(25 days)
To determine bacterial antimicrobial agent susceptibility
The MicroScan MICroSTREP plus® Panel is used to determine quantitative and/or qualitative antimicrobial agent susceptibility of colonies grown on solid media of aerobic streptococci, including Streptococcus pneumoniae. After inoculation, panels are incubated for 20 - 24 hours at 35°C +/- 1°C in a non-CO2 incubator, and read visually according to the Package Insert. Additionally, the panels may be incubated in and read by a MicroScan® WalkAway instrument.
This particular submission is for the addition of instrument read capability of the antimicrobial Vancomycin, at concentrations of 0.06 to 8 mcg/ml on the MicroScan MICroSTREP plus® Panel.
The organisms which may be used for Vancomycin susceptibility testing in this panel are:
Streptococcus pneumoniae (including penicillin-resistant strains) Streptococcus pyogenes Streptococcus agalactiae the viridans group Streptococcus bovis
The MicroScan MICroSTREP plus® Panel is used to determine quantitative and/or qualitative antimicrobial agent susceptibility of colonies grown on solid media of aerobic streptococci, including Streptococcus pneumoniae. After inoculation, panels are incubated for 20 - 24 hours at 35°C +/-1 °C in a non-CO2 incubator, and read according to the Package Insert.
The antimicrobial susceptibility tests are miniaturizations of the broth dilution susceptibility test. 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 115 ul Mueller-Hinton broth supplemented with 2-5% lysed horse blood (LHB) and buffered with 50 mM HEPES, after inoculation of the broth with a standardized suspension of the organism in saline. After incubation in a non-CO2 incubator for 20-24 hours, the minimum inhibitory concentration (MIC) for the test organism is manually read by observing the lowest antimicrobial concentration showing inhibition of growth. Additionally, the panels may be incubated in and read by a MicroScan WalkAway instrument.
Acceptance Criteria and Device Performance Study for MicroScan MICroSTREP plus® Panel (Vancomycin)
This document describes the acceptance criteria and the study proving the device meets these criteria for the MicroScan MICroSTREP plus® Panel when used to determine bacterial susceptibility to Vancomycin with instrument reading capabilities.
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria | Reported Device Performance |
|---|---|
| Essential Agreement (between instrument read results and Expected Results) | 100% for Vancomycin |
| Reproducibility | Acceptable reproducibility and precision for Vancomycin and WalkAway® instrument |
| Quality Control | Acceptable results for Vancomycin |
2. Sample Size Used for the Test Set and Data Provenance
The external evaluation was conducted with stock and CDC Challenge strains. The exact number of strains/isolates used in the test set is not explicitly stated in the provided text.
The data provenance is retrospective, as the external evaluations were designed to compare the proposed instrument read method with "Expected Results determined before the evaluation." This implies that the reference results (Expected Results) were established prior to the instrument reading. The origin of the stock and CDC Challenge strains is not specified in terms of country.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
The document does not explicitly state the number of experts used to establish the ground truth (Expected Results) or their specific qualifications. It only refers to "Expected Results determined before the evaluation."
4. Adjudication Method for the Test Set
The document does not specify an adjudication method (e.g., 2+1, 3+1). It states that the instrument read results were compared with "Expected Results," implying a pre-established reference.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
There is no indication that a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was done to assess how much human readers improve with AI vs. without AI assistance. The focus of this submission is on the instrument-read performance of the AST panel, not on human interpretation or AI assistance.
6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study
Yes, a standalone study was conducted. The evaluation primarily focused on the instrument's performance ("instrument read method") when compared to a pre-defined ground truth ("Expected Result"). The document emphasizes "instrument read results" and "instrument reproducibility testing," indicating that the device's performance as a standalone automated reader was assessed.
7. Type of Ground Truth Used
The type of ground truth used was reference panel results. The document states that the instrument's performance was compared with an "expected result generated on a CLSI frozen Reference Panel, as defined in the FDA document 'Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA', dated February 5, 2003."
8. Sample Size for the Training Set
The document does not provide information regarding a distinct "training set" or its sample size. The evaluation described focuses on an external validation set (test set) against a defined ground truth.
9. How the Ground Truth for the Training Set Was Established
As there is no explicit mention of a training set, the method for establishing its ground truth is not detailed. The ground truth for the test set was established using a "CLSI frozen Reference Panel."
§ 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).