(89 days)
The RIDA® GENE Norovirus GI/GII assay, performed on the Applied Biosystems® 7500 Fast Dx System, is a real-time RT-PCR in vitro diagnostic test for the qualitative detection and differentiation of norovirus genogroup I (GI) and II (GII) RNA from raw or unpreserved stool specimens collected from individuals with signs and symptoms of acute gastroenteritis.
The RIDA®GENE Norovirus GUGII assay is intended for use as an aid in the differential diagnosis of norovirus genogroup I and II infections in patients symptomatic for gastroenteritis in conjunction with clinical evaluation. laboratory findings, and epidemiological information. The assay aids in the detection and identification of norovirus infections as the cause of acute gastroenteritis in sporadic cases as well as in the context of outbreaks.
Negative results do not preclude a norovirus infection and should not be used as the sole basis for diagnosis.
The RIDA®GENE Norovirus GI/GII assay, performed on the Applied Biosystems® 7500 Fast Dx System, is a real-time RT-PCR in vitro diagnostic test for the qualitative detection and differentiation of norovirus genogroup I (GI) and II (GII) RNA in human stool specimens. The assay also detects an internal control RNA (ICR, bacteriophage MS2) that is added to each sample prior to extraction. Sample preparation and amplification/real-time detection are completed on separate instruments. Each sample is pre-treated prior to extraction and sample processing is completed on the bioMérieux NucliSENS® easyMAG® instrument with bioMérieux NucliSENS® Nucleic Acid Extraction Reagents according to the manufacturer's instructions. The ICR serves to monitor inhibitors in the extracted specimen; it assures that adequate amplification has taken place and confirms that the nucleic acid extraction was sufficient.
Following processing, either extracted nucleic acids or extracted negative control (NC) or positive control (PC) material is added to the Master-Mix. The assay is performed on an Applied Biosystems® 7500 FAST Dx System. The detection is performed in a one-step real-time RT-PCR format where the reverse transcription is followed by the PCR in the same reaction tube under optimized conditions. The isolated RNA is transcribed into cDNA by a reverse transcriptase. Gene fragments specific for norovirus GI and GII are subsequently amplified by real-time PCR. The amplified targets (ORF1/ORF2 conserved junction region) are detected with hydrolysis (TaqMan®) probes, which are labeled at one end with a quencher and at the other end with a fluorescent reporter dye (fluorophore). In the presence of a target, the probe(s) hybridize to it and during the extension step the Taqpolymerase breaks the reporter-quencher proximity. Upon excitation by the Applied Biosystems® 7500 FAST Dx's halogen light source, the reporter emits a distinct fluorescent signal which is detected by the optical unit of the Applied Biosystems® 7500 FAST Dx System. Hence, depending on the target sequence present (genogroup GI, GII or both), one, two or none of the reporters on the norovirus specific probes emits light to be detected by the instrument. Fluorophores are chosen in a way that their excitation and emission wavelengths do not overlap and signals are readily discriminated by the software. The fluorescence signal increases with the amount of formed amplicons.
Here's an analysis of the RIDA®GENE Norovirus GI/GII assay's acceptance criteria and the study proving it meets them, based on the provided text:
Acceptance Criteria and Device Performance for RIDA®GENE Norovirus GI/GII Assay
1. Table of Acceptance Criteria and Reported Device Performance
The document does not explicitly state pre-defined acceptance criteria (e.g., "PPA must be > X%, NPA must be > Y%") for clinical performance. Instead, it presents the results of the clinical study which are intended to demonstrate substantial equivalence to the predicate device. The values reported therefore are the "reported device performance."
However, based on the nature of diagnostic molecular assays, common acceptance metrics are Positive Percent Agreement (PPA) and Negative Percent Agreement (NPA) with a reference method. The clinical study results are presented against these metrics.
| Metric (Implied Acceptance Criterion) | Reported Device Performance (Norovirus GI) | Reported Device Performance (Norovirus GII) |
|---|---|---|
| Clinical Performance | ||
| Positive Percent Agreement (PPA) | 91.8 % (95% CI: 81.9 % – 97.3 %) | 94.7 % (95% CI: 90.9 % – 97.2 %) |
| Negative Percent Agreement (NPA) | 99.1 % (95% CI: 98.2% – 99.6 %) | 98.0 % (95% CI: 96.7 % – 98.8 %) |
| Analytical Performance | ||
| Reproducibility (GI. low positive CV%) | 2.6 % (across 3 sites) | N/A (low positive for GII is 2.5%) |
| Reproducibility (GII low positive CV%) | N/A (low positive for GI is 2.6%) | 2.5 % (across 3 sites) |
| Limit of Detection (LoD) | 6.5 x 10^5 RNA copies/g stool | 2.5 x 10^5 RNA copies/g stool |
| Analytical Specificity | 100% (against 69 organisms tested) | 100% (against 69 organisms tested) |
| Analytical Reactivity | Detected all 8 GI subgroups tested | Detected all 16 GII subgroups tested |
| Absence of Interference | No interference observed from 11 substances | No interference observed from 11 substances |
| No Carry-over/Cross-contamination | Demonstrated no carry-over/cross-contamination | Demonstrated no carry-over/cross-contamination |
Note: The document only provides actual performance values rather than specified acceptance thresholds. The "acceptance criteria" here are implied to be that the performance is sufficiently good to demonstrate substantial equivalence.
