(43 days)
The AmpliVue™ C. difficile Assay is an in vitro diagnostic test for the direct, qualitative detection of the Clostridium difficile Toxin A gene (tcdA) in unformed stool specimens of patients suspected of having Clostridium difficile-associated disease (CDAD). The AmpliVue™ C. difficile Assay is intended for use as an aid in diagnosis of CDAD. The assay utilizes helicase-dependent amplification (HDA) for the amplification of a highly conserved fragment of the Toxin A gene sequence and a self-contained disposable amplicon device that allows for manual evaluation of assay results.
The AmpliVue™ C. difficile Assay combines simple specimen processing, an isothermal amplification technology named helicase-dependent amplification (HDA), and a self- contained disposable amplicon detection device for the detection of Clostridium difficile directly from CDAD-suspected stool specimens. A swab is used to transfer a small amount of specimen into a dilution tube. The diluted sample is then transferred into a sample lysis buffer tube, and the cells are lysed by simple heat treatment. After heat treatment, an aliquot of the lysed sample is added to a reaction tube containing a lyophilized mix of HDA reagents, including primers specific for the amplification of a fragment from the conserved 5' end of the tcdA gene that are located within the PaLoc of toxigenic C. difficile strains. The assay also includes a process control to monitor specimen processing and to confirm the integrity of the assay reagents and cassette detection, as well as to assess for HDA-inhibitors that may be present within the stool specimen. Competitive amplification of the process control DNA also takes place unless inhibitory substances are present or the specimen processing fails. The HDA reaction is asymmetric so that an excess of single stranded DNA is formed from a biotinylated primer present within the reaction mix. The capture probes for each amplicon bind to the corresponding biotinylated single-stranded DNA forming dual labeled amplicons. After completion of the HDA reaction, the reaction tube is transferred to a single-use, disposable cassette for detection. The self-contained cassette is comprised of two individual components: an amplicon cartridge that holds the running buffer and the single 0.2-ml thin wall reaction tube containing the amplified product. The detection chamber houses the amplicon cartridge and a vertical-flow DNA detection strip embedded into the cassette. The DNA detection strip is coated with an anti-FITC antibody and an anti-DNP antibody that serve as the C. difficile test (T2) line and the control (C) line in the assay, respectively. A razor blade and a plastic pin located at the bottom of the detection chamber opens the HDA reaction tube and the running buffer bulb when the handle of the detection chamber is closed. The mixture flows through a fiberglass paper connected to the DNA detection strip that contains a fiberglass pad pre-loaded with streptavidin-conjugated color particles for color visualization. The dual-labeled probe-amplicon hybrid is then detected by the lateral flow strip within the cassette. The bottom line captures the FITC-labeled probe-amplicon and the top line captures the DNPlabeled probe-amplicon. The biotin label attracts the streptavidin-conjugated color particles for visualization and the test result is shown as colored lines visible to the naked eye. Detection of C. difficile DNA is reported when the T2 and C lines are visible through the detection window of the cassette. No detection of C. difficile DNA is reported when only the C line is displayed. The assay is regarded as unresolved when neither line is displayed. The whole procedure takes approximately 75 minutes (Note: The T1 line present on the self-contained cassette is for a triplex assay and is not applicable/used for the AmpliVue C. difficile Assay).
The Quidel AmpliVue™ C. difficile Assay is a qualitative in vitro diagnostic test for the direct detection of the Clostridium difficile Toxin A gene (tcdA) in unformed stool specimens from patients suspected of having Clostridium difficile-associated disease (CDAD). It uses helicase-dependent amplification (HDA) for gene amplification and a manual read of assay results.
Acceptance Criteria and Device Performance:
The document does not explicitly present specific, quantitative acceptance criteria for each performance characteristic in a dedicated table format. However, it provides performance data against which an implicit set of criteria would have been assessed by the regulatory body.
Based on the provided data, the following table summarizes the device's performance, which was implicitly accepted as meeting the regulatory requirements for substantial equivalence. The "Acceptance Criteria" column reflects what would generally be expected for an IVD device of this type, especially given the "Overall Percent Agreement" and 95% Confidence Intervals reported.
