(209 days)
VITEK® 2 AST-GP Cefoxitin Screen is designed to predict mecA-mediated oxacillin resistance in Staphylococcus spp. 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 Gram-Positive Susceptibility Card is intended for use with the VITEK® 2 Systems in clinical laboratories as an in vitro test to determine the susceptibility of Staphylococcus spp., Enterococcus spp., and Streptococcus agalactiae to antimicrobial agents when used as instructed.
VITEK® 2 AST-GP Cefoxitin Screen is designed to predict mecA-mediated oxacillin resistance in Staphylococcus spp. The cefoxitin screen and oxacillin work in combination to determine the final interpretation reported for oxacillin. The VITEK® 2 AST-GP Cefoxitin Screen is a qualitative test based on the CLSI, "Disk Diffusion Test for Prediction of mecAmediated resistance in Staphylococci." The VITEK® 2 AST-GP Cefoxitin Screen test 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 card is inoculated with a standardized organism suspension, and growth inside the card is optically monitored throughout the incubation cycle. Results are automatically calculated once a predetermined growth threshold is reached and a report is generated that contains the MIC result and the interpretive category result.
The principle of the VITEK® 2 AST cards is based on the microdilution minimum inhibitory concentration (MIC) technique reported by MacLowry and Marsh('') and Gerlach(2). The VITEK® 2 AST card is essentially a miniaturized, abbreviated and automated version of the doubling dilution technique(3).
Each VITEK® 2 AST card contains 64 wells. A control well which only contains microbiological culture media is resident on all cards. The remaining wells contain premeasured portions of a specific antibiotic combined with culture media. The bacterial or yeast isolate to be tested is diluted to a standardized concentration with 0.45 - 0.5% 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, sealing and loading operation. The VITEK® 2 Systems monitor the growth of each well in the card over a defined period of time. At the completion of the incubation cycle, a report is generated. For the VITEK 2 Cefoxitin Screen, the report will list either a positive or negative result. The VITEK 2 Cefoxitin Screen and oxacillin work in combination to determine the final oxacillin interpretation based on the CLSI recommendations.
NOTE: Final determination of the oxacillin interpretation is based on forcing rules as managed by the VITEK 2 Systems software. Both the VITEK 2 AST-GP Cefoxitin Screen test and Oxacillin test must finalize before any forcing rules are applied.
VITEK® 2 AST-GP Cefoxitin Screen has the following concentrations in the card: 4 and 5 ug/mL (equivalent standard method concentration by efficacy in ug/mL).
Here's a breakdown of the acceptance criteria and the study proving the device meets them, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
The device is a qualitative test designed to predict mecA-mediated oxacillin resistance in Staphylococcus spp. The performance is measured by Category Agreement (CA) and various error rates (Very Major Error - VME, Major Error - ME, Minor Error - mE).
| Antimicrobial + Cefoxitin Screen | Performance Metric | Acceptance Criteria (Implied by reported performance) | Reported Device Performance |
|---|---|---|---|
| S. aureus & S. lugdunensis | % Category Agreement (CA) | > 95% (common benchmark for AST devices) | 98.7% (525 / 532) |
| % Very Major Error (VME) | As low as possible, typically 95% (common benchmark for AST devices) | 97.8% (261 / 267) | |
| % Very Major Error (VME) | As low as possible, typically |
§ 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.”