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size for Clinical (Test) Set: A total of 1019 raw or unpreserved stool specimens were used for the clinical performance study.
- This included 769 samples collected prospectively from February 2014 to April 2015. Out of these, 50 could not be used, leaving 719 samples.
- Additionally, 332 retrospectively collected samples from various previous outbreaks were tested from September 2016 to April 2017. Out of these, 300 provided valid results.
- The sum (719 + 300) does not exactly equal 1019, suggesting either some overlap or different accounting for invalid samples. However, the document clearly states "A total of 1019 study specimens consisted of raw or unpreserved stool specimens".
- Data Provenance:
- Country of Origin: United States (multi-center study conducted at four institutions in the U.S.).
- Retrospective or Prospective: A combination of prospective (769 samples) and retrospective (332 samples) data was used.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications
The ground truth for the clinical test set was established by a "composite reference method performed at the CDC (Atlanta, GA)."
- Number of Experts: Not specified. The reference method involved specialized laboratory testing at the CDC, but it doesn't state if expert adjudication (e.g., individual opinion or consensus) was part of establishing the final composite reference result beyond the laboratory procedure itself.
- Qualifications of Experts: Not specified beyond the fact that the testing was performed at the CDC, implying highly qualified laboratory personnel. The reference method itself ("conventional RT-PCR followed by bi-directional sequencing") is a highly technical and objective method, rather than a subjective expert interpretation.
4. Adjudication Method for the Test Set
The ground truth was a "composite comparator method that consisted of a combination of Center for Disease Control and Prevention (CDC) RT-PCR assays and bi-directional sequencing for norovirus." This describes a laboratory-based, objective reference standard, not a human consensus or adjudication process in the traditional sense that might be seen in imaging studies (e.g., "2+1" rule for radiologists). The final determination would have been based on the results of these specialized molecular tests.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not performed. This study focuses on the standalone performance of the RIDA®GENE Norovirus GI/GII assay against a laboratory reference standard. It does not involve human readers interpreting results, nor does it compare human performance with and without AI assistance.
6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study
Yes, a standalone performance study was conducted. The document describes the "Clinical Performance" of the RIDA®GENE Norovirus GI/GII assay as a diagnostic test operating on its own (after sample preparation and instrument processing) to detect and differentiate norovirus GI and GII RNA. The results (PPA and NPA) are for the device's performance against the reference method without human interpretation of the assay's output influencing the direct comparison.
7. Type of Ground Truth Used for Clinical Test Set
The ground truth used for the clinical test set was a composite reference method consisting of:
- Conventional RT-PCR assays
- Bi-directional sequencing for both Region C and Region D of norovirus.
This is a laboratory-based, highly sensitive, and specific molecular gold standard.
8. Sample Size for the Training Set
The document does not specify the sample size used for the training set. This is a common characteristic of medical device submissions for molecular assays like RT-PCR kits, where the 'training' of the assay is typically based on optimizing primers, probes, and reaction conditions during development, using a variety of known positive and negative controls and clinical samples to establish analytical performance characteristics (like LoD, inclusivity, exclusivity). It's not a machine learning model that undergoes explicit "training" with a labeled dataset in the same way.
9. How the Ground Truth for the Training Set Was Established
As noted above, a distinct "training set" with a formally established ground truth in the context of machine learning is not described. For the development and optimization of the assay:
- Analytical Sensitivity (LoD): Established using dilution series of native fecal samples (genogroup I and II) where norovirus RNA copy numbers were determined by standard curves using quantified transcripts. The genogroup of native samples was determined by conventional RT-PCR followed by bi-directional sequencing.
- Analytical Specificity (Cross-Reactivity): Evaluated against a panel of 69 known organisms (bacteria, fungus, viruses, parasites) whose identity was known.
- Analytical Reactivity (Inclusivity): Evaluated against 24 known norovirus genotypes (GI and GII strains) at low and high concentrations.
Thus, the ground truth for establishing analytical performance characteristics (which inform the assay's design and "training") relies on known, characterized isolates/strains and quantified reference materials, often confirmed by gold-standard molecular methods like sequencing.
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Public Health Service
August 21, 2017
Food and Drug Administration 10903 New Hampshire Avenue Document Control Center - WO66-G609 Silver Spring, MD 20993-0002
R-Biopharm AG Patricia Meinhardt Vice President, Regulatory Affairs 870 Vossbrink Drive Washington, MO 63090
Re: K171511
Trade/Device Name: RIDA®GENE Norovirus GI/GII Regulation Number: 21 CFR 866.3990 Regulation Name: Gastrointestinal Microorganism Multiplex Nucleic Acid Based Assay Regulatory Class: Class II Product Code: PIO. OOI Dated: May 23, 2017 Received: May 24, 2017
Dear Ms. Meinhardt:
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. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.
