C. DIFF QUIK CHEK

K053572 · Techlab, Inc. · MCB · Apr 26, 2006 · Microbiology

Device Facts

• Record ID: K053572
• Device Name: C. DIFF QUIK CHEK
• Applicant: Techlab, Inc.
• Product Code: MCB · Microbiology
• Decision Date: Apr 26, 2006
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 866.2660
• Device Class: Class 1

Indications for Use

The C. DIFF QUIK CHEK™ test is a rapid membrane enzyme immunoassay for use as a screening test to detect Clostridium difficile antigen, glutamate dehydrogenase, in fecal specimens from persons suspected of having C. difficile disease. The test does not distinguish toxigenic from nontoxigenic strains of C. difficile. With the use of additional tests that detect C. difficile toxins, the test is to be used as an aid in the diagnosis of C. difficile disease. As with other C. difficile tests, results should be considered in conjunction with the patient history. FOR IN VITRO DIAGNOSTIC USE.

Device Story

Rapid membrane enzyme immunoassay for detection of Clostridium difficile glutamate dehydrogenase (GDH) in fecal specimens. Input: diluted fecal sample mixed with antibody-horseradish peroxidase conjugate. Operation: sample-conjugate mixture added to device; GDH binds to conjugate; complexes migrate to membrane; captured by immobilized anti-GDH antibodies in reaction window. Output: visual blue line indicating positive result; control line confirms reagent activity and migration. Used in clinical settings; performed by laboratory personnel. Results aid diagnosis of C. difficile disease when combined with patient history and toxin-detection tests. Benefits: rapid screening for C. difficile presence.

Clinical Evidence

Clinical performance evaluated in 3 studies (n=979). Compared to presumptive bacterial culture, sensitivity was 92.8% and specificity 92.6%. After resolving discrepant results with PCR or other GDH tests, correlation with bacterial culture was 96.9%. Analytical sensitivity is 0.4 ng/mL for GDH. Cross-reactivity testing showed no interference from common intestinal bacteria, pathogens, or viruses. Reproducibility study across three independent labs showed 100% correlation.

Technological Characteristics

Rapid membrane enzyme immunoassay. Materials: immobilized anti-GDH antibodies (test line) and anti-IgG antibodies (control line) on membrane; antibody-horseradish peroxidase conjugate. Principle: lateral flow/membrane capture of antigen-antibody complexes. Visual readout. Standalone device.

Indications for Use

Indicated for screening fecal specimens from persons suspected of having C. difficile disease to detect glutamate dehydrogenase (GDH) antigen. Does not distinguish toxigenic from nontoxigenic strains; intended as an aid in diagnosis when used with additional toxin-detection tests.

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

• Triage® Clostridium difficile Panel (K974881)

Submission Summary (Full Text)

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510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION
DECISION SUMMARY
DEVICE ONLY TEMPLATE

A. 510(k) Number:
K053572

B. Purpose of Submission:
For the detection of the Clostridium difficile common antigen glutamate dehydrogenase in human stool

C. Measurand:
glutamate dehydrogenase antigen

D. Type of Test:
Horizontal flow enzyme immunoassay

E. Applicant:
Tech Lab®, Inc.

F. Proprietary and Established Names:
C. DIFF QUIK CHEK™

G. Regulatory Information:
1. Regulation section:
21 CFR Part 866.2660 Microorganism Differentiation and Identification Device
2. Classification:
I
3. Product Code:
MCB – Antigen, Clostridium difficile.
4. Panel:
83 Microbiology

H. Intended Use:
1. Intended use(s):
The C. DIFF QUIK CHEK™ test is a rapid membrane enzyme immunoassay for use as a screening test to detect Clostridium difficile antigen, glutamate dehydrogenase, in fecal specimens from persons suspected of having C. difficile disease. The test does not distinguish toxigenic from nontoxigenic strains of C. difficile. With the use of additional tests that detect C. difficile toxins, the test is to be used as an aid in the diagnosis of C. difficile disease. As with other C. difficile tests, results should be considered in conjunction with the patient history.
FOR IN VITRO DIAGNOSTIC USE.
2. Indication(s) for use:
The C. DIFF QUIK CHEK™ test is a rapid membrane enzyme immunoassay for use as a screening test to detect Clostridium difficile antigen, glutamate dehydrogenase, in fecal specimens from persons suspected of having C. difficile disease. The test does not distinguish toxigenic from nontoxigenic strains of C. difficile. With the use of additional tests that detect C. difficile toxins, the test is to be used as an aid in the diagnosis of C. difficile disease. As with other C. difficile tests, results should be considered in conjunction with the patient history.

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FOR IN VITRO DIAGNOSTIC USE.

