD even though they lack standardization and require 48 to 96 h to obtain the result. Despite their rapidity and simplicity, EIAs are not sensitive enough to be relied on as the sole laboratory test.

Detection of toxin production in Clostridium difficile strains by three different methods

“…Our results are parallel to this finding. The reported sensitivity and specificity values for other available commercial EIA kits which can detect toxins A and B were between 79.6 and 96.2%, 93.5 and 100%, respectively, and PPV and NPV were between 86.7 and 100% and 95.7 and 99%, respectively [14,18,20,21]. These results are similar to, or a little lower than, those obtained for the Techlab A/B test.…”

A Real‐World Evaluation of Oral Vancomycin for Severe Clostridium difficile Infection: Implications for Antibiotic Stewardship Programs

“…16 The study recruited consecutive hospitalized patients with CDI, which was defined as diarrhea and a positive toxin test for C. difficile using the cytotoxicity assay. 17 Diarrhea was defined as three or more loose bowel movements within a 24-hour period. The study protocol was approved by the institutional review board at the hospital.…”

Clostridium difficile: Recent Epidemiologic Findings and Advances in Therapy

“…40 Results of this test are generally reported within hours or within 1 day. [41][42][43] Culturing stool, if done correctly, has a high degree of sensitivity for identifying the organism, but lacks specificity in relating the presence of C. difficile to disease. Many patients may be colonized with C. difficile and yet remain free of disease.…”

“…In vitro, C. difficile is susceptible to vancomycin; the minimum inhibitory concentration (MIC) for 90% of tested strains (MIC 90 ) is 0.75-2 µg/ml. 41,[49][50][51][52][53][54] A single study found that 3% of C. difficile isolates had intermediate resistance to vancomycin (MIC 4-16 µg/ml), but the clinical implications were not reported, and the in vitro findings have not been reproduced. 55 Since oral vancomycin leads to stool concentrations of up to 3100 µg/ml, 56 results of this study are not likely to be clinically significant.…”