(39 days)
The Joint Biological Agent Identification and Diagnostic System (JBAIDS) Anthrax Detection System is a real-time polymerase chain reaction (PCR) test system intended for the qualitative in vitro diagnostic (IVD) detection of target DNA sequences on the pXO1 plasmid (Target 1) and the pXO2 plasmid (Target 2) from Bacillus anthracis. The system can be used to test the following:
- Human whole blood collected in sodium citrate from individuals suspected of having anthrax
- Positive blood cultures
- Cultured organisms grown on blood agar plates.
The JBAIDS Anthrax Target 2 assay is used as a supplementary test only after a positive result with the Target 1 Assay.
The JBAIDS Anthrax Target 1 and Target 2 Assays are run on the JBAIDS instrument using the Diagnostic Wizard. Results are for the presumptive identification of B. anthracis, in conjunction with culture and other laboratory tests. The following considerations also apply: - The diagnosis of anthrax infection must be made based on history, signs, symptoms, exposure likelihood, and other laboratory evidence, in addition to the identification of pXO1 and pXO2 targets either from cultures or from direct blood specimens.
- The assays have not been evaluated with blood from individuals without clinical signs or symptoms who were presumed exposed and who subsequently developed anthrax (inhalation or other forms of the disease), or from individuals with any form of anthrax (inhalational, cutaneous, or gastrointestinal).
- The level of plasmid targets that would be present in blood from individuals with early systemic infection is unknown.
- The definitive identification of B. anthracis from colony growth, liquid blood culture growth, or from blood specimens requires additional testing and confirmation procedures in consultation with public health or other authorities for whom reports are required.
The safety and effectiveness of other types of tests or sample types (not identified as "For in vitro diagnostic use") have not been established.
The Joint Biological Agent Identification and Diagnostic System (JBAIDS) Anthrax Detection System is a fully integrated IVD system composed of the portable JBAIDS instrument, laptop computer and software, the JBAIDS Anthrax Detection Kit with two different freeze-dried PCR assays for detection of pathogenic Bacillus anthracis DNA. The system has been validated using four different sample preparation kits for isolating DNA from whole blood (IT 1-2-3TM Platinum Path, QFLOWdma, FLOW Sample Purification Kits), positive blood cultures (IT I-2-3TM SWIPE Sample Purification Kit), and plate cultures (IT 1-2-3™ Platinum Path and SWIPE Sample Purification Kits). Use of the JBAIDS DNA Extraction Control Kit is also recommended.
Prior to testing, specimens are processed using BioFire Diagnostic's IT 1-2-3 Sample Purification Kits. The resulting purified sample is added to Target 1 Unknown and Target 1 Inhibition Control vials, along with reconstitution buffer. Target 1 Positive Control and Negative Control vials are prepared using reconstitution buffer and water. When B. anthracis DNA is present, a fragment of B. anthracis DNA is amplified. The amplicon is detected by fluorescence using a specific hydrolysis probe. Each probe is labeled on one end with a fluorescent reporter moiety (6-carboxyfluorescein (6-FAM)) and elsewhere with a quencher moiety (carboxy tetramethylrhodamine (TAMRA)). When the probe is intact, the quencher absorbs the light emitted by the reporter moiety. During PCR, the probe hybridizes to the target sequence before the exonuclease activity of Taq polymerase hydrolyzes the probe, separating the fluorophore from the quencher and permitting detection of the fluorescent signal generated by the reporter. The fluorescent signal increases as additional templates are amplified and more probes are hydrolyzed.
JBAIDS Software analyzes the fluorescence amplification curves and reports results as positive, negative, uncertain or inhibited. A failure of the Positive or Negative Control will result in the entire run being called invalid. Retesting is required to resolve uncertain, invalid or inhibited results. The Target 2 assay is used as a supplementary test only after a positive result is obtained with the Target 1 assay.