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 and Part 809); 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
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electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.
If you desire specific advice for your device on our labeling regulation (21 CFR Part 801), please contact the Division of Industry and Consumer Education at its toll-free number (800) 638-2041 or (301) 796-7100 or at its Internet address
http://www.fda.gov/MedicalDevices/Resourcesfor You/Industry/default.htm. Also, please note the regulation entitled. "Misbranding by reference to premarket notification" (21CFR 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 Industry and Consumer Education at its toll-free number (800) 638-2041 or (301) 796-7100 or at its Internet address
http://www.fda.gov/MedicalDevices/ResourcesforYou/Industry/default.htm.
Sincerely,
Steven R. Gitterman -S
for
Uwe Scherf, 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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Indications for Use
510(k) Number (if known) K171511
Device Name RIDA®GENE Norovirus GI/GII
Indications for Use (Describe)
The RIDA® GENE Norovirus GI/GII assay, performed on the Applied Biosystems® 7500 Fast Dx System, is a real-time RT-PCR in vitro diagnostic test for the qualitative detection and differentiation of norovirus genogroup I (GI) and II (GII) RNA from raw or unpreserved stool specimens collected from individuals with signs and symptoms of acute gastroenteritis.
The RIDA®GENE Norovirus GUGII assay is intended for use as an aid in the differential diagnosis of norovirus genogroup I and II infections in patients symptomatic for gastroenteritis in conjunction with clinical evaluation. laboratory findings, and epidemiological information. The assay aids in the detection and identification of norovirus infections as the cause of acute gastroenteritis in sporadic cases as well as in the context of outbreaks.
Negative results do not preclude a norovirus infection and should not be used as the sole basis for diagnosis.
| Type of Use (Select one or both, as applicable) | |
|---|---|
| ------------------------------------------------- | -- |
X | Prescription Use (Part 21 CFR 801 Subpart D)
Over-The-Counter Use (21 CFR 801 Subpart C)
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510(k) Summary
| Submitted by: | R-Biopharm AGAn der neuen Bergstraße 1764297 DarmstadtGermany |
|---|---|
| Contact: | Patricia MeinhardtR-Biopharm Inc.870 Vossbrink DriveWashington, MO 63090Phone: 877-789-3033 |
| Date of Preparation: | August 11, 2017 |
| Device: | |
| Trade name: | RIDA®GENE Norovirus GI/GII |
| Common name: | RIDA®GENE Norovirus GI/GII assay |
| Type test: | Real-time RT-PCR intended for the in vitroqualitative detection and differentiation ofnorovirus genogroup I (GI) and II (GII) RNA |
| Regulation number: | 21 CFR 866.3990 - Gastrointestinal microorganismmultiplex nucleic acid - based assay |
| Product code: | PIQ, OOI |
| Predicate device: | Cepheid Xpert® Norovirus; (K142501) |
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Device Description
The RIDA®GENE Norovirus GI/GII assay, performed on the Applied Biosystems® 7500 Fast Dx System, is a real-time RT-PCR in vitro diagnostic test for the qualitative detection and differentiation of norovirus genogroup I (GI) and II (GII) RNA in human stool specimens. The assay also detects an internal control RNA (ICR, bacteriophage MS2) that is added to each sample prior to extraction. Sample preparation
and amplification/real-time detection are completed on separate instruments. Each sample is pre-treated prior to extraction and sample processing is completed on the bioMérieux NucliSENS® easyMAG® instrument with bioMérieux NucliSENS® Nucleic Acid
Extraction Reagents according to the manufacturer's instructions. The ICR serves to monitor inhibitors in the extracted specimen; it assures that adequate amplification has taken place and confirms that the nucleic acid extraction was sufficient.
Following processing, either extracted nucleic acids or extracted negative control (NC) or positive control (PC) material is added to the Master-Mix. The assay is performed on an Applied Biosystems® 7500 FAST Dx System. The detection is performed in a one-step real-time RT-PCR format where the reverse transcription is followed by the PCR in the same reaction tube under optimized conditions. The isolated RNA is transcribed into cDNA by a reverse transcriptase. Gene fragments specific for norovirus GI and GII are subsequently amplified by real-time PCR. The amplified targets (ORF1/ORF2 conserved junction region) are detected with hydrolysis (TaqMan®) probes, which are labeled at one end with a quencher and at the other end with a fluorescent reporter dye (fluorophore). In the presence of a target, the probe(s) hybridize to it and during the extension step the Taqpolymerase breaks the reporter-quencher proximity. Upon excitation by the Applied Biosystems® 7500 FAST Dx's halogen light source, the reporter emits a distinct fluorescent signal which is detected by the optical unit of the Applied Biosystems® 7500 FAST Dx System. Hence, depending on the target sequence present (genogroup GI, GII or both), one, two or none of the reporters on the norovirus specific probes emits light to be detected by the instrument. Fluorophores are chosen in a way that their excitation and emission wavelengths do not overlap and signals are readily discriminated by the software. The fluorescence signal increases with the amount of formed amplicons.