| Performance Characteristic | Implicit Acceptance Criteria (Expected/Common) | Reported Device Performance |
|---|---|---|
| Precision (Within-Lab) | High agreement (e.g., ≥95%) for positive and negative controls/samples. Specific high negative agreement often lower but still acceptable within CI. | C. difficile High Negative: 0% (0/48) overall agreement (CI: 0% - 8%) C. difficile Low Positive: 100% (48/48) overall agreement (CI: 91.2% - 100%) C. difficile Moderate Positive: 100% (48/48) overall agreement (CI: 91.2% - 100%) Negative: 100% (48/48) overall agreement (CI: 91.2% - 100%) C. difficile Positive Control: 100% (48/48) overall agreement (CI: 91.2% - 100%) Assay Negative Control: 100% (48/48) overall agreement (CI: 91.2% - 100%) |
| Reproducibility (Multi-Lab) | High agreement (e.g., ≥95%) for positive and negative controls/samples. Specific high negative agreement often lower but still acceptable within CI. | C. difficile High Negative: 80% (72/90) overall agreement (CI: 71% - 87%) C. difficile Low Positive: 100% (89/89) overall agreement (CI: 95% - 100%) C. difficile Moderate Positive: 100% (90/90) overall agreement (CI: 95% - 100%) Negative: 100% (90/90) overall agreement (CI: 95% - 100%) C. difficile Positive Control: 100% (90/90) overall agreement (CI: 95% - 100%) Assay Negative Control: 100% (90/90) overall agreement (CI: 95% - 100%) |
| Analytical Sensitivity (LoD) | LoD defined at 95% positivity for target strains. | ATCC 43255 (Toxinotype 0): 4.2 CFU/Assay CCUG 8864 (Toxinotype X): 0.7 CFU/Assay Final Assay LoD: 4.2 CFU/Assay |
| Analytical Reactivity (Inclusivity) | Detection of a broad range of toxigenic C. difficile strains at specified concentrations. | Detected 24 toxigenic strains (2-3x LoD) across 7 toxinotypes (0, Illb, IIIc, IV, V, VIII, XXIII). |
| Analytical Specificity (Cross-Reactivity) | No cross-reactivity with common enteric pathogens/flora/human DNA at medically relevant concentrations. | No cross-reactivity with 66 bacterial, viral, and yeast microorganisms (at >1.0E+06 CFU/mL or >1.0E+05 PFU/mL) and human DNA. In silico analysis showed no predicted cross-reactivity for C. botulinum. |
| Analytical Specificity (Interfering Substances) | No interference from common substances found in stool specimens at medically relevant concentrations. | None of 34 tested substances (at medically relevant concentrations) interfered with the assay. |
| Method Comparison (vs. Tissue Culture Cytotoxicity Assay) | Performance comparable to predicate/gold standard, with acceptable sensitivity and specificity. | Sensitivity: 93.6% (95% CI: 87.3% - 96.9%) Specificity: 94.1% (95% CI: 92.1% - 95.6%) PPV: 70.3% (95% CI: 62.5% - 77.2%) NPV: 99.0% (95% CI: 97.9% - 99.5%) |
Study Information:
-
Sample sizes used for the test set and data provenance:
- Precision (Within-Lab): 4-member panel (C. difficile positive and negative) tested for 13 days, twice a day by 2 operators. Each category (e.g., C. difficile Low Positive) had 48 results (24 per operator). The samples were artificially prepared by spiking in C. difficile into negative fecal matrix (indicated by "C. difficile High Negative (T2-/C+; 20-80%)", "C. difficile Low Positive (T2+/C+, ≥95%)", etc.). Data provenance is implied to be laboratory-based (in-house).
- Reproducibility (Multi-Lab): Blinded and randomized panel of Clostridium difficile negative and positive samples. Each site tested the panel and assay controls for 5 days in triplicate by 2 operators. Each category (e.g., C. difficile High Negative) had 90 results (30 per site). The samples were artificially prepared by spiking in C. difficile into negative fecal matrix. Data provenance involved 3 test sites, two of which were clinical sites, within the United States.
- Analytical Sensitivity (LoD): Quantified cultures of two C. difficile strains (ATCC 43255, CCUG 8864) serially diluted in negative fecal matrix. Replicates were tested to determine 95% positivity. The exact number of replicates is not stated, but typically 20+ replicates are used per concentration level. Data provenance is implied to be laboratory-based (in-house).
- Analytical Reactivity (Inclusivity): 24 toxigenic strains tested at 2 to 3x LoD. Data provenance: Strains originated from at least five states (USA) and four countries (USA, Belgium, France, Sweden).
- Analytical Specificity (Cross-Reactivity & Interfering Substances): 66 microorganisms and human DNA for cross-reactivity; 34 substances for interference. Data provenance is laboratory-based (in-house).
- Method Comparison: 840 unformed stool samples tested. Data provenance: Four geographically diverse locations within the United States, collected prospectively between January 2012 and October 2012.
-
Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- For the analytical studies (precision, reproducibility, LoD, inclusivity, specificity), the ground truth was established by the preparation methods (e.g., known positive/negative samples, spiked samples, quantified cultures). No external experts were used for these "test sets".
