IMMUNOCARD TOXIN A

K955859 · Meridian Diagnostics, Inc. · LLH · Apr 18, 1996 · Microbiology

Device Facts

• Record ID: K955859
• Device Name: IMMUNOCARD TOXIN A
• Applicant: Meridian Diagnostics, Inc.
• Product Code: LLH · Microbiology
• Decision Date: Apr 18, 1996
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.2660
• Device Class: Class 1

Indications for Use

The ImmunoCard Toxin A enzyme immunoassay (EIA) is a rapid in vitro qualitative procedure for detecting Clostridium difficile toxin A in human stool. The test can be used to aid in the diagnosis of C. difficile-associated disease. The test may also be used to determine the production of toxin A by C. difficile in BHI broth culture.

Device Story

ImmunoCard Toxin A is a card-based enzyme immunoassay (EIA) for qualitative detection of Clostridium difficile toxin A. Input: human stool specimen or BHI broth culture. Process: stool diluted in sample diluent and enzyme conjugate; applied to card; wash reagent and substrate reagent added; visual inspection for blue color development after 5 minutes. Used in clinical laboratory settings by trained personnel. Output: qualitative positive/negative result. Assists clinicians in diagnosing C. difficile-associated disease by identifying the presence of toxin A.

Clinical Evidence

Clinical evaluation compared ImmunoCard Toxin A to cytotoxin assay (n not specified). Results: relative sensitivity 82.7%, relative specificity 98.2%, relative agreement 96.2%. Comparison against a composite of three reference methods (Toxin A EIA, cytotoxin, and toxigenic culture) showed 85.2% sensitivity, 97.5% specificity, and 96.0% agreement. Reproducibility study conducted across 3 locations over 3 days using strong positive, weak positive, and negative stools showed 100% concordance.

Technological Characteristics

Card-based enzyme immunoassay (EIA). Components include Toxin A ImmunoCards, positive control, enzyme conjugate, sample diluent, wash reagent, and substrate reagent. Detection limit: 3.2 ng toxin A/mL of stool. Qualitative visual readout (blue color development).

Indications for Use

Indicated for patients suspected of having Clostridium difficile-associated disease; used for qualitative detection of C. difficile toxin A in human stool samples.

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

• Tissue culture cytotoxin assay with neutralization using specific anti-toxin

Reference Devices

• Toxin A EIA
• Toxigenic culture

Submission Summary (Full Text)

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K955859

510(k) Summary APR 18 1995
Meridian Diagnostics, Inc.
Cincinnati, Ohio 45244

## APPENDIX A - 510(k) Summary

### E. Identification Information

1) Submitter's Information:

a) Submitter's Name and Address:

Meridian Diagnostics, Inc.
3471 River Hills Dr.
Cincinnati, OH 45244

b) Phone Number: 1-800-543-1980

c) Contact Person: Allen D. Nickol, PhD
Director Scientific & Regulatory Affairs

d) Date Summary Prepared: December 22, 1995

2) Name of Device: ImmunoCard Toxin A. The ImmunoCard Toxin A enzyme immunoassay (EIA) is a rapid *in vitro* qualitative procedure for detecting *Clostridium difficile* toxin A in human stool. The test can be used to aid in the diagnosis of *C. difficile*-associated disease. The test may also be used to determine the production of toxin A by *C. difficile* in BHI broth culture. Classification Name unknown.

3) Predicate Equivalent Device: Tissue culture cytotoxin assay with neutralization using specific anti-toxin.

4) Description of Device: The ImmunoCard Toxin A assay system is a card based EIA for toxin A of *C. difficile*. Each kit contains the following components:

a) Toxin A ImmunoCards (50)
b) Positive Control (0.5ml)
c) Enzyme Conjugate (7.5ml)
d) Sample Diluent (10.0ml)
e) Wash Reagent (28ml)
f) Substrate Reagent (13ml)
g) Transfer Pipets (50)

In brief, the assay is performed by preparing a 1/15 dilution of stool in a mixture of Sample Diluent and Enzyme Conjugate. Using a transfer pipet, 150μl of diluted specimen are then added to each of the lower (sample application) ports on an ImmunoCard. The sample is allowed to enter the card for 5 minutes. Three drops of Wash Reagent are added to each of the upper (Reaction) ports and

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510(k) Summary

Meridian Diagnostics, Inc. Cincinnati, Ohio 45244

allowed to enter the card. Three drops of Substrate Reagent are then added and the card is viewed for visible blue color development after 5 minutes.

5) Intended Use: The ImmunoCard Toxin A enzyme immunoassay (EIA) is a rapid *in vitro* qualitative procedure for detecting *Clostridium difficile* toxin A in human stool. The test can be used to aid in the diagnosis of *C. difficile*-associated disease. The test may also be used to determine the production of toxin A by *C. difficile* in BHI broth culture.

6) Comparison with Predicate Devices: The following comparison of the use, technology, function and performance supports the Statement of Equivalence between the ImmunoCard Toxin A test and cytotoxin testing.

a) Both assays detect toxins of *C. difficile* in patient stools. The ImmunoCard Toxin A test detects enterotoxin (toxin A), the etiologically important toxin. The cytotoxin assay detects toxin B, which is associated with disease through coproduction with toxin A.

b) Both assays are *in vitro* immunoassays. The ImmunoCard Toxin A test is an EIA, while the cytotoxin assay is an antibody-dependent toxin neutralization bioassay.

c) Both tests are performed directly on stool extracts. The ImmunoCard Toxin A test utilizes a Sample Diluent and Enzyme Conjugate, while the cytotoxin assay requires sample dilution, centrifugation and filtration.

d) Both assays yield qualitative results (i.e. positive or negative). The cytotoxin assay can be performed using higher than standard (1/40) dilutions, although the diagnostic significance of this has yet to be determined.

e) Equivalent relative performance was recorded relative sensitivity 82.7%, relative specificity 98.2%, relative agreement 96.2%) when comparing the ImmunoCard Toxin A and cytotoxin tests. When ImmunoCard Toxin A results were compared with concordant result of 3 reference methods (Toxin A EIA, cytotoxin and toxigenic culture), sensitivity, specificity and agreement were 85.2%, 97.5% and 96.0%.

f) These clinical data demonstrate the correlation between

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510(k) Summary

Meridian Diagnostics, Inc.
Cincinnati, Ohio 45244

the two methods, supporting the ImmunoCard Toxin A EIA as being substantially equivalent to the reference cytotoxin method.

## F. Additional Information/Nonclinical Test Results:

1) Sensitivity Limits: The sensitivity of the ImmunoCard Toxin A is approximately 32 pg of toxin A. Allowing for the 1/15 dilution of sample and 150μl assay volume, this equates to 3.2ng toxin A/ml of stool as the ImmunoCard Toxin A limit of detection.

2) Reproducibility: Reproducibility of the ImmunoCard Toxin A test was evaluated by running strong positive, weak positive, and negative stools. Ten specimens were tested in triplicate on each of 3 different days at 3 different locations. No incorrect results were obtained with any test or procedural control.

3) Fresh versus Frozen Stools: The data indicated toxin A is stable in stool for at least 3 days when stored at 4°C. If specimen cannot be tested within this period, freezing the specimen is recommended (≤ -20°C) and does not appreciably alter performance.