Device Intended Use
The RIDA®GENE Norovirus GI/GII assay, performed on the Applied Biosystems® 7500 Fast Dx System, is a real-time RT-PCR in vitro diagnostic test for the qualitative detection and differentiation of norovirus genogroup I (GI) and II (GII) RNA from raw or unpreserved stool specimens collected from individuals with signs and symptoms of acute gastroenteritis.
The RIDA®GENE Norovirus GI/GII assay is intended for use as an aid in the differential diagnosis of norovirus genogroup I and II infections in patients symptomatic for gastroenteritis in conjunction with clinical evaluation, laboratory findings, and epidemiological information. The assay aids in the detection and identification of
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norovirus infections as the cause of acute gastroenteritis in sporadic cases as well as in the context of outbreaks.
Negative results do not preclude a norovirus infection and should not be used as the sole basis for diagnosis.
Substantial Equivalence
The RIDA GENE Norovirus GI/GII assay is substantially equivalent to the Xpert® Norovirus. Both are diagnostic tests for the simultaneous qualitative detection and differentiation of norovirus genogroup I and II nucleic acid in human stool specimens. There are no differences in the intended use population, sample material or technological principle of operation between the subject and the predicate device.
A multi-center clinical study was conducted to determine the performance characteristics of the RIDA®GENE Norovirus GI/GII assay. A composite comparator method that consisted of a combination of Center for Disease Control and Prevention (CDC) RT-PCR assays and bi-directional sequencing for norovirus has been used as the reference method. The Xpert® Norovirus used the same composite comparator method in a clinical study to determine its performance characteristics. The study results showed that the RIDA®GENE Norovirus GI/GII assay is acceptable for its intended use and is as safe and effective as the predicate device.
Table 1 shows a comparison of the RIDA®GENE Norovirus GI/GII assay to the predicate device Xpert® Norovirus.
| Similarities | ||
|---|---|---|
| Item | Device | Predicate |
| RIDA®GENE Norovirus GI/GII(K171511) | Xpert® Norovirus (K142501) | |
| Product code | PIQ, OOI | PIQ, OOI |
| Device class | II | II |
| Table 1 Comparison with predicate device | |||
|---|---|---|---|
| ------------------------------------------ | -- | -- | -- |
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| Intended use | The RIDA® GENE Norovirus GI/GIIassay, performed on the AppliedBiosystems® 7500 Fast Dx System, isa real-time RT-PCR in vitro diagnostictest for the qualitative detection anddifferentiation of norovirus genogroupI (GI) and II (GII) RNA from raw orunpreserved stool specimens collectedfrom individuals with signs andsymptoms of acute gastroenteritis.The RIDA®GENE Norovirus GI/GIIassay is intended for use as an aid inthe differential diagnosis of norovirusgenogroup I and II infections inpatients symptomatic forgastroenteritis in conjunction withclinical evaluation, laboratoryfindings, and epidemiologicalinformation. The assay aids in thedetection and identification ofnorovirus infections as the cause ofacute gastroenteritis in sporadic casesas well as in the context of outbreaks.Negative results do not preclude anorovirus infection and should not beused as the sole basis for diagnosis. | The Cepheid Xpert Norovirus Assay,performed on the GeneXpert® InstrumentSystems, is a qualitative in vitro diagnostictest for the identification anddifferentiation of norovirus genogroup Iand genogroup II RNA from raw orunpreserved unformed stool specimenscollected from individuals with symptomsof acute gastroenteritis. The test utilizesautomated real-time reverse transcriptasepolymerase chain reaction (RT-PCR) todetect norovirus RNA.The Cepheid Xpert Norovirus Assay isintended to aid in the diagnosis ofnorovirus infections when used inconjunction with clinical evaluation,laboratory findings, and epidemiologicalinformation. The assay also aids in thedetection and identification of norovirusinfectious in the context of outbreaks. |
|---|---|---|
| Specimen | Human stool | Same |
| Assay principle | Real-time reverse transcriptasepolymerase chain reaction (RT-PCR) | Same |
| Differences | ||
|---|---|---|
| Device | Predicate | |
| Item | RIDA®GENE Norovirus GI/GII(K171511) | Xpert® Norovirus (K142501) |
| AssayControl(s) | Bacteriophage MS2 as Internal ControlRNA (ICR) in each sample. Positivecontrol (PC) and negative controls(NC) processed with each batch ofsamples. | Sample processing control (SPC) andprobe check control (PCC) integratedin assay/instrument system. Externalcontrols available but not provided. |
| Extraction | bioMérieux NucliSENS® easyMAG®instrument | Self-contained and automated in theGeneXpert Cartridge and GeneXpertInstrument Systems. No reagentpreparation - all reagents are containedin the cartridge. |
| Analysis | Applied Biosystems®7500 FAST DxSystem | Cepheid GeneXpert Instrument Systems(GeneXpert Dx, GeneXpert Infinity-48and GeneXpert Infinity-80) |
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Analytical Performance:
Reproducibility
The reproducibility of the RIDA®GENE Norovirus GI/GII assay was evaluated at 3 laboratory sites. A panel of 5 samples with varying concentrations of Norovirus GI and Norovirus GII that included negative, moderate positive and low positive samples was tested in triplicates two times on each of five different days by two operators at each of the three sites (5 days x 2 times/day x 3 replicates x 3 sites). The same kit lot of RIDA GENE Norovirus GI/GII assay was used at each of the 3 testing sites. Table 2 summarizes the results calculated over all 3 study sites.