Here's a breakdown of the acceptance criteria and study information based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
The submission primarily focuses on demonstrating equivalence of a new DNA extraction method (Platinum Path) to an existing one (QFLOWdna) for use with the JBAIDS Anthrax Detection Kit. Therefore, the "acceptance criteria" are implicitly defined by the performance of the predicate device with the QFLOWdna kit, and the "reported device performance" is how the new Platinum Path kit compares.
| Performance Metric | Acceptance Criteria (Implicit from Predicate/QFLOWdna) | Reported Device Performance (with Platinum Path) |
|---|---|---|
| Clinical Performance (Surrogate Whole Blood) | ||
| Positive Percent Agreement (PPA) | Equivalent to QFLOWdna (presumably near 100% for positive samples) | 100% (50/50; 95% CI = 92.9-100%) |
| Negative Percent Agreement (NPA) | Equivalent to QFLOWdna (presumably near 100% for negative samples) | 100% (50/50; 95% CI = 92.9-100%) |
| Limit of Detection (LoD) | Previously established LoD of 1000 CFU/mL in whole blood (for Target 1 and Target 2) | 1000 CFU/mL (20/20 detected for both targets) |
| Reproducibility | Consistent performance across sites for medium positive, low positive, and negative samples | 100% agreement with expected results for all sites and spike levels, for both Target 1 and Target 2 |
| Direct Culture Samples (B. anthracis) | 100% detection of B. anthracis colonies | 10/10 B. anthracis colonies detected |
| Direct Culture Samples (Non-B. anthracis) | 0% detection of non-B. anthracis colonies | 0/10 non-B. anthracis colonies detected |
2. Sample Size Used for the Test Set and Data Provenance
-
Clinical Performance (Surrogate Whole Blood):
- Sample Size: 100 surrogate whole blood specimens (50 spiked with B. anthracis, 50 not spiked). Each sample was processed by both new (Platinum Path) and old (QFLOWdna) extraction methods and then tested.
- Data Provenance: Prospectively collected from febrile volunteers in the USA (November 2012 to April 2013). These were surrogate specimens spiked with inactivated B. anthracis, not true clinical anthrax samples.
-
Limit of Detection:
- Sample Size: 20 independent whole blood specimens, each spiked with B. anthracis at the LoD level.
- Data Provenance: Not explicitly stated, but implied to be laboratory-prepared samples for analytical validation.
-
Reproducibility:
- Sample Size: A panel of 12 blood samples (4 medium positive, 4 low positive, 4 negative). Each sample was tested twice a day for four days at each of three testing sites. Total individual tests for each target would be 12 samples * 2 tests/day * 4 days * 3 sites = 288 for each target (Target 1 and Target 2).
- Data Provenance: Multicenter study, locations are "Site 1, Site 2, Site 3." Country of origin not explicitly stated, but typically assumed to be domestic for FDA submissions unless otherwise specified.
-
Detection of Direct Culture Samples:
- Sample Size: 10 B. anthracis colonies and 10 non-B. anthracis colonies.
- Data Provenance: Not explicitly stated, but implied to be laboratory-prepared cultures.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications
The ground truth for the surrogate clinical specimens and analytical studies was established by:
- Spiking Status: Knowing which samples were spiked with inactivated B. anthracis and at what concentration, and which were not. This is a controlled laboratory process, not dependent on human expert interpretation for definitive classification.
- Predicate Device Performance: For the surrogate clinical specimens, the "correct result" was defined by the JBAIDS result when processed with the QFLOWdna kit, which is the predicate/established method. This avoids the need for external expert consensus on the B. anthracis status of a sample that has already been spiked.
Therefore, no external clinical experts were used to establish the ground truth in the traditional sense for these studies. The ground truth was based on the controlled spiking of samples and comparison to an established method.
4. Adjudication Method for the Test Set
Not applicable in the traditional sense. The "ground truth" for the surrogate clinical specimens was determined by the results from the predicate extraction method (QFLOWdna), and for the analytical studies, it was determined by the known spiking status of the samples. There was no need for expert adjudication of conflicting results as the comparison was against a predetermined "truth."
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done
No, an MRMC comparative effectiveness study was not done. This device is a molecular diagnostic test for B. anthracis DNA, not an imaging device that would typically involve human readers interpreting images. The study focuses on the analytical and clinical (surrogate) performance of the extraction method and PCR kit.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
Yes, the studies presented are standalone (algorithm only). The JBAIDS system, with its software, analyzes the fluorescence amplification curves and reports results (positive, negative, uncertain, inhibited). The operators were blinded to the analyte content, meaning their human "interpretation" was limited to running the instrument and following its automated output. The performance metrics (PPA, NPA, LoD, reproducibility) are based directly on the device's output.
