(20 days)
MicroScan® Synergies plus™ Gram-Negative MIC/Combo Panel is used to determine quantitative and/or qualitative antimicrobial agent susceptibility of colonies grown on sold media of rapidly growing aerobic and facultative anaerobic Gram-Negative bacilli (Enterobacteriaceae, glucose non-fermenters, and non-Enterobacteriaceae glucose fermenters. After inoculation, panels are read on the WalkAway® SI System or equivalent (upgraded WalkAway® 40 or WalkAway® 96) according to the Package Insert. This particular submission is for the antimicrobial Tobramycin on the Synergies plus™ Gram-Negative MIC/Combo Panels.
MicroScan® rapID/S plus™ Gram-Negative 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-negative bacilli. The MicroScan® rapID/S plus™ Gram-Negative MIC/Combo Panels are read on the WalkAway® SI System or equivalent (upgraded WalkAway® 40 or WalkAway® 96 instruments). The antimicrobial susceptibility tests are miniaturizations of the broth dilution susceptibility test that have been diluted in Mueller-Hinton Broth to concentrations bridging the range of clinical interest and are presented in micro-titer wells in dried form. rapID/S plus™ panels are inoculated and rehydrated with a standardized suspension of the organism and incubated at 35℃ in the WalkAway® SY System or equivalent for 4.5 - 18 hours. The minimum inhibitory concentration (MIC) for the test organism is determined by the lowest antimicrobial concentration showing inhibition of growth.
The provided text describes the MicroScan® Synergies Plus Gram-Negative MIC/Combo Panels with Tobramycin, a device used for antimicrobial agent susceptibility testing. The original submission was for the MicroScan® rapID/S plus™ Gram-Negative MIC/Combo panel, and the name was later changed.
Here's an analysis of the acceptance criteria and the study that proves the device meets those criteria:
1. Table of Acceptance Criteria and Reported Device Performance
| Performance Metric | Acceptance Criteria (or equivalent) | Reported Device Performance (Tobramycin) |
|---|---|---|
| Essential Agreement | Not explicitly stated as a numerical criterion in the provided text, but implied as "acceptable performance" as defined in the FDA DRAFT document "Guidance on Review Criteria for Assessment of Antimicrobial Susceptibility Devices". | 96.6% (when compared with the NCCLS frozen Reference panel) |
| Reproducibility | "acceptable reproducibility and precision" | Demonstrated acceptable reproducibility and precision. |
| Quality Control | "acceptable results" | Demonstrated acceptable results. |
2. Sample Size Used for the Test Set and Data Provenance
The text states that the external evaluation was conducted with fresh and stock Efficacy isolates and stock Challenge strains. However, the exact sample size (number of isolates/strains) used for the test set is not explicitly provided in the given document.
The data provenance is described as an "external evaluation." While the country of origin isn't specified, the reference to "FDA DRAFT document 'Guidance on Review Criteria for Assessment of Antimicrobial Susceptibility Devices'" suggests a U.S. regulatory context. Given the nature of susceptibility testing, it would typically be prospective, as the device is being tested against these isolates to determine its performance.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications
The document does not specify the number of experts used or their qualifications to establish the ground truth for the test set.
4. Adjudication Method for the Test Set
The document does not describe an adjudication method for the test set. The comparison was primarily against an "NCCLS frozen Reference Panel" and "Expected Results" for challenge strains, which suggests a direct comparison method rather than expert adjudication of discrepancies.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done
No, an MRMC comparative effectiveness study was not done. This type of study would typically involve human readers interpreting results with and without AI assistance to quantify performance improvement. This device (MicroScan® Synergies Plus) is an automated system for determining antimicrobial susceptibility, not an AI-assisted diagnostic tool that aids human interpretation in the same way an imaging AI might. Therefore, the concept of "improving human readers with AI vs without AI assistance" does not directly apply here.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
Yes, the study described is a standalone performance study. The MicroScan® Synergies Plus system, read on the WalkAway® SI System, is designed to provide results without human interpretation of the raw susceptibility data beyond loading the panel and retrieving the processed results. The stated "Essential Agreement of 96.6% for Tobramycin when compared with the frozen Reference panel" reflects the algorithm's performance in determining MIC values.
7. The Type of Ground Truth Used
The ground truth for the test set was established using:
- NCCLS frozen Reference Panel: This is a standardized method for antimicrobial susceptibility testing, considered the gold standard for comparison in many such studies.
- Expected Results: For "Challenge strains," their susceptibility profiles were pre-determined and used as the "Expected Results" for comparison. This implies either expert consensus, prior laboratory reference methods, or established databases for known challenge strains.
8. The Sample Size for the Training Set
The document does not provide information about a separate "training set" or its sample size. This type of device's development typically involves establishing methodologies and validating them against known standards rather than training a machine learning model on a distinct dataset in the way a modern AI algorithm might be.
9. How the Ground Truth for the Training Set Was Established
Since a dedicated "training set" is not mentioned, the method for establishing its ground truth is not applicable/provided in this document. The development of the MicroScan® system would have relied on established microbiological principles and validated reference methods.
§ 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.”