| Sample | Panel Member ID | Channel | n | Mean (Ct) | SD (Ct) | CV (%) |
|---|---|---|---|---|---|---|
| 1 | Negative | GI | 90 | 0.0 | 0.0 | n/a |
| 2 | Norovirus GI low positive | GI | 90 | 31.3 | 0.8 | 2.6 % |
| 3 | Norovirus GII low positive | GI | 90 | 0.0 | 0.0 | n/a |
| 4 | Norovirus GI moderate positive | GI | 90 | 27.9 | 0.9 | 3.1 % |
| 5 | Norovirus GII moderate positive | GI | 90 | 0.0 | 0.0 | n/a |
| 1 | Negative | GII | 90 | 0.0 | 0.0 | n/a |
| 2 | Norovirus GI low positive | GII | 90 | 0.0 | 0.0 | n/a |
| 3 | Norovirus GII low positive | GII | 90 | 30.7 | 0.8 | 2.5 % |
| 4 | Norovirus GI moderate positive | GII | 90 | 0.0 | 0.0 | n/a |
| 5 | Norovirus GII moderate positive | GII | 90 | 25.0 | 0.6 | 2.5 % |
Table 2 Reproducibility of the RIDA®GENE Norovirus GI/GII assay
SD: Standard deviation, CV: Coefficient of variation
n/a: For negative samples, no coefficient of variation is calculated,
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Precision
The precision of the RIDA®GENE Norovirus GI/GII assay was evaluated internally using a panel of 5 samples with varying concentrations of Norovirus GI and Norovirus GII that included negative, moderate positive and low positive samples. Experiments were performed in triplicates over 12 days with two runs per day by two operators at one study site (12 days, x 2 times/day x 3 replicates). Three independent kit lots were used for the precision study. The Inter-lot precision was calculated over those three kit lots. Results are shown in Table 3 and Table 4.
| Table 3 Intra-Site Precision of the KIDA GENE Norovirus GI/GII assay | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sample | Panel Member ID | Channel | n | Mean(Ct) | SD(Ct) | CV(%) | Mean(Ct) | SD(Ct) | CV(%) | Mean(Ct) | SD(Ct) | CV(%) |
| 1 | Negative | GI | 72 | 0.0 | 0.0 | n/a | 0.0 | 0.0 | n/a | 0.0 | 0.0 | n/a |
| 2 | Norovirus GI lowpositive | GI | 72 | 31.9 | 1.5 | 4.8 % | 32.0 | 1.4 | 4.4 % | 32.1 | 1.5 | 4.6 % |
| 3 | Norovirus GII lowpositive | GI | 72 | 0.0 | 0.0 | n/a | 0.0 | 0.0 | n/a | 0.0 | 0.0 | n/a |
| 4 | Norovirus GI moderatepositive | GI | 72 | 24.5* | 0.5 | 2.1 % | 24.8 | 0.5 | 1.9 % | 24.7 | 0.5 | 2.0 % |
| 5 | Norovirus GII moderatepositive | GI | 72 | 0.0 | 0.0 | n/a | 0.0 | 0.0 | n/a | 0.0 | 0.0 | n/a |
| 1 | Negative | GII | 72 | 0.0 | 0.0 | n/a | 0.0 | 0.0 | n/a | 0.0 | 0.0 | n/a |
| 2 | Norovirus GI lowpositive | GII | 72 | 0.0 | 0.0 | n/a | 0.0 | 0.0 | n/a | 0.0 | 0.0 | n/a |
| 3 | Norovirus GII lowpositive | GII | 72 | 31.0* | 1.9 | 6.1 % | 31.3 | 1.2 | 3.9 % | 31.3 | 0.9 | 2.8 % |
| 4 | Norovirus GI moderatepositive | GII | 72 | 0.0 | 0.0 | n/a | 0.0 | 0.0 | n/a | 0.0 | 0.0 | n/a |
| 5 | Norovirus GII moderatepositive | GII | 72 | 23.2 | 0.5 | 2.1 % | 23.3 | 0.6 | 2.4 % | 23.3 | 0.6 | 2.6 % |
Table 3 Intra-Site Precision of the RIDA GENE Norovirus GI/GIL assay
SD: Standard deviation, CV: Coefficient of variation
n/a: For negative samples no coefficient of variation is calculated.
