(63 days)
VITEK® 2 Streptococcus Clindamycin is designed for antimicrobial susceptibility testing of Streptococcus species. VITEK® 2 Streptococcus Clindamycin is a qualitative test 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. Clindamycin has been shown to be active in vitro against most strains of the microorganisms listed below, as described in the FDA-approved package insert for this antimicrobial agent.
Active in vitro and in clinical infections against:
Streptococcus pneumoniae (penicillin-susceptible strains) Streptococcus pyogenes
Active in vitro against:
Streptococcus agalactiae Streptococcus anginosus Streptococcus mitis Streptococcus oralis
The VITEK 2 Antimicrobial Susceptibility Test (AST) is intended to be used with the VITEK® 2 System for the automated quantitative or qualitative susceptibility testing of isolated colonies for the most clinically significant aerobic gram-negative bacilli, Staphylococcus spp., Enterococcus spp., Streptococcus spp. and clinically significant yeast.
The antimicrobial agent presented in the VITEK® 2 AST Cards is in concentrations equivalent by efficacy to standard method concentrations in mcg/ml. 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 - 0.50% 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 incubatorfreader. 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 36 hours for yeast). At the completion cycle, a report is generated that contains the MIC value along with the interpretive category result for each antibiotic contained on the card.
Here's an analysis of the provided text regarding the VITEK® 2 Streptococcus Clindamycin device, focusing on acceptance criteria and the supporting study:
The provided text describes a 510(k) submission for the VITEK® 2 Streptococcus Clindamycin, an antimicrobial susceptibility test. It outlines the device's purpose, the methodology, and the results of a study to demonstrate its performance.
Acceptance Criteria and Reported Device Performance
The acceptance criterion for the VITEK® 2 Streptococcus Clindamycin device, as stated, is based on achieving a certain level of agreement with a reference method.
| Acceptance Criterion | Reported Device Performance |
|---|---|
| Acceptable performance as defined in the FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA (August 28, 2009). Specifically, implied acceptable overall category agreement with the reference method. | 97.2% overall category agreement with the CLSI broth microdilution reference method. |
Details of the Study
2. Sample Size and Data Provenance
- Test Set Sample Size: The document mentions that an "external evaluation was conducted with fresh and stock clinical isolates, as well as a set of challenge strains." However, the exact number of isolates used in the test set is not explicitly stated in the provided text.
- Data Provenance: The provenance of the clinical isolates (e.g., country of origin) is not specified. The study involved both "fresh and stock clinical isolates," suggesting a mix of recently collected and archived samples. The study appears to be prospective in the sense that the VITEK® 2 device was tested against these isolates, but the collection of the "stock clinical isolates" would have been retrospective.
3. Number of Experts to Establish Ground Truth and Qualifications
The ground truth was established using the CLSI broth microdilution reference method. This method is a standardized laboratory procedure, not reliant on expert interpretation for its outcome. Therefore, the concept of "number of experts" and their "qualifications" for establishing ground truth in this context is not applicable. The ground truth is determined by the output of the reference assay itself.
4. Adjudication Method
As the ground truth was established by the CLSI broth microdilution reference method, an adjudication method is not applicable in the traditional sense of resolving discrepancies between human readers. The reference method provides a definitive result.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, an MRMC comparative effectiveness study was not done. This study assesses the performance of an automated device (VITEK® 2 system) against a standardized laboratory reference method, not against human readers. Therefore, there is no effect size reported for human readers improving with or without AI assistance.
6. Standalone Performance
Yes, a standalone performance study was done. The entire study described evaluates the VITEK® 2 Streptococcus Clindamycin as an "algorithm only" (automated test) system for determining antimicrobial susceptibility. Its performance (97.2% overall category agreement) is assessed independently against the reference standard.
7. Type of Ground Truth Used
The type of ground truth used was the CLSI broth microdilution reference method. This is a laboratory-based reference standard for determining minimum inhibitory concentrations (MICs) and susceptibility categories for antimicrobial agents.
8. Sample Size for the Training Set
The document does not provide information regarding a separate training set or its sample size. This type of submission (510(k) for an AST device) typically focuses on the performance of the finalized device against a reference method, rather than detailing the development and training phases of an algorithm in the way that, for example, an AI imaging device submission might.
9. How the Ground Truth for the Training Set Was Established
Since a training set is not explicitly mentioned or detailed, the method for establishing its ground truth is not provided in the text. Given the nature of AST devices, it's more likely that the system was developed using established microbiological principles and validated against reference standards, rather than "trained" on a discreet dataset with specific ground truth labels in a machine learning sense.
§ 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.”