(144 days)
The 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 human whole blood collected in sodium citrate from individuals suspected of having anthrax, positive blood cultures, and 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, 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) Device Anthrax Detection System is a fully integrated in-vitro diagnostic (IVD) system composed of the JBAIDS instrument with laptop computer, software, 2 different freeze-dried reagent assays (in one kit) for the qualitative detection of pathogenic Bacillus anthracis, and 3 different sample preparation protocols for isolating target DNA from whole blood, blood culture, or direct culture.
The JBAIDS instrument, using Polymerase Chain Reaction (PCR) technology, is a portable thermocycler and real-time fluorimeter. The JBAIDS Anthrax Detection Kit is specially designed for PCR in glass capillaries using the JBAIDS instrument and hydrolysis probes for detection of the pXO1 plasmid (Target 1) and the pXO2 plasmid (Target 2) DNA sequences. A fragment of plasmid DNA is amplified using specific primers, creating amplicon. The amplicon is detected using a specific hydrolysis probe, which is a short oligonucleotide that hybridizes to an internal sequence of the amplified fragment during the annealing phase of the PCR cycle. This probe has the 5' and 3' ends labeled with a reporter dye and a quenching dye, respectively. When the probe hybridizes to the specific DNA target, the Taq polymerase enzyme replicating the target-specific DNA hydrolyzes the probe, separating the two fluorophores, thus allowing the reporter dye to fluoresce.
The reagent kit contains 4 different types of freeze-dried reagent vials: Positive Controls, Negative Controls, Inhibition Controls, and Unknowns (used for testing the patient sample). Each JBAIDS run requires a Positive and Negative Control, and each sample is tested using both an Inhibition Control vial and an Unknown reagent vial. The characteristics of the amplification curves from the positive control (PC), negative control (NC), inhibition controls (IC) and from each unknown sample are analyzed by the JBAIDS Software, and results are reported as Positive. Negative, Inhibited or Uncertain. When PCs or NCs are unacceptable, the test results for all samples in the JBAIDS run are considered invalid and must be repeated.
Prior to testing, whole-blood samples are purified using the Idaho Technology IT 1-2-37M FLOW Sample Purification Kit (or validated equivalent), while blood culture and direct culture specimens are prepared using the IT 1-2-31M SWIPE Sample Purification Kit (or validated equivalent). The resulting purified sample is added to an Unknown reagent vial and an Inhibition Control reagent vial, along with reconstitution buffer.
Here's an analysis of the acceptance criteria and the study that proves the device meets them, based on the provided text:
JBAIDS Anthrax Detection System Acceptance Criteria and Study Details
1. Table of Acceptance Criteria and Reported Device Performance
The provided document does not explicitly state formal "acceptance criteria" with numerical thresholds for sensitivity and specificity in a table format for the JBAIDS Anthrax Detection System. Instead, it describes performance characteristics that demonstrate substantial equivalence to a predicate device and good analytical and clinical performance. The closest interpretation of acceptance criteria would be that the device needs to achieve high sensitivity and specificity in detecting B. anthracis targets, similar to or exceeding the predicate method.
Here's a summary of the stated performance:
| Performance Metric | Acceptance Criteria (Implied / Stated Goal) | Reported Device Performance (JBAIDS Anthrax Detection System) |
|---|---|---|
| Analytical Sensitivity: | Detect B. anthracis targets (pXO1 & pXO2) in virulent strains |
- Direct Culture Panel: 23/23 (100%) detected
- Blood Culture Panel: 11/11 (100%) detected
- Whole Blood Spiked Samples: 67/68 (98.5%) detected (at limit of detection levels) |
| Analytical Specificity: | No cross-reactivity with non-B. anthracis organisms | - Direct Culture Panel: 34/37 (91.9%) negative for non-B. anthracis strains
- Blood Culture Panel: 12/12 (100%) negative for non-B. anthracis strains
- Note: Cross-reacted with 3 virulent B. cereus strains known to cause anthrax-like illness. |
| Clinical Specificity: | No false positives in samples from individuals suspected of anthrax (but without confirmed anthrax) | 150/150 (100%) negative in blood samples from hospitalized subjects (95% CI, 98%-100%) |
| Equivalence to Predicate (CDC Gamma Phage Lysis Assay): | As effective as predicate, with additional benefits | "As effective as the predicate assay," "easier to use," "highly sensitive and specific." |
2. Sample Sizes and Data Provenance
The provided document indicates the following sample sizes and data provenance:
-
Test Set (Analytical Studies):
- Direct Culture Panel: 23 virulent B. anthracis strains (positive detection) + 37 non-B. anthracis strains (negative detection) = 60 samples.
