VIDAS C. DIFFICILE TOXIN A II ASSAY

K964887 · Biomerieux Vitek, Inc. · LLH · Apr 8, 1997 · Microbiology

Device Facts

• Record ID: K964887
• Device Name: VIDAS C. DIFFICILE TOXIN A II ASSAY
• Applicant: Biomerieux Vitek, Inc.
• Product Code: LLH · Microbiology
• Decision Date: Apr 8, 1997
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.2660
• Device Class: Class 1

Indications for Use

The VIDAS C. difficile Toxin A II assay detects the presence of C. difficile toxin A. It is substantially equivalent to the Meridian Premier C. difficile Toxin A test as an aid in the diagnosis of Clostridium difficile associated disease (CDAD).

Device Story

VIDAS C. difficile Toxin A II assay; qualitative enzyme immunoassay (EIA) for detection of C. difficile toxin A in stool specimens. Automated system processes samples; utilizes VIDAS CDA 2 test and VIDAS CDB (blocking) test for equivocal resolution. Used in clinical laboratory settings by trained personnel. Output provides qualitative result indicating presence or absence of toxin A; assists clinicians in diagnosing CDAD. Benefits include rapid, standardized detection of toxin A to guide patient management.

Clinical Evidence

Clinical performance evaluated against commercially available EIA with discrepant results resolved by cytotoxicity. Study included 1,407 negative and 136 positive specimens. Sensitivity: 94.9% (7 false negatives); Specificity: 99.1% (13 false positives). Equivocal rate: 2.5%, resolved via VIDAS CDB blocking reagents. Precision testing (intra-assay and inter-assay) performed using stool precision pools; CVs ranged from 2.7% to 39.2%. Cross-reactivity observed with C. sordellii and C. difficile toxin-producing strains.

Technological Characteristics

Qualitative enzyme immunoassay (EIA). Automated platform (VIDAS). Includes blocking reagents for equivocal result resolution. Specificity testing against normal human colonic flora. Performance metrics include sensitivity, specificity, and precision (CVs).

Indications for Use

Indicated for use as an aid in the diagnosis of Clostridium difficile associated disease (CDAD) by detecting C. difficile toxin A in stool specimens.

Regulatory Classification

Identification

A microorganism differentiation and identification device is a device intended for medical purposes that consists of one or more components, such as differential culture media, biochemical reagents, and paper discs or paper strips impregnated with test reagents, that are usually contained in individual compartments and used to differentiate and identify selected microorganisms. The device aids in the diagnosis of disease.

Predicate Devices

• Meridian Premier C. difficile Toxin A test

Submission Summary (Full Text)

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K964887
APR - 8 1997

# SUMMARY: Safety and Effectiveness Information for the VIDAS C. difficile Toxin A II assay

The VIDAS C. difficile Toxin A II assay detects the presence of C. difficile toxin A. It is substantially equivalent to the Meridian Premier C. difficile Toxin A test as an aid in the diagnosis of Clostridium difficile associated disease (CDAD). Safety and effectiveness issues for qualitative enzyme immunoassay such as the VIDAS C. difficile Toxin A II assay may include the following:

1. False positive results: In studies comparing the VIDAS C. difficile Toxin A II assay to a commercially available EIA with discrepants resolved by cytotoxicity, of the 1,407 negative specimens there were 13 false positive results for a specificity of 99.1%.

2. False negative results: In studies comparing the VIDAS C. difficile Toxin A II assay to a commercially available EIA with discrepants resolved by cytotoxicity, of the 136 positive specimens there were 7 false negative results for a sensitivity of 94.9%.

3. Equivocal results: The occurrence of equivocals with the VIDAS CDA 2 test was 2.5% in the studies done to demonstrate the performance of the assay. All equivocals were resolved with the use of the VIDAS C. difficile Blocking Reagents in the VIDAS CDB test of the VIDAS C. difficile Toxin A II assay.

4. Invalid results: In the studies done to support the VIDAS C. difficile Toxin A II assay performance claims, there were no invalid VIDAS results.

5. Precision: In the studies done to support the VIDAS C. difficile Toxin A II assay performance claims, the VIDAS CDA 2 test intra-assay precision testing showed coefficients of variation for test values ranging from 2.7 to 31.9% when utilizing stool precision pools. For the VIDAS CDB test intra-assay precision testing showed coefficients of variation for test values ranging from 19.0 to 39.2%. When utilizing the same stool precision pools, the VIDAS CDA 2 test inter-assay precision testing gave coefficients of variation for the test values ranging from 8.6 to 30.8% and coefficients of variation for the test values ranging from 9.1 to 33.4% for the VIDAS CDB test.

6. Assay Specificity: A panel of normal human colonic flora was tested for both cross-reactivity and interference for the VIDAS C. difficile Toxin A II assay. Cross-reactivity and interference was seen with the C. sordellii strain (VPI #9048) when tested at a concentration of 3 x 10⁸ organisms/ml and the C. difficile toxin producing strains (ATCC #9689 and VPI # 10463) when tested at a concentration of 1 x 10⁷ organisms/ml.

The VIDAS C. difficile Toxin A II assay must be used according to package insert instructions when testing for the presence of C. difficile toxin A. Additional information and references may be found in the package insert.