- For the Method Comparison study, the Tissue Culture Cytotoxicity Assay served as the comparator method. While interpretations of this assay might involve expert judgment, the document doesn't specify an expert panel for ground truth determination, as the cytotoxin assay itself is considered a gold standard or a highly reliable reference method for clinical samples in this context. The results from the FDA-cleared molecular device, used to resolve discordant cases, would also rely on the performance characteristics of that device rather than expert consensus on individual cases.
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Adjudication method for the test set:
- Discordant Analysis (Method Comparison Study): For the 835 clinical specimens analyzed by the AmpliVue C. difficile Assay (device) and Tissue Culture Cytotoxicity Assay (comparator):
- 43 discordant specimens (AmpliVue Positive/Tissue Culture Cytotoxin Negative): 37 were positive for C. difficile by an FDA-cleared molecular device, and 6 were negative.
- 7 discordant specimens (AmpliVue Negative/Tissue Culture Cytotoxin positive): 2 were positive for C. difficile by an FDA-cleared molecular device, and 5 were negative.
- This represents a form of 2+1 adjudication, where results from the two primary methods (device and comparator) are adjudicated by a third, FDA-cleared molecular method in cases of discordance.
- Discordant Analysis (Method Comparison Study): For the 835 clinical specimens analyzed by the AmpliVue C. difficile Assay (device) and Tissue Culture Cytotoxicity Assay (comparator):
-
If a multi reader multi case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:
- A MRMC comparative effectiveness study was not performed. This device is a standalone in vitro diagnostic assay with a manual read of results. It does not involve human readers interpreting an AI output or benefiting from AI assistance. The "manual read" refers to visualizing colored lines on a cassette, not a complex interpretation task that would typically involve radiologists or other medical imaging specialists.
-
If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:
- Yes, the performance data presented (analytical and method comparison) represents the standalone performance of the AmpliVue™ C. difficile Assay. Although it has a "manual read" component (visual interpretation of lines), the assay itself is a test-tube-to-cassette system without a human interpretation loop in the way described for AI-assisted diagnostics. The reported sensitivity and specificity values are for the algorithm (the assay) only, reflecting its direct detection capability.
-
The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
- Analytical Studies (Precision, Reproducibility, LoD, Inclusivity, Specificity): Ground truth was based on the known composition of spiked samples or characterized bacterial strains.
- Method Comparison Study: The Tissue Culture Cytotoxicity Assay served as the primary reference standard (ground truth). For discordant results, an FDA-cleared molecular device was used as the adjudicator for confirmatory ground truth.
-
The sample size for the training set:
- The document does not explicitly mention a "training set" in the context of machine learning. This is a traditional in vitro diagnostic device, not an AI/ML-based device. Therefore, the concept of a training set for an algorithm is not directly applicable here. The assay's parameters (e.g., primer sequences, HDA conditions) would have been developed and optimized through iterative laboratory R&D, rather than a formal machine learning training approach on a large dataset.
-
How the ground truth for the training set was established:
- As noted above, there is no explicit "training set" as understood in AI/ML. The development and optimization of the assay's components, such as primer design and reaction conditions, would have been based on established scientific principles in molecular diagnostics and empirical testing against characterized strains and clinical samples to achieve desired performance, not via ground truth establishment for an AI training set.
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DECISION Quidel AmpliVue™ C. difficile Assay 510(k) SUMMARY
A. 510(k) Number:
B. Date of Preparation:
December 10, 2012
C. Purpose for Submission:
To determine substantial equivalence of the AmpliVue™ C. difficile Assay for the qualitative detection of toxigenic Clostridium difficile directly from unformed stool samples.
D. Measurand:
A fragment from the conserved 5' end of the Toxin A (tcdA) gene, located within the PaLoc of toxigenic Clostridium difficile strains.
E. Type of Test:
Qualitative, in vitro diagnostic nucleic acid amplification test; based on the isothermal, helicasedependent amplification (HDA) scheme combined with a manual read of assay results.
F. Applicant:
QUIDEL Corp.
G. Proprietary and Established Names:
AmpliVue™ C. difficile Assay
H. Regulatory Information:
1. Regulation section:
21 CFR 866.3130 - C. difficile Nucleic Acid Amplification Test Assay
10165 McKellar Court • San Diego • California 92121 858.552.1100 • Fax 858.453.4338 www.quidel.com
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QUIDEL®
CORPORATION
-
- Classification: ·
ll
- Classification: ·
-
- Product code:
OZN - Amplification assay for the detection of Clostridium difficile toxin genes from stool specimens of symptomatic patients
- Product code:
-
- Panel:
Microbiology (83)
- Panel:
-
l. Intended Use:
- Intended use(s): 1.