7. The Type of Ground Truth Used
- Clinical Performance (Surrogate Whole Blood): Known spiking status of the samples from a laboratory perspective, and the performance of the predicate DNA extraction method (QFLOWdna) as the "correct result" for comparison.
- Limit of Detection: Known concentration of spiked B. anthracis in laboratory-prepared whole blood specimens.
- Reproducibility: Known concentration of spiked B. anthracis (medium, low, or unspiked).
- Detection of Direct Culture Samples: Known identity of the bacterial colonies (either B. anthracis or non-B. anthracis) through laboratory culture and identification.
8. The Sample Size for the Training Set
The document does not explicitly mention a "training set" for the device itself. This submission is for modifications to an existing device (the JBAIDS Anthrax Detection Kit) by adding compatibility with a new sample purification kit (IT 1-2-3 Platinum Path). The JBAIDS system and its algorithm were presumably developed and validated previously. The studies described here are a validation of the new sample preparation method, not the training of a new algorithm.
9. How the Ground Truth for the Training Set Was Established
Since there is no explicit mention of a "training set" for a new algorithm within this submission, this question is not directly applicable. The JBAIDS Anthrax Detection System already existed and was previously cleared (K051713 and K071188). The ground truth for its initial development and validation would have followed similar principles of known positive and negative samples, likely through spiking and confirmed cultures, as is typical for molecular diagnostic assays.
§ 866.3045 In vitro diagnostic device for
Bacillus spp. detection.(a)
Identification. An in vitro diagnostic device forBacillus species (spp.) detection is a prescription device used to detect and differentiate amongBacillus spp. and presumptively identifyB. anthracis and otherBacillus spp. from cultured isolates or clinical specimens as an aid in the diagnosis of anthrax and other diseases caused byBacillus spp. This device may consist ofBacillus spp. antisera conjugated with a fluorescent dye (immunofluorescent reagents) used to presumptively identify bacillus-like organisms in clinical specimens; bacteriophage used for differentiatingB. anthracis from otherBacillus spp. based on susceptibility to lysis by the phage; or antigens used to identify antibodies toB. anthracis (anti-toxin and anti-capsular) in serum. Bacillus infections include anthrax (cutaneous, inhalational, or gastrointestinal) caused byB. anthracis, and gastrointestinal disease and non-gastrointestinal infections caused byB. cereus. (b)
Classification. Class II (special controls). The special controls are set forth in FDA's special controls guideline document entitled “In Vitro Diagnostic Devices forBacillus spp. Detection; Class II Special Controls Guideline for Industry and Food and Drug Administration Staff.” For availability of the guideline document, see § 866.1(e).(c)
Restriction on Distribution. The distribution of these devices is limited to laboratories that follow public health guidelines that address appropriate biosafety conditions, interpretation of test results, and coordination of findings with public health authorities.(d)
Restriction on Use. The use of this device is restricted to prescription use and must comply with the following:(1) The device must be in the possession of:
(i)(A) A person, or his agents or employees, regularly and lawfully engaged in the manufacture, transportation, storage, or wholesale or retail distribution of such device; or
(B) A practitioner, such as a physician, licensed by law to use or order the use of such device; and
(ii) The device must be sold only to or on the prescription or other order of such practitioner for use in the course of his professional practice.
(2) The label of the device shall bear the statement “Caution: Federal law restricts this device to sale by or on the order of a ____”, the blank to be filled with the word “physician” or with the descriptive designation of any other practitioner licensed by the law of the State in which he practices to use or order the use of the device.
(3) Any labeling, as defined in section 201(m) of the Federal Food, Drug, and Cosmetic Act, whether or not it is on or within a package from which the device is to be dispensed, distributed by, or on behalf of the manufacturer, packer, or distributor of the device, that furnishes or purports to furnish information for use of the device contains adequate information for such use, including indications, effects, routes, methods, and frequency and duration of administration and any relevant hazards, contraindications, side effects, and precautions, under which practitioners licensed by law to employ the device can use the device safely and for the purposes for which it is intended, including all purposes for which it is advertised or represented. This information will not be required on so-called reminder-piece labeling which calls attention to the name of the device but does not include indications or other use information.
(4) All labeling, except labels and cartons, bearing information for use of the device also bears the date of the issuance or the date of the latest revision of such labeling.