*1 replicate is undetermined because of a pipetting error; replicate was retested.
| Table 4 Inter-Lot Precision of the RIDA GENE Norovirus GI/GII assay | |
|---|---|
| Sample | Panel Member ID | Channel | n | Inter-Lot | ||
|---|---|---|---|---|---|---|
| Mean (Ct) | SD (Ct) | CV (%) | ||||
| 1 | Negative | GI | 216 | 0.0 | 0.0 | n/a |
| 2 | Norovirus GI low positive | GI | 216 | 32.0 | 1.5 | 4.6 % |
| 3 | Norovirus GII low positive | GI | 216 | 0.0 | 0.0 | n/a |
| 4 | Norovirus GI moderate positive | GI | 216 | 24.7* | 0.5 | 2.0 % |
| 5 | Norovirus GII moderate positive | GI | 216 | 0.0 | 0.0 | n/a |
| 1 | Negative | GII | 216 | 0.0 | 0.0 | n/a |
| 2 | Norovirus GI low positive | GII | 216 | 0.0 | 0.0 | n/a |
| 3 | Norovirus GII low positive | GII | 216 | 31.2* | 1.4 | 4.5 % |
| 4 | Norovirus GI moderate positive | GII | 216 | 0.0 | 0.0 | n/a |
| 5 | Norovirus GII moderate positive | GII | 216 | 23.3 | 0.6 | 2.4 % |
SD: Standard deviation, CV: Coefficient of variation
n/a: For negative samples no coefficient of variation is calculated.
- 1 replicate is undetermined because of a pipetting error; replicate was retested.
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Analytical sensitivitv (Limit of Detection)
The limit of detection (LoD) was performed to evaluate the analytical sensitivity of RIDA®GENE Norovirus GI/GII using a dilution series of two native fecal samples, one genogroup I and one genogroup II into a negative stool matrix.
The genogroup of the two native samples was determined by conventional RT-PCR followed by bi-directional sequencing. Norovirus RNA copy numbers in the dilution series of fecal samples were determined by using two standard curves containing either GI or GII transcripts quantified by real-time RT-PCR. Measurements for the standard curve were performed in duplicate. LoD samples were tested by RIDA GENE Norovirus GI/GII applying the quantified standard curve described above.
The preliminary limit of detection of the RIDA "GENE Norovirus GI/GII was established based on the RNA copy number that gave a minimum of 2 out of 3 positive test results. The LoD was further verified by testing 20 replicates at the concentration determined in the preliminary studies. It was confirmed if all of those replicates yielded positive results. The RNA copy numbers per gram stool represent the mean values of the dilution series' triplicates for each dilution.
The Limits of Detection of the RIDA®GENE Norovirus GI/GII for the two genotypes are presented in Table 5.
| Limit of detection | |
|---|---|
| Norovirus GI (GI.3B) | 6.5x $10^5$ RNA copies/g stool |
| Norovirus GII (GII.4) | 2.5x $10^5$ RNA copies/g stool |
Table 5 Limit of detection of the RIDA®GENE Norovirus GI/GII assay
Cross reactivity
The analytical specificity of the RIDA®GENE Norovirus GI/GII assay was evaluated by testing a panel of 69 organisms, consisting of 56 bacteria, 1 fungus, 8 viruses, and 4 parasites representing common gastroenteritis pathogens or those potentially encountered in stool.
The analytical specificity study included testing of bacterial cultures at 10° to 10° cfu/ml, parasite and fungi cultures at 10' to 10' cfu/ml, and viral cell culture supernatants at 10' to 10° pfu/ml in the stool specimens.
The samples were extracted using the NucliSENS® easyMAG® System and tested on the Applied Biosystems 7500 Fast Dx platform. The analytical specificity of the RIDA®GENE Norovirus GI/GII assay was 100 %. Results are shown in Table 6.