The AmpliVue™ C. difficile Assay is an in vitro diagnostic test for the direct, qualitative detection of the Clostridium difficile Toxin A gene (tcdA) in unformed stool specimens of patients suspected of having Clostridium difficile-associated disease (CDAD). The AmpliVue™ C. difficile Assay is intended for use as an aid in diagnosis of CDAD. The assay utilizes helicase-dependent amplification (HDA) for the amplification of a highly conserved fragment of the Toxin A gene sequence and a self-contained disposable amplicon device that allows for manual evaluation of assay results.
-
- Indication(s) for use:
Same as Intended Use.
- Indication(s) for use:
-
- Special conditions for use statement(s):
For prescription use only.
- Special conditions for use statement(s):
-
- Special instrument requirements:
None, detection is by manual read.
- Special instrument requirements:
J. Device Description:
` The AmpliVue™ C. difficile Assay combines simple specimen processing, an isothermal amplification technology named helicase-dependent amplification (HDA), and a self- contained disposable amplicon detection device for the detection of Clostridium difficile directly from CDAD-suspected stool specimens.
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Image /page/2/Picture/0 description: The image shows the logo for Quidel Corporation. The logo is in black and white and features the word "QUIDEL" in a bold, sans-serif font. Below the word "QUIDEL" is the word "CORPORATION" in a smaller, sans-serif font. The logo is simple and modern.
A swab is used to transfer a small amount of specimen into a dilution tube. The diluted sample is then transferred into a sample lysis buffer tube, and the cells are lysed by simple heat treatment. After heat treatment, an aliquot of the lysed sample is added to a reaction tube containing a lyophilized mix of HDA reagents, including primers specific for the amplification of a fragment from the conserved 5' end of the tcdA gene that are located within the PaLoc of toxigenic C. difficile strains. The assay also includes a process control to monitor specimen processing and to confirm the integrity of the assay reagents and cassette detection, as well as to assess for HDA-inhibitors that may be present within the stool specimen. Competitive amplification of the process control DNA also takes place unless inhibitory substances are present or the specimen processing fails. The HDA reaction is asymmetric so that an excess of single stranded DNA is formed from a biotinylated primer present within the reaction mix. The capture probes for each amplicon bind to the corresponding biotinylated single-stranded DNA forming dual labeled amplicons.
After completion of the HDA reaction, the reaction tube is transferred to a single-use, disposable cassette for detection. The self-contained cassette is comprised of two individual components: an amplicon cartridge that holds the running buffer and the single 0.2-ml thin wall reaction tube containing the amplified product. The detection chamber houses the amplicon cartridge and a vertical-flow DNA detection strip embedded into the cassette. The DNA detection strip is coated with an anti-FITC antibody and an anti-DNP antibody that serve as the C. difficile test (T2) line and the control (C) line in the assay, respectively. A razor blade and a plastic pin located at the bottom of the detection chamber opens the HDA reaction tube and the running buffer bulb when the handle of the detection chamber is closed.
The mixture flows through a fiberglass paper connected to the DNA detection strip that contains a fiberglass pad pre-loaded with streptavidin-conjugated color particles for color visualization. The dual-labeled probe-amplicon hybrid is then detected by the lateral flow strip within the cassette. The bottom line captures the FITC-labeled probe-amplicon and the top line captures the DNPlabeled probe-amplicon. The biotin label attracts the streptavidin-conjugated color particles for visualization and the test result is shown as colored lines visible to the naked eye. Detection of C. difficile DNA is reported when the T2 and C lines are visible through the detection window of the cassette. No detection of C. difficile DNA is reported when only the C line is displayed. The assay is regarded as unresolved when neither line is displayed. The whole procedure takes approximately 75 minutes (Note: The T1 line present on the self-contained cassette is for a triplex assay and is not applicable/used for the AmpliVue C. difficile Assay).
The Quidel AmpliVue C. difficile Assay contains sufficient reagents to process 16 specimens or quality control samples. The kit contains the following:
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| Component | Quantity | Storage |
|---|---|---|
| Detection Cassettes: Each cassette comespreloaded with all required probes and signalamplification solutions necessary to generate a testresult. | 16/kit | 2° to 30°C |
| Dilution Buffer: Ready for use. | 16 tubes/kit 1.8 mL | 2° to 8°C |
| Lysis Buffer: Ready for use. | 16 tubes/kit 1 mL | 2° to 8°C |
| Reaction Tubes: Ready for use. | 16 tubes/kit | 2° to 8°C |
| Amplicon Cartridge: Each cartridge comespreloaded with all solutions required amplification. | 16/kit | 2° to 30°C |
| Flocked Swabs: Ready for use. | 16 swabs/kit | 2° to 30°C |
K. Substantial Equivalence Information:
-
- Predicate device name(s):
Great Basin Scientific Portrait Toxigenic C. Difficile Assay
- Predicate device name(s):
2. Predicate 510(k) number(s):
Great Basin Scientific Portrait Toxigenic C. Difficile Assay - K113358
Comparison with predicate: ന്
| Similarities | ||
|---|---|---|
| Item | Device | Predicate (Great BasinScientific Portrait Toxigenic C.Difficile Assay) |
| Intended Use | The AmpliVue™ C. difficileAssay is an in vitro diagnostictest for the direct, qualitativedetection of the Clostridiumdifficile Toxin A gene (tcdA) inunformed stool specimens ofpatients suspected of having | Portrait Toxigenic C. difficileAssay, a prescription deviceunder 21 CFR Part 801.109that is indicated for thedetection of toxigenicClostridium difficile in humanfecal samples collected frompatients suspected of having |
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. .
