(219 days)
The MicroScan Dried Gram-Positive MIC/Combo Panel is used to determine quantitative and qualitative antimicrobial agent susceptibility of colonies grown on solid media of rapidly growing aerobic and facultative gram-positive cocci, some fastidious aerobic gram-positive cocci and Listeria monocytogenes. After inoculation, panels are incubated for 16-20 hours at 35°C ± 1°C in a non-CO2 incubator, and read either visually or with MicroScan instrumentation, according to the Package Insert.
This particular submission is for the addition of the antimicrobial daptomycin at concentrations of 0.06-32 µg/mL to the test panel. Testing is indicated for Enterococcus faecium, Enterococcus spp. other than E. faecium, and Staphylococcus spp., as recognized by the FDA Susceptibility Test Interpretive Criteria (STIC) webpage.
The MicroScan Dried Gram-Positive MIC/Combo Panels with Daptomycin (DAP) (0.06-32 µg/mL) has demonstrated acceptable performance with the following organisms:
- Enterococcus faecium
- Enterococcus spp. other than E. faecium (Enterococcus faecalis, Enterococcus avium, Enterococcus raffinosus, Enterococcus casseliflavus and Enterococcus durans)
- Staphylococcus spp. (Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus capitis, Staphylococcus haemolyticus, Staphylococcus lugdunensis, Staphylococcus hominis, Staphylococcus warneri, Staphylococcus simulans, Staphylococcus saprophyticus, Staphylococcus intermedius, and Staphylococcus sciuri)
MicroScan Dried Gram-Positive MIC/Combo Panels 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 bacteria.
The principle of MicroScan panels with antimicrobial susceptibility tests are miniaturizations of the broth dilution susceptibility test that have been diluted in broth and dehydrated. Various antimicrobial agents are diluted in broth to concentrations bridging the range of clinical interest. Panels are rehydrated with water after inoculation with a standardized suspension of the organism. After incubation in a non-CO2 incubator for 16-20 hours, the minimum inhibitory concentration (MIC) for the test organism is read by determining the lowest antimicrobial concentration showing inhibition of growth.
This product is single-use and intended for laboratory professional use.
The provided text specifies the performance validation of the MicroScan Dried Gram-Positive MIC/Combo Panels with Daptomycin (DAP). Here's a breakdown of the acceptance criteria and study information:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria are implicitly defined by the reported performance metrics against a CLSI (Clinical and Laboratory Standards Institute) frozen Reference Panel. The primary metrics are Essential Agreement (EA) and Categorical Agreement (CA).
| Organism Group | Performance Metric | Acceptance Criteria (Implicit) | Reported Device Performance |
|---|---|---|---|
| Staphylococcus spp. | Essential Agreement (EA) | Acceptable performance | 94.3% |
| Categorical Agreement (CA) | Acceptable performance | 99.5% | |
| Enterococcus faecium | Essential Agreement (EA) | Acceptable performance | 90.8% |
| Categorical Agreement (CA) | Acceptable performance | 92.0% | |
| Enterococcus species other than E. faecium | Essential Agreement (EA) | Acceptable performance | 100.0% |
| Categorical Agreement (CA) | Acceptable performance | 94.1% |
Note: The document states "acceptable performance" without defining specific numerical thresholds for EA and CA as explicit "acceptance criteria." However, the reported values are presented as meeting this "acceptable performance." In antimicrobial susceptibility testing, typical FDA guidance for acceptable EA is generally $\geq$90% and for CA is general $\geq$90% to 95%, depending on the organism/drug combination and resistance rates.
2. Sample Size Used for the Test Set and Data Provenance
The document mentions "external evaluations" conducted with:
- Fresh and stock Efficacy isolates
- Stock Challenge strains
It does not explicitly state the numerical sample size (number of isolates/strains) used for the test set.
The data provenance is not explicitly stated regarding country of origin or whether it was retrospective or prospective. Given the mention of "external evaluations," it implies that the testing was performed, but the location and study design (retrospective/prospective) are not detailed. Standard AST studies typically involve prospective collection of clinical isolates and/or the use of well-characterized reference strains.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
The ground truth for the test set was established by comparison with a CLSI frozen Reference Panel. This implies that the reference standard, and thus the "ground truth," is determined by a highly standardized and validated laboratory method (broth microdilution or similar CLSI-recognized standard).
The document does not mention human experts being used directly to establish the ground truth for individual cases in the test set. Instead, the CLSI frozen Reference Panel itself serves as the gold standard.
4. Adjudication Method for the Test Set
No human adjudication method (e.g., 2+1, 3+1) is mentioned or implied, as the ground truth is established by the CLSI frozen Reference Panel, not by human interpretation or consensus.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done
This is not applicable to this device. This device is an Antimicrobial Susceptibility Test (AST) panel, which determines the Minimum Inhibitory Concentration (MIC) of an antimicrobial agent against bacteria. It does not involve human readers interpreting images, and therefore, an MRMC study is not relevant. The device measures a quantitative result (MIC) which is then interpreted categorically (susceptible, intermediate, resistant) based on established breakpoints.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was done
Yes, this study represents a standalone performance evaluation of the device. The "MicroScan Dried Gram-Positive MIC/Combo Panels with Daptomycin" is a diagnostic test system. Its performance is evaluated against a recognized reference method (CLSI frozen Reference Panel) to determine its accuracy in reporting MIC values and categorical interpretations. While human operators inoculate and read the panels (either visually or with MicroScan instrumentation), the "performance" being assessed here is the device's ability to produce accurate results compared to the reference standard, not an AI algorithm's ability to interpret data without human input.
7. The type of Ground Truth Used
The ground truth used was comparison to a CLSI frozen Reference Panel. This is a laboratory-based gold standard for antimicrobial susceptibility testing, representing the accepted accurate measurement of MIC. It is a highly controlled and standardized method.
8. The Sample Size for the Training Set
The document does not mention a "training set" in the context of machine learning or AI. This is an AST panel, not an AI/ML diagnostic algorithm that requires a training set. The performance validation is based on a comparison to a reference standard using a test set of bacterial isolates/strains.
9. How the Ground Truth for the Training Set Was Established
As there is no concept of a training set for this type of device (AST panel based on traditional microbiological principles), this question is not applicable.
§ 866.1640 Antimicrobial susceptibility test powder.
(a)
Identification. An antimicrobial susceptibility test powder is a device that consists of an antimicrobial drug powder packaged in vials in specified amounts and intended for use in clinical laboratories for determining in vitro susceptibility of bacterial pathogens to these therapeutic agents. Test results are used to determine the antimicrobial agent of choice in the treatment of bacterial diseases.(b)
Classification. Class II (performance standards).