(62 days)
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°C +/- 1°C, 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 AST portions can be read visually, according to the Package Insert.
This particular submission is for the addition of the antimicrobial agent Trimethoprim/Sulfamethoxazole, at concentrations of 0.5/9.5 to 8/152 ug/ml, to the test panel.
The gram-positive organisms which may be used for Trimethoprim/Sulfamethoxazole susceptibility testing in this panel are:
Staphylococcus aureus
Staphylococcus epidermidis
Staphylococcus species - Coagulase Negative
Staphylococcus saprophyticus
MicroScan® Synergies plus™ Gram-Positive MIC/Combo Panels, utilizing both the MicroScan® Rapid Fluorogenic Identification and Dried Overnight Antimicrobial Susceptbility Testing (AST) technologies, are designed for use in determining quantitative 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" Pos Broth, after inoculation with a standardized suspension of the organism. After incubation in the WalkAway® SI 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 provided text regarding the acceptance criteria and study for the MicroScan® Synergies plus™ Gram-Positive MIC/Combo Panels with Trimethoprim/Sulfamethoxazole:
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria | Reported Device Performance (Trimethoprim/Sulfamethoxazole) |
|---|---|
| Overall Essential Agreement with frozen Reference panel | >98% |
| Instrument Reproducibility | Acceptable |
| Quality Control | Acceptable |
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size: Not explicitly stated as a numerical value. The document mentions "fresh and stock Efficacy isolates and stock Challenge strains" were used for external evaluation. It does not provide the total number of isolates or challenge strains.
- Data Provenance: Retrospective, as indicated by the use of "stock Efficacy isolates and stock Challenge strains." The country of origin is not specified but implicitly within the US given the FDA submission.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
- Number of Experts: Not explicitly stated.
- Qualifications of Experts: Not specified. The ground truth (Expected Results) for Challenge strains was "determined prior to the evaluation," implying expert consensus or established references.
4. Adjudication Method for the Test Set
- Adjudication Method: Not explicitly stated. The comparison is made against a "CLSI frozen Reference Panel" for the main evaluation and "Expected Results" for challenge strains. This suggests a direct comparison against established standards rather than an adjudication process between multiple readers of the device's results.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done
- MRMC Study: No, an MRMC comparative effectiveness study was not done. This type of study is more relevant for diagnostic imaging or subjective interpretation devices. For a highly automated system like an AST panel, the comparison is typically against a reference method rather than human readers.
6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) was done
- Standalone Performance: Yes, the study evaluates the performance of the MicroScan® Synergies plus™ Gram-Positive MIC/Combo Panel itself without human interpretation as the primary outcome. The device automatically determines the Minimum Inhibitory Concentration (MIC) for the test organism, and this is then compared to a reference method. While human interaction is involved in setting up the test and reading results, the "performance" described (Essential Agreement, Reproducibility, QC) refers to the device's output.
7. The Type of Ground Truth Used
- Ground Truth Type:
- External Evaluation: "CLSI frozen Reference Panel" for performance comparison, which represents a recognized gold standard for antimicrobial susceptibility testing.
- Challenge Strains: "Expected Results" which were "determined prior to the evaluation," likely based on expert consensus, established reference methods, or known characteristics of the challenge strains.
8. The Sample Size for the Training Set
- Sample Size: Not applicable/not provided. This device is not described as using a machine learning algorithm that requires a "training set" in the traditional sense. It's a chemical and instrumentation-based system that follows established protocols.
9. How the Ground Truth for the Training Set Was Established
- Ground Truth Establishment: Not applicable as there is no "training set" for this type of device. The system relies on precise dilutions, reagent reactions, and growth inhibition principles, rather than learning from data.
§ 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.”