・
.
| Similarities | ||
|---|---|---|
| Item | Device | Predicate (Great BasinScientific Portrait Toxigenic C.Difficile Assay) |
| associated disease (CDAD).The AmpliVue™ C. difficileAssay is intended for use asan aid in diagnosis of CDAD.The assay utilizes helicase-dependent amplification(HDA) for the amplification ofa highly conserved fragmentof the Toxin A gene sequenceand a self-containeddisposable amplicondetection device that allowsfor manual evaluation ofassay results. | Clostridium difficile infection(CDI). The test utilizesautomated blocked primerenabled helicase-dependentamplification (bpHDA) todetect toxin gene sequencesassociated with toxinproducing C. difficile. ThePortrait Toxigenic C. difficileAssay is intended as an aid inthe diagnosis of CDI. | |
| Specimen | Unformed stool | Same |
| Assay time | 75-90 min | same |
| Test Cartridge | Disposable, single-use, multi-chambered fluidic cartridge. | Same |
| Technological principle | Nucleic acid amplification | Same |
| Assay technique | Isothermal, helicase-dependent nucleic acidamplification | Same |
| Differences | ||
|---|---|---|
| Item | Device | Predicate |
| Analyte | Toxin A gene ( tcdA ) | Toxin B gene ( tcdB ) |
| Detectiontechnique/instrument | The HDA reaction generates abiotinylated amplicon forboth the target ( tcdA ) and theinternal control. Capture | Amplification primers arebiotin-labeled primers andhybridized to probesimmobilized on a silicon chip. |
| Differences | ||
| Item | Device | Predicate |
| probes specifically bind to thecorresponding biotinylatedsingle-stranded DNA formingdual labeled amplicons. Thereaction tube containing thismixture is transferred to asingle-use, disposablecassette for detection. Themixture flows through afiberglass paper connected tothe DNA detection strip thatcontains a fiberglass pad pre-loaded with streptavidin-conjugated color particles forcolor visualization. The dual-labeled probe-ampliconhybrid is then detected by thelateral flow strip within thecassette. The bottom linecaptures the FITC-labeledprobe-amplicon and the topline captures the DNP-labeledprobe-amplicon. The biotinlabel attracts thestreptavidin-conjugated colorparticles for visualization andthe test result is shown ascolored lines visible to thenaked eye. | Incubation with anti-biotinantibody conjugated to theHRP with TMB allowsvisualization by PortraitAnalyzer | |
| Detection method | Manual | Automated |
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L. Standard/Guidance Document Referenced (if applicable):
"Establishing the Performance Characteristics of In Vitro Diagnostic Devices for the Detection of Clostridium difficile." DRAFT Guidance - November 29, 2010
.
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M. Test Principle:
The AmpliVue™ C. difficile Assay combines simple specimen processing, an isothermal amplification technology named helicase-dependent amplification (HDA), and a self- contained disposable amplicon detection device for the detection of Clostridium difficile directly from CDAD-suspected stool specimens.
A swab is used to transfer a small amount of specimen into a dilution tube. The diluted sample is then transferred into a sample lysis tube and the cells are lysed by simple heat treatment. After heat treatment an aliquot of the lysed sample is added to a reaction tube containing lyophilized mix of HDA reagents including primers specific for the amplification of a fragment from the conserved 5' end of the tcdA gene, located within the PaLoc of toxigenic C. difficile strains. The assay also includes a process control to monitor sample processing and to confirm the integrity of the assay reagents and cassette detection as well as assay for HDA-inhibitors that may be present within the diarrheal sample. After completion of the HDA reaction tube is transferred to a disposable lateral flow detection cassette for rapid detection with test result displayed as test and/or control lines in the window of the detection cassette. The whole procedure takes approximately 75 minutes, depending on the number of specimens processed.
N. Performance Characteristics (if/when applicable):
1. Analytical performance:
a. Precision/Reproducibility:
Precision: For the Precision/Within Laboratory Repeatability study, a blinded four-member panel consisting of C. difficile positive and negative sample was tested by two operators, twice a day using a single assay lot of AmpliVue C. difficile Assay for thirteen (13) days.
