(91 days)
The VITEK® 2 Gram Positive AST Panel for Streptococcus pneumoniae: Levofloxacin is intended for use with the VITEK® 2 System in clinical laboratories as an in vitro test to determine the susceptibility of Streptococcus pneumoniae to antimicrobial agents. The antimicrobial presented in the VITEK® 2 AST panel is in concentrations equivalent by efficacy to standard method concentrations in mcg/ml.
The VITEK 2 Gram Positive AST Panel for Streptococcus pneumoniae: Levofloxacin is intended for use with the VITEK® 2 System in clinical laboratories as an in vitro test to intendou the susceptibility of Streptococcus pneumoniae to antimicrobial agents. The antimicrobial presented in the VITEK® 2 AST panel is in concentrations equivalent by afficacy to standard method concentrations in mcg/ml. The AST panels are essentially miniaturized versions of the doubling dilution technique for determining the minimum inhibitory concentration (MIC) my microdilution methodology.
The VITEK 2 system automatically fills the AST panels with a standardized organism suspension. The organism suspension may either be prepared automatically by the VITEK 2 or prepared manually. The filled AST panels are automatically sealed and loaded into the optical reader/incubator. Temperature is monitored and controlled throughout the incubation cycle. Organism growth in the test panel is continually monitored by the optical system. Optical readings are transformed by the VITEK 2 System into antimicrobial MIC's and category (Sensitive/Intermediate/Resistant) interpretations.
Here's a breakdown of the acceptance criteria and study details for the VITEK® 2 Gram Positive AST Panel for Streptococcus pneumoniae: Levofloxacin, based on the provided text:
Acceptance Criteria and Device Performance
| Acceptance Criteria | Reported Device Performance |
|---|---|
| Acceptable performance when compared with an NCCLS frozen Reference Panel, as defined in the FDA DRAFT document "Guidance on Review Criteria for Assessment of Antimicrobial susceptibility Devices", dated March 8, 2000. | 99.8% overall Essential Agreement with automatic dilution when compared to the frozen reference panel. |
| Acceptable reproducibility (for both automatic and manual dilution methods). | Demonstrated acceptable reproducibility. |
| Acceptable Quality Control results. | Demonstrated acceptable Quality Control results. |
Study Details
2. Sample size used for the test set and the data provenance:
- Test set: The text mentions an "external evaluation ... with fresh and stock clinical isolates and stock challenge strains." However, the exact sample size for these strains is not specified.
- Data Provenance: The study involved an "external evaluation," suggesting data was collected from sources outside the direct developer's lab, but specific countries of origin are not mentioned. It involved both "fresh and stock clinical isolates," implying a mix of retrospective (from existing collections) and potentially prospective (newly collected) samples.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- The ground truth for the test set was established by comparing the VITEK® 2 system's performance to an "NCCLS frozen reference panel." This reference panel itself would have established MICs. The text does not specify the number or qualifications of experts involved in creating or verifying the NCCLS frozen reference panel or its expected results.
4. Adjudication method (e.g., 2+1, 3+1, none) for the test set:
- The text does not describe an adjudication method in the traditional sense of multiple human readers or experts resolving discrepancies. The comparison was directly to an "NCCLS frozen reference panel" (and "Expected Result" for challenge strains), which implies a pre-established, authoritative ground truth rather than a process of reaching consensus among experts for each test case.
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, a multi-reader multi-case (MRMC) comparative effectiveness study was not conducted. This device is an automated antimicrobial susceptibility testing system, not an AI-assisted diagnostic tool for human readers. Its performance is evaluated against a reference method.
6. If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:
- Yes, a standalone performance evaluation was conducted. The VITEK® 2 system is essentially an "algorithm only" device (an automated system) that determines susceptibility without human intervention in the interpretation of the primary optical readings. The study evaluated its performance in this standalone capacity.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
- The primary ground truth used was the results from an NCCLS frozen Reference Panel. For "challenge strains," the ground truth was an "Expected Result," which would presumably also be derived from a validated reference method or expert consensus for those specific strains. This is a type of reference standard.
8. The sample size for the training set:
- The document does not provide information regarding a distinct "training set" or its sample size. The VITEK® 2 system's underlying algorithms and concentrations would have been developed and validated over time, but the specific 510(k) summary focuses on the clinical validation (test set performance) of this specific panel against a reference method.
9. How the ground truth for the training set was established:
- As no training set is explicitly described, there is no information on how its ground truth would have been established. Any underlying development work for the VITEK® 2 system's broader technology would likely have involved extensive testing against reference methods (like microdilution or agar dilution) to establish accurate MICs and interpretive categories.
§ 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.”