| Organism | NorovirusGI | NorovirusGII | Organism | NorovirusGI | NorovirusGII |
|---|---|---|---|---|---|
| Acinetobacter Iwoffi | Negative | Negative | Helicobacter pylori | Negative | Negative |
| Adenovirus type 40 | Negative | Negative | Lactococcus lactis | Negative | Negative |
| Adenovirus type 41 | Negative | Negative | Listeria monocytogenes | Negative | Negative |
| Aeromonas caviae | Negative | Negative | Morganella morganii | Negative | Negative |
| Aeromonas hydrophila | Negative | Negative | Pleisomonas shigelloides | Negative | Negative |
| Astrovirus type 1 | Negative | Negative | Proteus mirabilis | Negative | Negative |
Table 6 Analytical Specificity of the RIDA®GENE Norovirus GI/GII assay
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| Astrovirus type 4 | Negative | Negative | Proteus vulgaris | Negative | Negative |
|---|---|---|---|---|---|
| Bacillus cereus | Negative | Negative | Providencia stuartii | Negative | Negative |
| Blastocystis hominis | Negative | Negative | Pseudomonas aeruginosa | Negative | Negative |
| Campylobacter coli | Negative | Negative | Pseudomonas fluorescens | Negative | Negative |
| Campylobacter jejuni | Negative | Negative | Pseudomonas putida | Negative | Negative |
| Candida albicans | Negative | Negative | Rotavirus G1 | Negative | Negative |
| Citrobacter freundii | Negative | Negative | Rotavirus G2 | Negative | Negative |
| Clostridium difficile | Negative | Negative | Rotavirus G3 | Negative | Negative |
| Clostridium sordellii | Negative | Negative | Rotavirus G4 | Negative | Negative |
| Cryptosporidium parvum | Negative | Negative | Rotavirus G9 | Negative | Negative |
| Entamoeba histolytica | Negative | Negative | Salmonella agona | Negative | Negative |
| Enterobacter cloacae | Negative | Negative | Salmonella bongori | Negative | Negative |
| Enterococcus faecalis | Negative | Negative | Salmonella enteritidis | Negative | Negative |
| Enterococcus faecium | Negative | Negative | Sapovirus GI.1 | Negative | Negative |
| Enterovirus | Negative | Negative | Sapovirus GIV | Negative | Negative |
| Escherichia coli (O157:H7;EHEC) | Negative | Negative | Sapovirus GV | Negative | Negative |
| Escherichia coli(0157; vtx1, vtx2, eae) | Negative | Negative | Serratia liquefaciens | Negative | Negative |
| Escherichia coli (O26:H-:EPEC) | Negative | Negative | Shigella flexneri | Negative | Negative |
| Escherichia coli (O26:H11;vtx2, eae) | Negative | Negative | Shigella sonnei | Negative | Negative |
| Escherichia coli (08; vtx1) | Negative | Negative | Staphylococcus aureus | Negative | Negative |
| Escherichia coli O103 | Negative | Negative | Steptococcus agalactiae | Negative | Negative |
| Escherichia coli O111 | Negative | Negative | Steptococcus dysgalactiae | Negative | Negative |
| Escherichia coli O121 | Negative | Negative | Vibrio cholerae | Negative | Negative |
| Escherichia coli O145 | Negative | Negative | Vibrio parahaemolyticus | Negative | Negative |
| Escherichia coli O45 | Negative | Negative | Viridans streptococci | Negative | Negative |
| Escherichia hermannii | Negative | Negative | Yersinia enterocolitica | Negative | Negative |
Analytical reactivity
The analytical reactivity of the RIDA®GENE Norovirus GI/GII assay was evaluated using twenty-four genotypes representing both norovirus genogroups (GI and GII). All strains evaluated in this study were tested at low (near LoD) and at high concentration. Each norovirus genotype was extracted using the NucliSENS® easyMAG® System and tested in triplicate on the Applied Biosystems® 7500 Fast Dx platform. As shown in Table 7, all norovirus genotypes were detected at both concentration levels by the RIDA®GENE Norovirus GI/GII assay.
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| Subgroup | NorovirusGI | NorovirusGII |
|---|---|---|
| GI.1 | Positive | Negative |
| GI.2 | Positive | Negative |
| GI.3 | Positive | Negative |
| GI.4 | Positive | Negative |
| GI.5 | Positive | Negative |
| GI.6 | Positive | Negative |
| GI.7 | Positive | Negative |
| GI.8 | Positive | Negative |
| Table 7 Analytical Reactivity of the RIDA "GENE Norovirus GI/GII assay | |||
|---|---|---|---|
| Subgroup | NorovirusGI | NorovirusGII |
|---|---|---|
| GII.1 | Negative | Positive |
| GII.2 | Negative | Positive |
| GII.3 | Negative | Positive |
| GII.4 Sydney | Negative | Positive |
| GII.4 New Orleans | Negative | Positive |
| GII.6 | Negative | Positive |
| GII.7 | Negative | Positive |
| GII.8 | Negative | Positive |
| GII.9 | Negative | Positive |
| GII.10 | Negative | Positive |
| GII.12 | Negative | Positive |
| GII.13 | Negative | Positive |
| GII.14 | Negative | Positive |
| GII.15 | Negative | Positive |
| GII.16 | Negative | Positive |
| GII.17 | Negative | Positive |
Interfering substances
To identify interfering substances that could affect the performance of the RIDA "GENE Norovirus GI/GII assay, an interference screen was performed. Therefore, potential interfering substances were added with appropriate concentrations (simulating either 1x or 3x the daily dose or "worst case" scenarios as appropriate) to 9 fecal samples containing the analyte (3 low positive GI. 3 low positive GII and 3 negative) For each sample, a common batch was prepared and subsequently aliquoted into 12 portions (11substances + 1 reference measurement). To each aliquot, one substance was added at the concentration stated in Table 5. To detect possible interference, the samples with and without added potential interfering substances were extracted in triplicates (each sample was extracted three times for every substance), tested and the results were compared to each other. There was no interference observed with the 11 potentially interfering substances tested (Table 8).