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| Category | Operator #1 | Operator #2 | Overall Percent Agreement | 95% Confidence Interval | |||
|---|---|---|---|---|---|---|---|
| #expectedresults/# tested | % Agreement | #expectedresults/# tested | % Agreement | ||||
| C. difficile High Negative(T2-/C+; 20-80%) | 0/24 | 0% | 0/24 | 0% | 0/48 | 0% | 0% - 8% |
| C. difficile Low Positive(T2+/C+, ≥95%) | 24/24 | 100% | 24/24 | 100% | 48/48 | 100% | 91.2% - 100% |
| C. difficile Moderate Positive(T2+/C+, ≥95%) | 24/24 | 100% | 24/24 | 100% | 48/48 | 100% | 91.2% - 100% |
| Negative(T2-/C+, 100%) | 24/24 | 100% | 24/24 | 100% | 48/48 | 100% | 91.2% - 100% |
| C. difficile Positive Control | 24/24 | 100% | 24/24 | 100% | 48/48 | 100% | 91.2% - 100% |
| Assay Negative Control | 24/24 | 100% | 24/24 | 100% | 48/48 | 100% | 91.2% - 100% |
- September 1999
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Reproducibility: In order to confirm the reproducibility of the AmpliVue™ C. difficile Assay a blinded and randomized study panel containing Clostridium difficile negative and positive samples were tested at three (3) test sites, two of which were clinical sites. Each site tested a reproducibility panel and assay controls for five (5) days in triplicate. The testing was done by two operators at each site. Each operator ran the panel once a day using one lot of AmpliVue™ C. difficile Assay.
| Category | Site #1 | Site #2 | Site #3 | Overall PercentAgreement | 95% ConfidenceInterval | ||||
|---|---|---|---|---|---|---|---|---|---|
| #expectedresults/#tested | % Agreement | #expectedresults/#tested | % Agreement | #expectedresults/# tested | % Agreement | ||||
| C. difficile HighNegative | 25/30 | 83% | 23/30 | 77% | 24/30 | 80% | 72/90 | 80% | 71% - 87% |
| C. difficile LowPositive | 30/30 | 100% | 29/29 | 100% | 30/30 | 100% | 89/89* | 100% | 95% - 100% |
| C. difficileModerate Positive | 30/30 | 100% | 30/30 | 100% | 30/30 | 100% | 90/90 | 100% | 95% - 100% |
| Negative | 30/30 | 100% | 30/30 | 100% | 30/30 | 100% | 90/90 | 100% | 95% - 100% |
| C. difficile PositiveControl | 30/30 | 100% | 30/30 | 100% | 30/30 | 100% | 90/90 | 100% | 95% - 100% |
| Assay NegativeControl | 30/30 | 100% | 30/30 | 100% | 30/30 | 100% | 90/90 | 100% | 95% - 100% |
| Lot# | CLIN-005 |
Note: One (1) sample was invalid.
b. Linearity/assay reportable range:
N/A
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Controls: C.
The AmpliVue C. difficile assay incorporates a process control which is included in the lysis buffer tube and is used to monitor sample processing and evaluates the presence of inhibitory substances. The process control confirms the integrity of assay reagents and cassette detection. Additional controls are performed in accordance with end user laboratory guidelines and requirements.
Detection limit: d.
The analytical sensitivity (limit of detection or LoD) of the Quidel AmpliVue C. difficile Assay was determined using quantified (CFU/mL) cultures of two C. difficile strains (ATCC 43255 {toxinotype 0} and CCUG 8864 {toxinotype X}) serially diluted in a negative fecal matrix. Analytical sensitivity (LoD) is defined as the lowest concentration at which 95% of all replicates tested positive.
| Strain | Toxinotype | LoD (CFU/ Assay) |
|---|---|---|
| ATCC 43255 | 0 | 4.2 |
| CCUG 8864 | × | 0.7 |
The final assay LoD is defined as the higher of the two strain concentrations where 95% positivity was observed. The final assay LoD is 4.2 CFU/assay.
Analytical Reactivity (Inclusivity) e.
Twenty-four toxigenic strains for C. difficile were tested at 2 to 3x LoD in negative specimen matrix using three (3) AmpliVue C. difficile assay lots. Strains were reported to originate from at least five states and four countries (USA, Belgium, France and Sweden). Seven (7) toxinotypes were represented: 0, Illb, IIIc, IV, V, VIII and XXIII. The analytical reactivity (inclusivity) testing conducted demonstrated that the AmpliVue C. difficile assay can detect a broad range of toxigenic Clostridium difficile strains.
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Analytical specificity: f.