3. Special condition for use statement(s):

For Prescription Use Only

4. Special instrument Requirements:

Not applicable

# I. Device Description:

The C. DIFF QUIK CHEK™ test is a rapid membrane enzyme immunoassay that utilizes antibodies specific for the antigen, glutamate dehydrogenase, of C. difficile. The device contains a Reaction Window with two vertical lines of immobilized antibodies. The test line contains antibodies against C. difficile glutamate dehydrogenase. The control line contains anti-IgG antibodies. The Conjugate consists of antibodies to glutamate dehydrogenase coupled to horseradish peroxidase.

# J. Substantial Equivalence Information:

1. Predicate device name(s):

Triage® Clostridium difficile Panel

2. Predicate K number(s):

K974881

3. Comparison with predicate(s):

| Similarities | | |
| --- | --- | --- |
| Item | Device | Predicates |
| Intended use | an in vitro diagnostic product for the detection of Clostridium difficile in fecal specimens | same |
| Specimen type | fecal specimens | same |
| technology | Enzyme Immunoassay | same |
| Level of skill | Moderately complex | same |
| | Differences | |
| Item | Device | Predicates |
| Limit of detection | 0.8 ng/ml | 2.0 ng/ml |
| Clinical sensitivity | 92.8% CI (88.3% -95.7%) | 91.1% CI (85.8-96.4%) |
| Clinical specificity | 92.6% CI (90.4% - 94.3%) | 93.0% CI (90.7-95.4%) |

# K. Standard/Guidance Document referenced (if applicable):

N/A

# L. Test Principle:

The C. DIFF QUIK CHEK™ test is a rapid membrane enzyme immunoassay that utilizes antibodies specific for the antigen, glutamate dehydrogenase, of C. difficile. The device contains a Reaction Window with two vertical lines of immobilized antibodies. The test line ("T") contains antibodies against C. difficile glutamate dehydrogenase. The control line ("C") contains anti-IgG antibodies. The Conjugate consists of antibodies to glutamate dehydrogenase coupled to horseradish peroxidase. To perform the test, the sample is added to a tube containing a mixture of Diluent and Conjugate. The diluted sample-conjugate mixture is added to the Sample Well and the device is allowed to incubate at room temperature for 15 minutes. During the incubation, any glutamate

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dehydrogenase in the sample binds to the antibody-peroxidase conjugate. The antigen-antibody-conjugate complexes migrate through a filter pad to a membrane where they are captured by the immobilized glutamate dehydrogenase-specific antibodies in the line. The Reaction Window is subsequently washed with Wash Buffer, followed by the addition of Substrate. After a 10 minute incubation period, the "T" reaction is examined visually for the appearance of a vertical blue line on the "T" side of the Reaction Window. A blue line indicates a positive test. A positive "C" reaction, indicated by a vertical blue line on the "C" side of the Reaction Window, confirms that the test is working properly and the results are valid.

## M. Performance Characteristics (if/when applicable):

### 1. Analytical performance:

a. Precision/Reproducibility:

A total of eight fecal specimens, 6 positive and 2 negative were coded to prevent identification and were sent to each of three independent laboratories for analysis using the C. DIFF QUIK CHEK™ test. The results from each laboratory were compared with in-house results. The positive specimens were confirmed to be positive and the negative specimens were confirmed to be negative at each site.

b. Linearity/assay reportable range:

Not applicable

c. Traceability (controls, calibrators, or method):

Not applicable

d. Detection limit:

The limit of detection of the C. DIFF QUIK CHEK™ test is 0.4 ng/mL.

e. Analytical specificity:

Fecal specimens inoculated with the following microorganisms to a final concentration of approximately 10⁸ or higher organisms per mL did not react in the C. DIFF QUIK CHEK™ test:

**Bacteria**: Aeromonas hydrophila, Bacillus cereus, Bacillus subtilis, Bacteroides fragilis, Campylobacter coli, Campylobacter fetus, Campylobacter jejuni, Candida albicans, Clostridium bifermentans, Clostridium butyricum, Clostridium perfringens Type A, Clostridium septicum, Clostridium sordellii (toxigenic and nontoxigenic), Clostridium sporogenes, Enterococcus faecalis, Escherichia coli EIEC, Escherichia coli, Escherichia coli 0157 H7, Escherichia coli ETEC, Klebsiella pneumoniae, Peptostreptococcus anaerobius, Proteus vulgaris, Pseudomonas aeruginosa, Salmonella typhimurium, Shigella dysenteriae, Shigella flexneri, Shigella sonnei, Staphylococcus aureus, Staphylococcus aureus (Cowans), Staphylococcus epidermidis, Vibrio parahaemolyticus, Yersinia enterocolitica.

