(53 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 enterococci and staphylococci. After inoculation, panels are incubated for 4.5 - 18 hours at 35°C +/- 1°C, in a WalkAway® SZ, or equivalent, and read by the MicroScan® Instrumentation. Additionally, the panels may be incubated in a non-CO2incubator 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 nitrofurantoin, at concentrations of 2 to 256 ug/ml, for enterococci and staphylococci, to the test panel.
The gram-positive organisms which may be used for nitrofurantoin susceptibility testing in this panel are:
Enterococcus species Staphylococcus aureus
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 enterococci and staphylococci.
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, or equivalent, System, 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.
1. Acceptance Criteria and Reported Device Performance
| Performance Metric | Acceptance Criteria (from "Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA", dated February 5, 2003) | Reported Device Performance (MicroScan® Synergies plus™ Gram-Positive MIC/Combo Panels with nitrofurantoin) |
|---|---|---|
| Overall Essential Agreement | Not explicitly stated in the provided text, but implied as a benchmark for "acceptable performance" compared to a reference method. | 98.8% |
| Reproducibility and Precision | Acceptable reproducibility and precision | Demonstrated acceptable reproducibility and precision |
| Quality Control Testing | Acceptable results | Demonstrated acceptable results |
2. Sample Size Used for the Test Set and Data Provenance
The provided text does not explicitly state the exact sample size used for the test set. It mentions "external validation was conducted with fresh and stock Efficacy isolates and stock Challenge strains." However, the specific number of isolates is not quantifiable from the given information.
The data provenance is from an external validation study. The location of this study (e.g., country of origin) is not specified. The study appears to be retrospective in that it uses "stock Efficacy isolates and stock Challenge strains," suggesting they were collected prior to the study.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The document does not mention the use of experts to establish ground truth for the test set. Instead, the performance of the device was compared against a "frozen Reference Panel" and "Expected Results determined prior to the evaluation" for challenge strains. This suggests an objective, standardized reference method was used rather than expert consensus.
4. Adjudication Method for the Test Set
Not applicable. The ground truth was established by comparison to a "frozen Reference Panel" and "Expected Results," not through human adjudication.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No. The provided text describes a study evaluating the performance of an automated antimicrobial susceptibility testing system against a reference method. It does not involve human readers evaluating cases or comparing human performance with and without AI assistance.
6. Standalone (i.e., algorithm only without human-in-the-loop performance) Performance
Yes, this was a standalone performance study. The MicroScan® Synergies plus™ Gram-Positive MIC/Combo Panels system is an automated device designed to determine antimicrobial susceptibility. The study evaluated the performance of this automated system directly (algorithm only) against a reference method.
7. Type of Ground Truth Used
The ground truth was established by comparison to a "frozen Reference Panel" and "Expected Results" for challenge strains. This implies a standardized, objective, and predefined reference for antimicrobial susceptibility.
8. Sample Size for the Training Set
The document does not provide any information regarding a training set or its sample size. The focus is on the validation of the device's performance against a reference.
9. How the Ground Truth for the Training Set Was Established
Not applicable, as no training set information is provided.
§ 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.”