Cross Reactivity
The analytical specificity of the Quidel AmpliVue C. difficile Assay was evaluated by testing a panel consisting of sixty-six (66) bacterial, viral and yeast microorganisms and human DNA representing common enteric pathogens, flora or nucleic acid commonly present in the intestine. Microorganisms or nucleic acid was mixed with pooled negative matrix and tested directly or in the presence of 2 to 3x LoD level of C. difficile for cross reactivity and microbial interference, respectively. Bacteria were tested at concentrations greater than 1.0E+06 CFU/mL and viruses at greater than 1.0E+05 PFU/mL. In addition, in silico analysis showed that the AmpliVue C. difficile Assay had no predicted cross-reactivity for C. botulinum. The results of this study demonstrate that the AmpliVue C. difficile Assay does not cross react with medically relevant levels of viruses or bacteria found in stool specimens.
Interfering Substances
Two toxigenic strains of C. difficile (ATCC 43255, toxinotype 0; CCUG 8864, toxinotype X) were evaluated against a test panel consisting of thirty-four substances found in stool specimens. Substances were introduced into the assay dilution tubes at concentrations which were medically relevant. Each of the strains was tested for each substance. None of the substances tested were found to interfere with the AmpliVue C. difficile Assay.
Assay cut-off: g.
N/A
-
- Comparison studies:
Method comparison with predicate device: a.
- Comparison studies:
The performance of the AmpliVue C. difficile Assay was evaluated at four geographically diverse locations within the United States between January 2012 and October 2012. Eight hundred and forty (840) samples were tested by both the AmpliVue C. difficile Assay and the Tissue Culture Cytotoxicity Assay. One specimen (0.1%) was indeterminate in the cytotoxin assay due to toxicity in the antitoxin well. Four specimens (0.5%) were invalid in the AmpliVue C. difficile Assay when initially tested. Three (3) of these specimens yielded valid results (all were negative) when retested according to the AmpliVue C. difficile Assay's instructions for use. One (1) specimen remained invalid upon repeat testing. The data below is based on the initial result for the eight hundred and thirty-five (835) specimens.
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Image /page/11/Picture/0 description: The image shows the logo for Quidel Corporation. The logo is in black and white and features the word "QUIDEL" in large, bold letters. Below the word "QUIDEL" is the word "CORPORATION" in smaller letters. The logo is simple and professional.
| Tissue CultureCytotoxin | 95% CI | |||||||
|---|---|---|---|---|---|---|---|---|
| POS | NEG | Total | Sensitivity | 93.6% | 87.3% | 96.9% | ||
| AmpliVue C. difficile | POS | 102 | 43* | 145 | Specificity | 94.1% | 92.1% | 95.6% |
| NEG | 7** | 683 | 690 | ppv | 70.3% | 62.5% | 77.2% | |
| Total | 109 | 726 | 835 | npv | 99.0% | 97.9% | 99.5% |
- Of these forty three (43) discordant specimens (AmpliVue Positive/Tissue Culture Cytotoxin Negative) reported, thirty-seven (37) were positive for C. difficile by a FDA-cleared molecular device, and six (6) were negative.
** Of these seven (7) discordant specimens (AmpliVue Negative/Tissue Culture Cytotoxin positive) reported, two (2) were positive for C. difficile by a FDA-cleared molecular device, and five (5) were negative.
The distribution of positive specimens is parsed by gender and age below (incidence based on results from the AmpliVue C. difficile Test):
| Male | Female | Total | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Age | n | AmpliVue+ | % | n | AmpliVue+ | % | n | AmpliVue+ | % |
| <2 | 14 | 6 | 42.9% | 12 | 2 | 16.7% | 26 | 8 | 30.8% |
| ≥2 and <12 | 45 | 9 | 20.0% | 27 | 6 | 22.2% | 72 | 15 | 20.8% |
| ≥12 and <18 | 21 | 2 | 9.5% | 24 | 3 | 12.5% | 45 | 5 | 11.1% |
| ≥18 and ≤21 | 14 | 3 | 21.4% | 5 | 0 | 0.0% | 19 | 3 | 15.8% |
| >21 and ≤59 | 166 | 25 | 15.1% | 167 | 26 | 15.6% | 333 | 51 | 15.3% |
| ≥60 | 134 | 25 | 18.7% | 206 | 38 | 18.4% | 340 | 63 | 18.5% |
| Total | 394 | 70 | 17.8% | 441 | 75 | 17.0% | 835 | 145 | 17.4% |
-
b. Matrix comparison:
N/A -
- Clinical studies:
- a. Clinical Sensitivity:
N/A
- b. Clinical specificity:
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QUIDEL
CORPORATION
N/A
-
Other clinical supportive data (when a. and b. are not applicable): ن
N/A -
Clinical cut-off: ধ:
N/A -
- Expected values/Reference range:
N/A
- Expected values/Reference range:
O. Proposed Labeling:
The labeling is per the requirements of 21 CFR Part 809.10.
