(31 days)
To determine antimicrobial agent susceptibility
MicroScan Dried 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 antimicrobial susceptibility tests are miniaturizations of the broth dilution susceptibility test that have been diluted in broth and dehydrated. Various antimicrobial agents are diluted in broth to concentrations bridging the range of clinical interest. Panels are rehydrated with water after inoculation with a standardized suspension of the organism. After incubation in a non-CO2 incubator for 16-20 hours, the minimum inhibitory concentration (MIC) for the test organism is read by determining the lowest antimicrobial concentration showing inhibition of growth.
This document describes a Special 510(k) submission for a medical device called the MicroScan Dried Gram-Negative MIC/Combo Panels with Meropenem, specifically for an additional indication for use with Acinetobacter spp. The information provided allows us to extract the acceptance criteria and study details.
Here's the breakdown of the acceptance criteria and the study proving the device meets them:
1. Table of Acceptance Criteria and the Reported Device Performance
| Criterion | Acceptance Criteria (Target) | Reported Device Performance (Acinetobacter spp. with Meropenem) |
|---|---|---|
| Essential Agreement (EA) | Not explicitly stated, but typically ≥ 90% for AST systems | 91.1% |
| Categorical Agreement (CA) | Not explicitly stated, but typically ≥ 90% for AST systems | 98.2% |
| Inoculum and Instrument Reproducibility | "Acceptable reproducibility and precision" | Demonstrated acceptable reproducibility and precision. |
| Quality Control | "Acceptable results" | Demonstrated acceptable results. |
Note: While specific percentage thresholds for EA and CA acceptance are not explicitly stated in the provided text, for Antimicrobial Susceptibility Test (AST) systems, FDA guidance typically expects Essential Agreement and Categorical Agreement to be at least 90% for new indications.
2. Sample Size Used for the Test Set and Data Provenance
The document mentions "combined efficacy and challenge data" and "external evaluations" conducted with "fresh and stock Efficacy and Challenge isolates." However, the specific sample size (number of isolates/strains) used for the test set is NOT explicitly provided in the text.
The provenance of the data is not specified in terms of country of origin. The study appears to be prospective as it involves "external evaluations" and testing with "fresh and stock" isolates and comparison to a CLSI frozen Reference panel, implying new data generation for this submission.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
The document states that the device performance was compared "with a CLSI frozen Reference Panel." A CLSI (Clinical and Laboratory Standards Institute) reference panel implies a well-established and validated method for determining antimicrobial susceptibility, which serves as the gold standard.
The document does NOT explicitly state the number of experts or their qualifications involved in establishing the ground truth using the CLSI frozen Reference Panel. The CLSI method itself is the 'expert' in this context, representing a consensus-driven standard.
4. Adjudication Method for the Test Set
The document does not describe an "adjudication method" in the sense of multiple human readers independently assessing results and then resolving discrepancies. Instead, the study's design involves:
- Comparing the MicroScan Dried Gram-Negative MIC/Combo Panels with a CLSI frozen Reference panel. This reference panel serves as the definitive gold standard.
- The agreement metrics (Essential Agreement and Categorical Agreement) are calculated by comparing the results from the device to the results from the CLSI reference panel.
Therefore, an explicit human adjudication process is not applicable or described for this type of test, as the ground truth is established by a standardized laboratory method (CLSI).
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 (MRMC) is typically relevant for interpretative diagnostic devices where human readers evaluate images or data, and AI assists or replaces them. This submission is for an in-vitro diagnostic (IVD) device that determines antimicrobial susceptibility, not for image interpretation or diagnosis by human readers in the classical sense of an MRMC study.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
Yes, the primary performance evaluation appears to be a standalone (algorithm only) assessment. The "MicroScan Dried Gram-Negative MIC/Combo Panels" and associated instruments (WalkAway instrument) determine the MIC, which is then directly compared to the CLSI reference panel. While human operators are involved in setting up the test and reading the final MIC (which is then used to determine susceptibility), the comparison metrics (EA and CA) directly assess the output of the device relative to the reference method, not the human interpretation of that output.
7. The Type of Ground Truth Used
The type of ground truth used is a CLSI frozen Reference Panel. This represents a highly standardized and validated laboratory method for determining antimicrobial susceptibility, considered the gold standard for AST devices.
8. The Sample Size for the Training Set
The document does NOT specify the sample size for the training set. This submission is a Special 510(k) for an additional indication for an existing device. It focuses on the performance data for the specific indication requested (Acinetobacter spp. with Meropenem). Information regarding the original training set for the broader device development is not provided.
9. How the Ground Truth for the Training Set Was Established
Since the training set sample size is not provided, how its ground truth was established is also not described in this document. For AST devices, the ground truth for training (if an AI/ML component were heavily involved in the core susceptibility determination, which doesn't appear to be the case here as it's an assay system) would typically also be established using CLSI reference methods or other well-accepted laboratory standards for bacterial identification and susceptibility.
§ 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).