(22 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 Clindamycin, at concentrations of 0.015 to 2 mcg/ml on the MicroScan MICroSTREP plus® Panel and the removal of the "Do not report" for S. pneumoniae.
The organisms which may be used for Clindamycin susceptibility testing on this panel are:
Streptococci Streptococcus pneumoniae
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.
The provided text describes a 510(k) premarket notification for a medical device called the MicroScan MICroSTREP plus® Panel, specifically focusing on its ability to determine bacterial susceptibility to Clindamycin. The submission aims to add instrument-read capability for Clindamycin and remove a "Do not report" limitation for Streptococcus pneumoniae.
Here's an analysis of the acceptance criteria and the study that proves the device meets them:
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria Category | Specific Criteria | Reported Device Performance |
|---|---|---|
| Essential Agreement (EA) | Overall EA ≥ 95.7% for Clindamycin compared with the Expected Result, including S. pneumoniae. | Achieved: "The MICroSTREP plus® Panel demonstrated acceptable performance with an overall Essential Agreement of ≥95.7% for Clindamycin compared with the Expected Result including S. pneumoniae." |
| Instrument Reproducibility | Acceptable reproducibility and precision with Clindamycin and the WalkAway® instrument. | Achieved: "Instrument reproducibility testing demonstrated acceptable reproducibility and precision with Clindamycin and the WalkAway® instrument." |
| Quality Control (QC) | Acceptable results for Clindamycin. | Achieved: "Quality Control testing demonstrated acceptable results for Clindamycin." |
| Substantial Equivalence | Demonstrated substantially equivalent performance with streptococcal isolates when compared with an expected result generated on a CLSI frozen Reference Panel, as defined in FDA guidance document. | Achieved: "The proposed instrument read method for the MicroScan MICroSTREP plus® Panel demonstrated substantially equivalent performance with streptococcal isolates when 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." |
2. Sample Size Used for the Test Set and Data Provenance
The document does not explicitly state the exact sample size for the external evaluations, but it mentions a test set consisting of:
- CDC Challenge strains: Used to confirm the acceptability of the instrument read method.
- Fresh and stock isolates: Used from the original external design validation of the manual method to support removing the "Do not report" limitation for S. pneumoniae.
The data provenance is not explicitly stated in terms of country of origin. The study appears to be retrospective in a sense that it uses "fresh and stock isolates" from a previous validation, but also likely includes prospective data for the specific instrument-read capability evaluation. Given the context of FDA submission, the data likely originates from studies conducted or overseen in the United States.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The document does not specify the number or qualifications of experts used to establish the ground truth. It refers to an "Expected Result generated on a CLSI frozen Reference Panel" and "Expected Results determined before the evaluation." This implies that the ground truth was established by recognized reference methods and possibly validated expert consensus according to CLSI guidelines, but the specific individuals are not mentioned.
4. Adjudication Method for the Test Set
The document does not explicitly state an adjudication method (e.g., 2+1, 3+1). The comparison is made against an "Expected Result," which implies a pre-established ground truth rather than a process of adjudicating discrepancies among multiple expert readers for the purpose of the study.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. The study's focus is on comparing the device's performance (instrument-read method vs. expected reference result) rather than evaluating how human readers' performance changes with or without AI assistance. This is a standalone device validation, not a human-in-the-loop clinical efficacy study in that specific MRMC sense.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
Yes, a standalone study was done. The entire evaluation focuses on the MicroScan® WalkAway instrument's ability (the "algorithm/instrument only") to read the MICroSTREP plus® Panel accurately for Clindamycin. The phrase "proposed instrument read method" and the comparison to an "Expected Result" highlights this standalone performance assessment. While the panels can be "read manually," the study specifically validates the instrument-read capability.
7. The Type of Ground Truth Used
The ground truth used is primarily based on an "Expected Result generated on a CLSI frozen Reference Panel" and "Expected Results determined before the evaluation." This implies a highly standardized and validated laboratory reference method, likely aligned with Clinical and Laboratory Standards Institute (CLSI) guidelines, which is considered a gold standard for antimicrobial susceptibility testing.
8. The Sample Size for the Training Set
The document does not explicitly state the sample size for a "training set." This type of device (an AST panel read by an instrument) is typically validated against reference methods for its performance rather than trained like a machine learning algorithm. The "CDC Challenge strains" and "fresh and stock isolates" serve as the test data for validation, not a training set in the machine learning sense.
9. How the Ground Truth for the Training Set Was Established
As there is no explicit mention of a 'training set' in the context of a machine learning model, the question of establishing its ground truth is not directly applicable. The "Expected Result" from the CLSI frozen Reference Panel and other pre-determined expected results serve as the benchmark for evaluation, not as ground truth for training an algorithm in a supervised learning paradigm. The instrument's reading mechanism is likely based on optical detection and pre-programmed algorithms designed to interpret growth patterns, rather than being "trained" on a large dataset in the modern AI sense.
§ 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).