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| Substance | Concentration |
|---|---|
| Acetaminophen (analgesic) | 6.0 % (w/w) |
| Amoxicillin (antibiotic) | 4.5 % (w/w) |
| Aspartame (artificial sweetener) | 4.8 % (w/w) |
| Barium sulfate (radiocontrast agent) | 18.5 % (w/w) |
| Human blood (maybe found in patient stool) | 5.0 % (v/w) |
| Ibuprofen (analgesic) | 3.6 % (w/w) |
| Loperamide (anti-diarrhea drug) | 0.02 % (w/w) |
| Metronidazole (antibiotic) | 3.0 % (w/w) |
| Mucin (mucilage) | 5.0 % (w/w) |
| Pepto-Bismol (anti-diarrheal drug) | 6.3 % (v/w) |
| Stearic acid / Palmitic acid (1:1) (fatty acids) | 40.0 % (w/w) |
Table 8 Potentially interfering substances and tested final concentrations
Carry-over and Cross-contamination study
To evaluate the carry-over and cross-contamination with the RIDA®GENE Norovirus GI/GII assay in association with the NucliSENS® easyMAG® System and PCR on the Applied Biosystems® 7500 Fast Dx platform, an internal carry-over study was performed. In this study, one high positive GII sample (Ct value between 10 and 20) was measured 47 times alternating with a negative sample measured 47 times on the same plate. This setup was repeated for a total of 5 runs (negative adjacent positive). The data showed no carryover or cross contamination.
Clinical Performance
Performance characteristics of the RIDA®GENE Norovirus GI/GII assay were established during a prospective, multi-center study conducted at four institutions in the U.S. from February 2014 to April 2015. A total of 769 specimens were collected at the four different study sites. Of the 769 samples collected, 50 samples could not be used for study analysis.
In addition, 332 samples, prospectively collected during various previous outbreaks at two institutions, were tested from September 2016 to April 2017. Of the 332 samples, 300 samples provided valid results.
A total of 1019 study specimens consisted of raw or unpreserved stool specimens from subjects with symptoms of acute gastroenteritis. The RIDA GENE Norovirus GI/GII assay performance was compared to a composite reference method performed at the CDC (Atlanta, GA). Specifically, specimens were tested by conventional RT-PCR followed by bi-directional sequencing for both, Region C and Region D of norovirus.
The RIDA®GENE Norovirus GI/GII assay demonstrated 91.8 % PPA and 99.1 % NPA for detection of Norovirus GI, relative to the composite reference method (Table 9). The RIDA®GENE Norovirus GI/GII assay demonstrated 94.7 % PPA and 98.0 % NPA for detection of Norovirus GII (Table 0).
{13}------------------------------------------------
| Composite Reference Method | |||
|---|---|---|---|
| RIDA®GENE Norovirus GI/GII | Positive | Negative | Total |
| Positive | 56 | 9 | 65 |
| Negative | 5 | 949 | 954 |
| Total | 61 | 958 | 1019 |
| Positive Percent Agreement (95 % CI) | 91.8 % (56/61); (81.9 % – 97.3 %) | ||
| Negative Percent Agreement (95 % CI) | 99.1 % (949/958); (98.2% – 99.6 %) |
Table 9 Norovirus Genogroup I vs. Composite Reference Method
Table 10 Norovirus Genogroup II vs. Composite Reference Method
| Composite Reference Method | |||
|---|---|---|---|
| RIDA®GENE Norovirus GI/GII | Positive | Negative | Total |
| Positive | 213 | 16 | 229 |
| Negative | 12 | 778 | 790 |
| Total | 225 | 794 | 1019 |
| Positive Percent Agreement (95 % CI) | 94.7 % (213/225); (90.9 % – 97.2 %) | ||
| Negative Percent Agreement (95 % CI) | 98.0 % (778/794); (96.7 % – 98.8 %) |
Conclusion
The results of the nonclinical analytical and clinical performance studies summarized above demonstrate that the RIDA®GENE Norovirus GI/GII is substantially equivalent to the predicate device.
§ 866.3990 Gastrointestinal microorganism multiplex nucleic acid-based assay.
(a)
Identification. A gastrointestinal microorganism multiplex nucleic acid-based assay is a qualitativein vitro diagnostic device intended to simultaneously detect and identify multiple gastrointestinal microbial nucleic acids extracted from human stool specimens. The device detects specific nucleic acid sequences for organism identification as well as for determining the presence of toxin genes. The detection and identification of a specific gastrointestinal microbial nucleic acid from individuals exhibiting signs and symptoms of gastrointestinal infection aids in the diagnosis of gastrointestinal infection when used in conjunction with clinical evaluation and other laboratory findings. A gastrointestinal microorganism multiplex nucleic acid-based assay also aids in the detection and identification of acute gastroenteritis in the context of outbreaks.(b)
Classification. Class II (special controls). The special controls are set forth in FDA's guideline document entitled: “Class II Special Controls Guideline: Gastrointestinal Microorganism Multiplex Nucleic Acid-Based Assays for Detection and Identification of Microorganisms and Toxin Genes from Human Stool Specimens.” For availability of the guideline document, see § 866.1(e).