(62 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.
This particular submission is for the addition of the antimicrobial Ceftriaxone at concentrations of 0.015 to 8 mcg/ml to the test panel
The organisms which may be used for Ceftriaxone susceptibility testing in this panel are:
Streptococcus pneumoniae
Streptococcus pyogenes
viridans group streptococci
The MicroScan® MICroSTREP plus™ 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.
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% bysed 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.
The MicroScan® MICroSTREP plus™ Panel is intended to determine bacterial susceptibility to Ceftriaxone. The study aimed to demonstrate substantial equivalence to an NCCLS frozen Reference Panel.
1. Acceptance Criteria and Reported Device Performance
| Acceptance Criteria | Reported Device Performance |
|---|---|
| Overall Essential Agreement with NCCLS frozen Reference panel | 97.5% for Ceftriaxone |
| Reproducibility | Acceptable |
| Quality Control | Acceptable |
Essential Agreement (EA): This typically means that the MIC result of the device is within one doubling dilution of the reference method's MIC result. The FDA DRAFT document "Guidance on Review Criteria for Assessment of Antimicrobial Susceptibility Devices", dated March 8, 2000, defines the specific criteria for acceptable performance. The 97.5% Essential Agreement indicates that the device's results are very close to the reference standard for Ceftriaxone.
2. Sample Size and Data Provenance
- Test Set Sample Size: The document mentions "external evaluation was conducted with fresh and stock Efficacy isolates and stock Challenge strains". However, the exact number of isolates/strains used in the test set is not explicitly stated.
- Data Provenance: The study was an "external evaluation," meaning it was likely conducted independently from the device manufacturer to ensure impartiality. The data provenance is not specified by country, but it adheres to FDA guidelines, implying a US regulatory context for the study design and evaluation. The data included both fresh isolates (prospective collection) and stock isolates/strains (likely retrospective or historical collections).
3. Number of Experts and Qualifications for Ground Truth
The document does not explicitly state the number of experts used or their detailed qualifications for establishing the ground truth. However, the ground truth was established by comparing the device's performance against an "NCCLS frozen Reference Panel." The NCCLS (National Committee for Clinical Laboratory Standards, now Clinical and Laboratory Standards Institute - CLSI) sets recognized standards for antimicrobial susceptibility testing. The processes for maintaining and evaluating these reference panels would involve highly qualified microbiologists and laboratory professionals.
4. Adjudication Method
The document does not explicitly mention an adjudication method for the test set. Given that the comparison is against an NCCLS frozen Reference Panel, the reference panel itself serves as the agreed-upon gold standard, and individual results are compared directly to this standard. Discrepancies would typically be analyzed against established NCCLS criteria rather than through a separate adjudication panel for each case.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
There is no mention of a multi-reader multi-case (MRMC) comparative effectiveness study or any effect size of human readers improving with AI vs. without AI assistance. This device is a semi-automated system for determining Minimum Inhibitory Concentration (MIC) and involves visual reading, but the study focuses on the accuracy of the panel itself against a reference method rather than reader performance with or without AI assistance.
6. Standalone (Algorithm Only) Performance
The study primarily focuses on the standalone performance of the MicroScan® MICroSTREP plus™ Panel itself. It compares the device's MIC results to those of the NCCLS frozen Reference Panel. While the visual reading component involves human interpretation, the "acceptable performance with an overall Essential Agreement of 97.5% for Ceftriaxone" refers to the system's ability to produce accurate MIC values when interpreted according to its instructions. No human-in-the-loop enhanced performance is discussed as a separate variable.
7. Type of Ground Truth Used
The ground truth used was expert consensus (reference method), specifically the results obtained from an NCCLS frozen Reference Panel. This type of ground truth is a well-established and accepted standard in clinical microbiology for evaluating antimicrobial susceptibility testing devices.
8. Sample Size for the Training Set
The document does not specify a separate training set or its sample size. The study describes an "external evaluation" conducted to confirm acceptability by comparing performance with the NCCLS frozen Reference Panel, which typically refers to a validation or test set rather than a training set for model development.
9. How the Ground Truth for the Training Set Was Established
As no specific training set is mentioned as part of this device submission, the method for establishing its ground truth is not described. The focus of the provided information is on the reference standard used for validating the device's performance.
§ 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).