The following viruses of 10³.³ to 10⁷.⁵ TCID units per 0.2 mL did not react in the C. DIFF QUIK CHEK™ test:

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Viruses: Adenovirus types 1,2,3,5,40,41, Human coronavirus, Coxsackievirus B2,B3,B4,B5, Echovirus 9,11,18,22,33, Enterovirus type 68,69,70,71.

The following substances had no effect on test results when present in feces in the concentrations indicated: mucin (3.5% w/v), human blood (40% v/v), barium sulfate (5% w/v), Imodium® (5% w/v), Kaopectate® (5 mg/mL), Pepto-Bismol® (5% w/v), steric/palmitic acid (fecal fats, 40% w/v), Metronidazole (0.25% w/v), Vancomycin (0.25% w/v)

f. Assay cut-off

The assay cut-off of the C. DIFF QUIK CHEK™ test is 0.8 ng/mL.

## 2. Comparison studies:

a. Method comparison with gold standard:

The C. DIFF QUIK CHEK™ test was compared to the bacterial culture test at two clinical laboratories and in-house at TECHLAB®, Inc.

Specimens included in the evaluation were submitted to the clinical laboratories for routine testing. The presumptive bacterial culture test was performed according to the in-house procedures. The results are shown in Table 1.

Table 1. Summary of clinical performance comparing C. DIFF QUIK CHEK™ test to presumptive bacterial culture

| n=979 | Presumptive Bacterial Culture positive | Presumptive Bacterial Culture negative |
| --- | --- | --- |
| C. DIFF QUIK CHEK™ positive | 206 | 56 |
| C. DIFF QUIK CHEK™ negative | 16 | 701 |
| | | 95% Confidence Limits |
| --- | --- | --- |
| Sensitivity | 92.8% | 88.3% - 95.7% |
| Specificity | 92.6% | 90.4% - 94.3% |
| Predictive Positive Value | 78.6% | 73.1% - 83.3% |
| Predictive Negative Value | 97.8% | 96.3% - 98.7% |
| Correlation | 92.6% | 91.7% - 93.4% |

Discrepant samples were resolved using commercial tests for C. difficile glutamate dehydrogenase in ELISA or membrane test formats, or by a research PCR assay for the detection of C. difficile GDH gene gluD. Twenty-nine of the 56 apparent false positive samples were positive by another GDH test, and were considered true positives. Twenty-seven remained false positive. Thirteen of the 16 apparent false negative samples were negative by another GDH test, and were considered true negatives. Three remained false negative.

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b. Matrix comparison:
Not applicable

3. Clinical studies:

a. Clinical sensitivity:
The C. DIFF QUIK CHEK™ test was compared to the bacterial culture test at two clinical laboratories and in-house at TECHLAB®, Inc. Specimens included in the evaluation were submitted to the clinical laboratories for routine testing. The presumptive bacterial culture test was performed according to the in-house procedures. Of the 979 specimens analyzed by culture, 206 were positive for *Clostridium difficile*. Results are summarized in Tables 1. (See table above)

b. Clinical specificity:
Refer to (a.) above

c. Other clinical supportive data (when a and b is not applicable):
Not applicable

4. Clinical cut-off:
The clinical cut-off of this assay is approximately 0.4 ng/mL. This limit does not vary from solid to liquid/semi-solid stool.

5. Expected values/Reference range: (Interpretive Criteria)

*Clostridium difficile* disease is primarily a nosocomial disease of elderly patients, and the frequency of the disease is dependent on factors such as patient population, type of institution and epidemiology. The reported incidence of *C. difficile* disease in patients with antibiotic-associated diarrhea may range from 5 to 20%, and hospitals may experience rates lower or higher than this range. It is important to consider any test results in conjunction with clinical symptoms because some healthy adults and large numbers of healthy infants (up to 50%) will be positive for *C. difficile* toxin. In addition, *C. difficile* carriage rates of 22 to 32% have been reported in cystic fibrosis patients. Because the *C. DIFF QUIK CHEK™* test detects both toxigenic and non-toxigenic strains of *C. difficile*, the expected values of this test are higher compared to that of any toxin test. A positive result in the *C. DIFF QUIK CHEK™* test confirms the presence of *C. difficile* in a fecal specimen; a negative result indicates the absence of the organism. A positive result should be followed by a toxin-specific test to confirm the presence of toxigenic *C. difficile*. The prevalence of a positive *C. DIFF QUIK CHEK™* test at an independent study site was 18.2% (N=578).

N. Conclusion:
The submitted information in this premarket notification is complete and supports a substantial equivalence decision.

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