(22 days)
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.
To determine bacterial antimicrobial agent susceptibility
This particular submission is for the addition of instrument read capability of the antimicrobial Cefotaxime, at concentrations of 0.015 -8 mcg/ml on the MicroScan MICroSTREP plus® Panel.
The organisms which may be used for Cefotaxime susceptibility testing in this panel are:
Streptococcus pneumoniae Streptococcus pyogenes (Group A beta-hemolytic streptococci) Streptococcus spp.
The MicroScan MICroSTREP plus® Panel is used to determine quantitative and/or qualitative r no microbial 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 ℃ 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 Muellerecontractle 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.
Here's a breakdown of the acceptance criteria and study information for the MicroScan MICroSTREP plus® Panel with Cefotaxime, based on the provided text:
Acceptance Criteria and Device Performance
| Acceptance Criteria | Reported Device Performance |
|---|---|
| Overall Essential Agreement with Expected Result | 93% Essential Agreement for Cefotaxime instrument read results compared with the Expected Result |
| Instrument Reproducibility | Demonstrated acceptable reproducibility and precision |
| Quality Control Testing | Demonstrated acceptable results for Cefotaxime |
Note: The specific numerical target for "acceptable" essential agreement and other metrics is not explicitly stated but is implicitly met by the reported 93% and "acceptable" statements. The reference to the "Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA", dated February 5, 2003, would contain the detailed numerical acceptance criteria.
Study Information
2. Sample size used for the test set and the data provenance:
- Test Set Sample Size: The text states "The evaluation was conducted with stock and CDC Challenge strains." However, the exact number of strains or isolates used in the test set is not specified in the provided document.
- Data Provenance:
- Country of Origin: Not specified.
- Retrospective or Prospective: Not explicitly stated, but the phrase "The evaluations were designed to confirm the acceptability of the proposed instrument read method... by comparing its performance with Expected Results determined before the evaluation" suggests a prospective comparison against pre-defined expected results.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- Number of Experts: Not specified.
- Qualifications of Experts: Not specified.
- Role of Experts: The ground truth was referred to as "Expected Results determined before the evaluation" and was based on "a CLSI frozen Reference Panel." This implies the ground truth was established by a recognized standard methodology (CLSI) and likely involved expert consensus in establishing the reference panel.
4. Adjudication method for the test set:
- Adjudication method is not specified. The comparison was against "Expected Results determined before the evaluation" and a "CLSI frozen Reference Panel."
5. If a multi-reader multi-case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:
- No, an MRMC comparative effectiveness study was not done. This study focuses on validating the instrument-read capability of an antimicrobial susceptibility test panel against a predicate device/reference standard, not on human-AI collaboration or improvement with AI assistance. The "instrument read method" refers to the automated reading by the MicroScan WalkAway instrument.
6. If a standalone (i.e. algorithm only without human-in-the loop performance) was done:
- Yes, a standalone performance study was done. The entire premise of the submission is to validate the "instrument read method" (MicroScan WalkAway instrument) for the MICroSTREP plus® Panel for Cefotaxime. This is a standalone assessment of the automated instrument's performance in reading the Minimum Inhibitory Concentration (MIC) values.
7. The type of ground truth used:
- The ground truth used was Expert Consensus/Reference Standard. It was based on "Expected Results determined before the evaluation" which were generated on a "CLSI frozen Reference Panel." The CLSI (Clinical and Laboratory Standards Institute) provides recognized standards for microbiology testing, and reference panels are established through rigorous testing and expert consensus to provide a reliable "true" value.
8. The sample size for the training set:
- Not applicable/Not specified. This type of device (Antimicrobial Susceptibility Test System based on broth microdilution) typically does not involve a "training set" in the machine learning sense. The "training" of the instrument is inherent in its design and calibration for reading growth inhibition, rather than a data-driven training phase to learn a specific task. The validation focuses on the instrument's performance against established reference methods.
9. How the ground truth for the training set was established:
- Not applicable/Not specified. As mentioned above, a "training set" in the AI sense is not relevant for this device.
§ 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).