P. Conclusion:
Quidel has submitted this 510(k) in accordance with the requirements of SMDA 1990 and 21 CFR 807.92. This summary of 510(k) safety and effectiveness information provides the necessary detail for a determination of substantial equivalence for the Quidel AmpliVue™ C. difficile Assay.
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Decision Summary, K123355
This 510(k) was reviewed under OIR's Pilot Triage Program. This program represents an internal workload management tool intended to reduce internal FDA review resources for 510(k) applications that are of good quality upon receipt by FDA.
The information in the 510(k) is complete and supports a substantial equivalence (SE) determination. Please refer to the applicant's 510(k) summary for a summary of the information that supports this SE determination.
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DEPARTMENT OF HEALTH & HUMAN SERVICES
Image /page/14/Picture/1 description: The image shows the logo for the U.S. Department of Health & Human Services. The logo consists of a circular seal with the text "DEPARTMENT OF HEALTH & HUMAN SERVICES - USA" arranged around the perimeter. Inside the circle is a stylized image of an eagle, represented by a series of curved lines, symbolizing the department's role in protecting and promoting the health and well-being of the nation.
Public Health Service
Food and Drug Administration 10903 New Hampshire Avenue Document Control Center - WO66-G609 Silver Spring, MD 20993-002
Quidel Corporation Mr. Ron H. Lollar 10165 McKellar Court San Diego, California 92121
EC 1 3 2012
Re: K123355
Trade/Device Name: Regulation Number: Regulation Name: Regulatory Class: Product Code: Dated: Received:
AmpliVue™ C. difficile Assay 21 CFR 866.3130 C. Difficile Nucleic Acid Amplification Test Assay Class II OZN October 26, 2012 November 6, 2012
Dear Mr. Lollar:
We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration.
If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.
Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801); medical device reporting (reporting of medical device-related adverse events) (21 CFR 803); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820); and if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.
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Page 2 - Ron H. Lollar
If you desire specific advice for your device on our labeling regulation (21 CFR Parts 801 and 809), please contact the Office of In Vitro Diagnostics and Radiological Health at (301) 796-5450. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR Part 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to http://www.fda.gov/MedicalDevices/Safety/ReportaProblem/default.htm for the CDRH's Office
of Surveillance and Biometrics/Division of Postmarket Surveillance.
You may obtain other general information on your responsibilities under the Act from the Division of Small Manufacturers, International and Consumer Assistance at its toll-free number (800) 638-2041 or (301) 796-7100 or at its Internet address http://www.fda.gov/cdrl/industry/support/index.html.
Sincerely yours,
Sally A. Hojvat
Sally A. Hojvat, M.Sc., Ph.D. Director Division of Microbiology Devices Office of In Vitro Diagnostics and Radiological Health Center for Devices and Radiological Health
Enclosure
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510(k) Number K123355:
Device Name: AmpliVue™ C. difficile Assay
Indication for Use:
The AmpliVue™ C. difficile assay is an in vitro diagnostic test for the direct, qualitative detection of the Clostridium difficile Toxin A gene (tcdA) in unformed stool specimens of patients suspected of having Clostridium difficile-associated disease (CDAD). The AmpliVue™ C. difficile assay is intended for use as an aid in diagnosis of CDAD. The assay utilizes helicase-dependent amplification (HDA) for the amplification of a highly conserved fragment of the Toxin A gene sequence and a self-contained disposable amplification detection device that allows for manual evaluation of assay results.
Prescription Use X (Part 21 CFR 801 Subpart D)
AND/OR
Over-The-Counter Use (21 CFR 801 Subpart C)
(PLEASE DO NOT WRITE BELOW THIS LINE-CONTINUE ON ANOTHER PAGE IF NEEDED
Concurrence of CDRH, Office of Device Evaluation (ODE)
Soy at
Division Sign-Off
Office of In Vitro Diagnostic Device Evaluation and Safety
K 123355 510(k)
§ 866.3130 Clostridium difficile toxin gene amplification assay.
(a)
Identification. AClostridium difficile toxin gene amplification assay is a device that consists of reagents for the amplification and detection of target sequences inClostridium difficile toxin genes in fecal specimens from patients suspected of havingClostridium difficile infection (CDI). The detection of clostridial toxin genes, in conjunction with other laboratory tests, aids in the clinical laboratory diagnosis of CDI caused byClostridium difficile. (b)
Classification. Class II (special controls). The special controls are set forth in FDA's guideline document entitled: “Class II Special Controls Guideline: Toxin Gene Amplification Assays for the Detection ofClostridium difficile; Guideline for Industry and Food and Drug Administration Staff.” See § 866.1(e) for information on obtaining this document.