- Blood Culture Panel: 11 virulent B. anthracis strains (positive detection) + 12 non-B. anthracis strains (negative detection) = 23 samples.
- Whole Blood Spiked Samples: 68 samples spiked with limit of detection levels of live B. anthracis.
- Data Provenance: The document does not explicitly state the country of origin. It refers to "virulent strains of B. anthracis tested" and "non-B. anthracis strains." Given the context of CDC involvement and FDA submission, it's highly likely these were laboratory-controlled samples and reference strains, possibly from a national or international repository, and not necessarily patient data from a specific country. This appears to be retrospective testing of characterized samples.
-
Test Set (Clinical Specificity Study):
- Sample Size: 150 blood samples.
- Data Provenance: "Blood samples from hospitalized subjects with clinical signs and symptoms consistent with inhalation or systemic anthrax and for whom a blood culture had been ordered." This indicates a prospective data collection from a clinical setting, presumably within the US. The document does not specify the exact location(s).
3. Number of Experts and Qualifications for Ground Truth
The document does not explicitly state the number of experts used or their specific qualifications (e.g., "radiologist with 10 years of experience") for establishing ground truth in a systematic way for the test set.
However, for the predicate device and confirmation methods:
- Predicate Method: The predicate for the JBAIDS Anthrax Detection Kit is "traditional microbiological identification of the organism (preamendment methods) with confirmation by the Centers for Disease Control Laboratory Response Network Gamma Phage Lysis assay." This implies that the ground truth for B. anthracis identification was established by microbiologists and experts within the CDC's Laboratory Response Network, following standard microbiological identification criteria and the gamma phage lysis assay procedure.
- Confirmation for Analytical Studies: For the direct culture and blood culture panels, "all of the samples were confirmed as B. anthracis using standard biochemical identification and tested positive using the CDC Reference Laboratory Procedure for Identification of B. anthracis Using Lysis by Gamma Phage." This again points to verification by microbiology experts using established CDC protocols.
4. Adjudication Method for the Test Set
The document does not describe an explicit adjudication method (e.g., 2+1, 3+1). The ground truth for the analytical studies was established by standard biochemical identification and the CDC Reference Laboratory Procedure for Identification of B. anthracis Using Lysis by Gamma Phage, which are definitive laboratory methods rather than subjective expert consensus requiring adjudication.
For the clinical specificity study, the ground truth for ruling out anthrax was "not identified in any of the blood cultures." This implies a definitive laboratory result rather than a consensus decision requiring adjudication.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. The JBAIDS Anthrax Detection System is an in-vitro diagnostic (IVD) PCR system that provides an automated result (Positive, Negative, Inhibited, Uncertain). It's an algorithm-only device without a human-in-the-loop component in its primary function, thus improvements in human reader performance with or without AI assistance are not applicable.
6. Standalone (Algorithm Only) Performance
Yes, a standalone (algorithm only) performance study was done for the JBAIDS Anthrax Detection System. The device itself is an automated system that uses PCR technology to detect specific DNA sequences and its software then analyzes the amplification curves and reports results as Positive, Negative, Inhibited, or Uncertain (as described in the "Description" section).
The performance metrics reported (sensitivity, specificity, detection rates for various samples) are directly from the JBAIDS system's automated output.
7. Type of Ground Truth Used
The ground truth used was:
- Microbiological Identification/Pathology: For the analytical studies, ground truth for B. anthracis presence was established by "standard biochemical identification and ... the CDC Reference Laboratory Procedure for Identification of B. anthracis Using Lysis by Gamma Phage." For non-B. anthracis strains, their identification as non-anthrax was also based on standard microbiological characterization.
- Outcomes Data (Indirect/Surrogate): For the clinical specificity study, the ground truth for the absence of anthrax was based on "blood cultures" being negative for B. anthracis. This serves as a clinical outcome surrogate to confirm the absence of the infection in symptomatic patients.
8. Sample Size for the Training Set
The document does not specify the sample size for a training set. This is common for PCR-based IVD systems, where the "training" (development and optimization) often relies on well-characterized laboratory strains and known genetic sequences rather than a distinct "training set" in the machine learning sense. The device is designed to detect known specific DNA sequences rather than learn patterns from a broad dataset.
9. How Ground Truth for the Training Set Was Established
As no specific "training set" is mentioned, the method for establishing ground truth for training data is not provided. However, the development of the assays (e.g., designing primers and probes for pXO1 and pXO2) would rely on the established genomic sequences of B. anthracis, confirmed by techniques such as genomic sequencing, traditional microbiological identification, and confirmed virulence studies from expert laboratories like the CDC. The document highlights that the targets (pXO1 and pXO2 plasmids) are "essential for the organism's pathogenicity," implicitly referencing well-established biological facts about B. anthracis.
§ 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.