(24 days)
VITEK® 2 Gram Positive Vancomycin is designed for antimicrobial susceptibility testing of Enterococcus species, Staphylococcus species and Streptococcus agalactiae. VITEK 2 Gram Positive Vancomycin is a quantitative test. It is intended for use with the VITEK 2 and VITEK 2 Compact Systems as a laboratory aid in the determination of in vitro susceptibility to antimicrobial agents.
The VITEK® 2 Antimicrobial Susceptibility Test (AST) is intended to be used with the VITEK® 2 and VITEK® 2 Compact Systems for the automated quantitative or qualitative susceptibility testing of isolated colonies for the most clinically significant aerobic gramnegative bacilli, Staphylococcus spp., Enterococcus spp., Streptococcus agalactiae, and S. pneumoniae.
The VITEK 2 AST Cards are essentially miniaturized versions of the doubling dilution technique for determining the minimum inhibitory concentration (MIC) microdilution methodology. The bacterial isolate to be tested is diluted to a standardized concentration in 0.45% saline before being used to rehydrate the antimicrobial medium within the card. The VITEK 2 System automatically fills, seals and places the card into the incubator/reader. The VITEK 2 Compact has a manual filling and sealing operation. The VITEK 2 monitors the growth of each well in the card over a defined period of time (up to 18 hours). At the completion of the incubation cycle, a report is generated that contains the MIC value along with the interpretive category result for each antibiotic contained on the card.
The following information describes the acceptance criteria and study proving the device meets those criteria:
1. Acceptance Criteria and Reported Device Performance:
| Criteria | Acceptance Criteria | Reported Device Performance |
|---|---|---|
| Overall Category Agreement | Not explicitly stated (implied acceptable performance) | 99.6% |
| Reproducibility | Not explicitly stated (implied acceptable results) | Acceptable results |
| Quality Control | Not explicitly stated (implied acceptable results) | Acceptable results |
2. Sample Size and Data Provenance:
- Test Set Sample Size: Not explicitly stated, but the study involved "fresh and stock clinical isolates and stock challenge strains."
- Data Provenance: Not explicitly stated, but the isolates appear to be clinical, meaning they likely originated from various clinical settings. Given the submitter's location (Hazelwood, MO, USA), it's highly probable the data is primarily from the USA. The study design as described ("external evaluation") suggests the data was collected for the purpose of validating the device, indicating a prospective or at least a controlled retrospective design.
3. Number of Experts and Qualifications:
- Number of Experts: Not specified.
- Qualifications of Experts: Not specified. The reference method used was the CLSI broth microdilution, which is a standardized laboratory method, not typically adjudicated by clinical experts in the same way imaging studies might be. The "experts" would likely be trained microbiologists performing and interpreting the reference method.
4. Adjudication Method for the Test Set:
- Adjudication Method: Not applicable in the traditional sense. The comparison was against the CLSI broth microdilution reference method, which is a standardized, objective laboratory assay. Any discrepancies between the VITEK 2 device and the reference method would be analyzed, but there isn't a "human adjudication" process as seen in imaging studies.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study:
- MRMC Study: No, an MRMC comparative effectiveness study was not conducted as this device is an automated antimicrobial susceptibility test system, not an imaging analysis tool requiring human interpretation/reading. Therefore, there's no "human readers get better with AI assistance" effect size to report.
6. Standalone Performance:
- Standalone Performance: Yes, the study evaluated the "standalone" performance of the VITEK® 2 Gram Positive Vancomycin device by comparing its results directly with the CLSI broth microdilution reference method. The device's ability to determine MIC values and interpretive categories was assessed independently of human intervention during the test itself.
7. Type of Ground Truth Used:
- Ground Truth Type: Expert consensus on the CLSI broth microdilution reference method. The "gold standard" for determining antimicrobial susceptibility in this context is the Clinical and Laboratory Standards Institute (CLSI) broth microdilution reference method.
8. Sample Size for the Training Set:
- Training Set Sample Size: Not specified in the provided summary. The summary focuses on the external evaluation/test set.
9. How the Ground Truth for the Training Set Was Established:
- Training Set Ground Truth Establishment: Not specified in the provided summary. However, for AST devices, training data ground truth would typically be established using a similar, if not identical, reference method as the test set (i.e., CLSI broth microdilution) to ensure consistency and accuracy in developing the device's algorithms.
§ 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.”