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The Gamma Phage assay is a lytic phage assay specific for Bacillus anthracis. The Gamma Phage assay (common name) can be used on suspect non-hemolytic, aerobic, gram-positive, "ground-glass"- appearing colonies from sheep blood agar in conjunction with other markers and testing for the identification of Bacillus anthracis. The assay is not intended for screening of blood or plasma donors.

Use of this assay is limited to designated laboratory Response Network (LRN) and Department of Defense (D0D).

The gamma phage is a lytic bacteriophage which binds to specific cell-surface components of susceptible bacteria. Their DNA is injected into the bacterium. The gamma phage replicate within the bacterium and produce PlyG lysine (2), resulting in lysis of the infected cell and release of phage. The release of newly synthesized phage leads to another round of phage infection and lysis.

Materials Supplied:

• Bacillus anthracis Gamma Phage Suspension, 0.5 ml
• . Positive Control, Bacillus anthracis Pasteur Strain Spore Suspension, 1.0 ml
• Negative Control, Bacillus cereus Spore Suspension, 1.0 ml ●

Materials required but not supplied:

• . 5% Sheep Blood Agar plate
• . Inoculating loops, 1ul and 10 ul
• Aerosol resistant pipette tips
• . Disinfectant

Equipment required:

• Pipettor, 5-50 µ1
• Incubator, 35+/- 2 °C
• Biological Safety Cabinet, Class II
• Refrigerator, 2-8 ℃ .

Here's a summary of the acceptance criteria and study information for the Gamma Phage Lysis Assay for the Identification of Bacillus anthracis, based on the provided document:

The document describes a Special 510(k) submission (K143592) for the Gamma Phage Lysis assay, which is specific for Bacillus anthracis. The submission states that the only modification made to the previously cleared predicate device (K051794) is a change in the positive control strain from Bacillus anthracis Pasteur strain to Bacillus anthracis Sterne strain. The document claims this change does not impact assay performance.

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly state quantitative acceptance criteria (e.g., specific sensitivity/specificity thresholds) or provide detailed performance metrics (like sensitivity, specificity, accuracy) for the K143592 device itself. Instead, it relies on the substantial equivalence argument, asserting that the performance characteristics are identical to the predicate device because the only change (positive control strain) does not impact assay performance.

Therefore, the "acceptance criteria" can be inferred as maintaining the performance of the predicate device for identifying Bacillus anthracis.

2. Sample Size Used for the Test Set and Data Provenance

The document does not describe a new clinical or laboratory study with a "test set" to establish the performance of the K143592 device independently. The basis for substantial equivalence is that the only change (positive control strain) does not alter the fundamental performance of the assay. Therefore, there is no specific test set sample size or provenance information for K143592 provided in this document as it pertains to proving the performance of the assay itself. The performance relies on the previous clearance of K051794 and the argument that the modification is minor.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

Not applicable, as no new independent test set study is described for K143592 to establish ground truth for performance. The performance is considered equivalent to the predicate.

4. Adjudication Method for the Test Set

Not applicable, as no new independent test set study is described.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, and the Effect Size of How Much Human Readers Improve with AI vs. Without AI Assistance

Not applicable. This device is a rapid diagnostic assay for bacterial identification, not an AI-assisted diagnostic tool or an imaging device requiring human reader interpretation in the context of an MRMC study.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done

The device is a laboratory assay. Its performance is inherent to the reagents and protocol. The document does not provide details of an internal "standalone" study for K143592, as its performance is considered unchanged from the predicate device. The assay itself operates "standalone" in the sense that it provides a direct result without human "interpretation" of complex data (like images), but rather observation of lysis.

7. The Type of Ground Truth Used

For the predicate device (K051794) and by extension for K143592, the ground truth for Bacillus anthracis identification would typically be established through:

• Culture and biochemical identification: Standard microbiological methods to identify bacterial species.
• Molecular methods: Such as PCR, targeting specific B. anthracis genes.
• Referral laboratory confirmation: Confirmation by a qualified reference laboratory using a suite of confirmatory tests.

The document implicitly relies on these established methods for identifying Bacillus anthracis to validate the specificity and lytic activity of the gamma phage. The positive and negative controls provided with the kit (e.g., Bacillus anthracis Sterne strain and Bacillus cereus spore suspension) serve as internal ground truth checks for each run of the assay.

8. The Sample Size for the Training Set

Not applicable. This is a traditional diagnostic assay, not a machine learning or AI model that requires a "training set."

9. How the Ground Truth for the Training Set Was Established

Not applicable, as there is no training set for this type of device.

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