(54 days)
To determine antimicrobial agent susceptibility
The MicroScan® Synergies plus™ Gram-Positive MIC/Combo Panel is used to determine quantitative and/or qualitative antimicrobial agent susceptibility of colonies grown on solid media of rapidly growing aerobic and facultative anaerobic gram-positive staphylococci and enterococci. After inoculation, panels are incubated for 4.5 - 18 hours at 35℃ +/- 1℃, in a WalkAway® SI, or equivalent, and read by the MicroScan® Instrumentation. Additionally, the panels may be incubated in a non-CO2 incubator and the Antimicrobial Susceptibility Testing (AST) portions can be read visually, according to the Package Insert.
This particular submission is for the addition of the antimicrobial Rifampin, at concentrations of 0.25 to 8 ug/ml, to the test panel.
The gram-positive organisms which may be used for Rifampin susceptibility testing in this panel are:
Staphylococcus aureus (including methicillin-resistant strains/MRSA) Staphylococcus epidermidis
MicroScan® Synergies plus™ Gram-Positive MIC/Combo Panels, utilizing both the MicroScan® Rapid Fluorogenic Identification and Dried Overnight Antimicrobial Susceptibility Testing (AST) technologies, are designed for use in determining quantitative and/or qualitative antimicrobial agent susceptibility of colonies grown on solid media of rapidly growing aerobic and facultative anaerobic gram-positive staphylococci and enterococci.
The antimicrobial susceptibility tests are miniaturizations of the broth dilution susceptibility test that have been diluted in water and dehydrated. Various antimicrobial agents are diluted in water, buffer, or minute concentrations of broth, to concentrations bridging the range of clinical interest. Panels are rehydrated with Synergies plus™ Post Broth, after inoculation with a standardized suspension of the organism. After incubation in the WalkAway® SZ System, or equivalent, for 4.5 - 18 hours, the minimum inhibitory concentration (MIC) for the test organism is read by determining the lowest antimicrobial concentration showing inhibition of growth.
Here's an analysis of the acceptance criteria and study details from the provided 510(k) summary (K051478):
Acceptance Criteria and Device Performance
The core acceptance criterion for the MicroScan® Synergies plus™ Gram-Positive MIC/Combo Panels with Rifampin, as stated, is based on a comparison to a frozen Reference Panel.
Context: The FDA document "Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA", dated February 5, 2003, defines the performance standards for such devices. While the exact numerical acceptance criteria for each metric (Essential Agreement, Category Agreement, etc.) are not explicitly detailed in the provided text, the summary indicates that the device met these criteria.
| Acceptance Criteria Category | Reported Device Performance | Comments |
|---|---|---|
| Essential Agreement (EA) | >98% for Rifampin | Performance against a frozen Reference Panel. Essential Agreement is a measure of how closely the MIC results (within ±1 dilution) compare between the test device and the reference method. |
| Reproducibility | Acceptable | Confirmed for both filled panels and inoculum preparation methods, using the WalkAway® SI System or equivalent. |
| Precision | Acceptable | Similar to reproducibility, ensures consistent results under repeated testing. |
| Quality Control (QC) | Acceptable results | For Rifampin. Ensures the system performs as expected with known controls. |
Study Details
The provided text describes an "external evaluation" that served as the primary study to demonstrate substantial equivalence.
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A table of acceptance criteria and the reported device performance:
(See table above) -
Sample size used for the test set and the data provenance:
- Sample Size: Not explicitly stated as a number of isolates. The summary mentions "fresh and stock Efficacy isolates and stock Challenge strains" were used for the external evaluation. Without a specific count, the exact sample size cannot be determined from this text.
- Data Provenance: The origin of the isolates (e.g., country of origin, specific hospitals) is not specified. It refers to "external evaluation," implying the testing was conducted outside of the manufacturer's primary lab, but the specific location is not given. The isolates are categorized as retrospective given they are "stock Efficacy isolates" and "stock Challenge strains," and "fresh isolates" which suggests some prospective collection, but no further details are provided on the "fresh" isolates.
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Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience):
- Not applicable/Not explicitly stated. For AST devices, the "ground truth" or reference method is typically another well-established AST method (e.g., broth microdilution) rather than human expert interpretation of an image or clinical observation. The study compared the device's results to a "frozen Reference Panel," which implicitly serves as the ground truth. There is no mention of human experts directly establishing ground truth for individual cases.
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Adjudication method (e.g. 2+1, 3+1, none) for the test set:
- Not applicable. Adjudication methods like 2+1 or 3+1 are typically used in studies where human readers interpret complex data (e.g., medical images) and need to reach consensus. For AST, the comparison is directly between the result from the test device and the result from the reference method. Discrepancies are analyzed, but not subjected to a human adjudication process in the same way.
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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:
- Not applicable. This device is an automated in vitro diagnostic antimicrobial susceptibility test system, not an AI-assisted diagnostic tool that directly aids human readers in interpreting complex data. Therefore, an MRMC study comparing human reader performance with and without AI assistance is not relevant to this device.
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If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:
- Yes, effectively. The performance described (Essential Agreement >98%) is the standalone performance of the MicroScan® Synergies plus™ Gram-Positive MIC/Combo Panel system compared to the reference method. While human involvement is required for initial panel inoculation and system operation, the MIC determination and interpretation of that result are automated by the "MicroScan® Instrumentation" (WalkAway® SZ System or equivalent). The exception is that AST portions can be read visually, but the primary claims for the automated system would be based on its automated readings.
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The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
- Reference Method/Frozen Reference Panel: The ground truth was established by a "frozen Reference Panel." This likely refers to a panel tested using a recognized reference method for antimicrobial susceptibility testing, such as a broth microdilution or agar dilution method, which is considered the gold standard for MIC determination. The "Expected Results determined prior to the evaluation" for Challenge strains also fall under this category.
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The sample size for the training set:
- The document does not explicitly mention a separate "training set" or its sample size. For traditional AST devices, the development process generally involves extensive internal testing and refinement (which could be considered analogous to training) using a wide array of isolates, but this is distinct from the formal "external evaluation" or validation study. The 510(k) summary focuses on the validation study that demonstrates the device's performance against a reference.
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How the ground truth for the training set was established:
- As no specific training set is mentioned in the provided text, the method for establishing its ground truth is also not detailed. In the context of AST device development, internal testing would generally involve comparison to a recognized reference method, similar to the validation study.
§ 866.1645 Fully automated short-term incubation cycle antimicrobial susceptibility system.
(a)
Identification. A fully automated short-term incubation cycle antimicrobial susceptibility system is a device that incorporates concentrations of antimicrobial agents into a system for the purpose of determining in vitro susceptibility of bacterial pathogens isolated from clinical specimens. Test results obtained from short-term (less than 16 hours) incubation are used to determine the antimicrobial agent of choice to treat bacterial diseases.(b)
Classification. Class II (special controls). The special control for this device is FDA's guidance document entitled “Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA.”