(34 days)
VITEK® 2 Gram Positive Erythromycin for Streptococcus pneumoniae is designed for antimicrobial susceptibility testing of Streptococcus pneumoniae. VITEK 2 Gram Positive Erythromycin for Streptococcus pneumoniae is a qualitative 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 bacilii, 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.
Here's an analysis of the provided text regarding the acceptance criteria and study for the VITEK® 2 Gram Positive Erythromycin for Streptococcus pneumoniae device:
1. Table of Acceptance Criteria and Reported Device Performance:
| Acceptance Criteria Category | Acceptance Criteria (Implicit from FDA Guidance) | Reported Device Performance |
|---|---|---|
| Overall Category Agreement | Not explicitly stated, but typically ≥ 90% for AST systems. | 98.9% |
| Reproducibility | Acceptable results (implicit standard) | Acceptable results |
| Quality Control | Acceptable results (implicit standard) | Acceptable results |
Note: The document refers to "FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA, Issued Feb. 5, 2003" for defining acceptable performance. While specific numeric acceptance criteria for Category Agreement are not explicitly written in this extract, generally, for AST systems, a high percentage (e.g., >90%) of Category Agreement is expected for FDA clearance. The document states that the device "demonstrated substantially equivalent performance when compared with the CLSI broth microdilution reference method," indicating it met the implicit standards of this guidance.
2. Sample Size Used for the Test Set and Data Provenance:
- Sample Size: Not explicitly stated as a single number. The study used "fresh and stock clinical isolates and stock challenge strains." This suggests a diverse set of samples, but the total number is not provided.
- Data Provenance: The isolates included "fresh and stock clinical isolates" (implying real-world patient samples) and "stock challenge strains" (likely reference strains from culture collections). The country of origin is not specified, but bioMérieux is a multinational company with operations in the US. The study involved an "external evaluation," which could imply multi-center data collection or independent testing. It is a prospective evaluation comparing the device against a reference method.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts:
- The ground truth was established by the CLSI broth microdilution reference method. This is an objective laboratory method, not a subjective expert consensus. Therefore, the concept of "number of experts" or their qualifications for establishing ground truth as typically applied to image-based AI studies is not directly applicable here. The performance of the CLSI method itself is dependent on trained laboratory technicians adhering to standardized protocols.
4. Adjudication Method for the Test Set:
- None in the traditional sense. The comparison was directly between the VITEK 2 device's results (MIC values and interpretive categories) and the results from the CLSI broth microdilution reference method. Discrepancies would be analyzed against the standard, rather than adjudicated by human experts.
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. This is a study for an automated antimicrobial susceptibility testing (AST) device, which does not involve human "readers" in the diagnostic interpretation loop in the same way an image analysis AI would. The device automates a laboratory test. Its performance is compared to a reference laboratory method, not to human interpretation of data before and after AI assistance.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done:
- Yes. This study is a standalone performance evaluation of the VITEK 2 system. The VITEK 2 monitors growth and generates MIC values and interpretive categories autonomously. The study confirms its performance in this standalone capacity against the CLSI reference method.
7. The Type of Ground Truth Used:
- Objective Reference Method: The ground truth was established by the CLSI broth microdilution reference method. This is considered the gold standard for antimicrobial susceptibility testing.
8. The Sample Size for the Training Set:
- Not applicable / Not explicitly stated. This document describes a PMA/510(k) submission for a device, which historically did not involve "training sets" in the context of machine learning (AI) development. The VITEK 2 system operates based on established microbiological principles (growth detection) and pre-determined thresholds, rather than being "trained" on a large dataset in the AI sense. While there's an inherent development process that refines the algorithms, the document doesn't refer to a distinct "training set" like an AI model would have.
9. How the Ground Truth for the Training Set Was Established:
- Not applicable. As mentioned above, the concept of a "training set" with ground truth in the AI context isn't directly applicable here. The system's underlying science is based on established microbiological principles, and its performance parameters are likely derived from extensive R&D and validation studies, not from a singular "training set" with independently established ground truth in the AI machine learning paradigm.
§ 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.”