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VITEK 2® Gram Positive Moxifloxacin is designed for antimicrobial susceptibility testing of Staphylococcus aureus (methicillin-susceptible strains only). It is intended for use with the VITEK 2® System as a laboratory aid in the determination of in vitro susceptibility to antimicrobial agents.

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 automatically fills, seals and places the card into the incubator/reader. 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 a summary of the acceptance criteria and study details for the VITEK® 2 Gram Positive Moxifloxacin, based on the provided text:

1. Acceptance Criteria and Reported Device Performance:

2. Sample Size Used for the Test Set and Data Provenance:

The document mentions "fresh and stock clinical isolates and stock challenge strains". It does not explicitly state the exact sample size for the test set.

• Data Provenance: Not explicitly stated, though the mention of "external evaluation" suggests multiple sites, potentially within the USA, given the FDA submission. The letter from the FDA does state "Over the country USA" likely referring to the manufacturer's location, rather than data provenance.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts:

The ground truth was established using the NCCLS reference agar dilution method. This is a standardized laboratory method for determining antimicrobial susceptibility, not directly an expert consensus in the typical sense (e.g., a panel of radiologists). While laboratories performing this method require trained personnel, the document does not specify the number of individuals or their specific qualifications beyond adherence to the NCCLS standard.

4. Adjudication Method for the Test Set:

Not applicable. The comparison was made against a standardized laboratory reference method (NCCLS agar dilution), not human expert interpretations requiring adjudication.

5. Multi Reader Multi Case (MRMC) Comparative Effectiveness Study:

No, an MRMC study was not performed. This device is an automated antimicrobial susceptibility testing system, not an imaging or diagnostic AI requiring human-in-the-loop performance evaluation.

6. Standalone Performance:

Yes, a standalone performance study was done. The VITEK® 2 Gram Positive Moxifloxacin was compared directly against the NCCLS reference agar dilution method to determine its "Essential Agreement."

7. Type of Ground Truth Used:

The ground truth used was the NCCLS reference agar dilution method. This is a validated laboratory method considered the gold standard for determining minimum inhibitory concentration (MIC) and susceptibility in microbiology.

8. Sample Size for the Training Set:

The document does not explicitly mention a separate "training set" or its size. The described validation study details an "external evaluation" that tested the VITEK® 2 system. For such automated systems, "training" might refer to the development and calibration of the algorithm itself using internal data, which would likely have preceded this external validation study.

9. How the Ground Truth for the Training Set Was Established:

As no explicit training set is detailed, the method for establishing its ground truth is not provided. If the device's algorithms were developed internally, it's highly probable they were trained against similar reference methods (like agar dilution) to establish accurate MIC readings and interpretive categories.

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VITEK® 2 Gram Positive Moxifloxacin for Streptococcus pneumoniae is designed for antimicrobial susceptibility testing of Streptococcus pneumoniae. It is intended for use with the VITEK® 2 System as a laboratory aid in the determination of in vitro susceptibility to antimicrobial agents.

The VITEK 2 AST Cards are essentially miniaturized versions of the doubling dilution technique for determining the minimum inhibitory concentration (MIC) my 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 automatically fills, seals and places the card into the incubator/reader. 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 VITEK® 2 Gram Positive Moxifloxacin for Streptococcus pneumoniae device, focusing on acceptance criteria and supporting study details:

1. Table of Acceptance Criteria and Reported Device Performance:

The document refers to "acceptable performance" as defined in the Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; guidance for Industry and FDA. Issued February 5, 2003. While the specific numerical acceptance criteria from this guidance document are not explicitly detailed in the provided text, the device's performance against these unstated criteria is reported.

Note: The exact numerical thresholds for "Acceptable" for Reproducibility and Quality Control are not specified in the provided text but would be defined in the referenced FDA guidance document.

2. Sample Size Used for the Test Set and Data Provenance:

• Sample Size for Test Set: Not explicitly stated in terms of a specific number of isolates. The document mentions "fresh and stock clinical isolates and stock challenge strains" were used in the external evaluation.
• Data Provenance: Not explicitly stated (e.g., country of origin). The study involved "external evaluations," implying multiple locations, but specific geographic details are absent. The isolates were a mix of "fresh and stock clinical isolates" (implying retrospective and potentially prospective clinical samples) and "stock challenge strains."

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications:

• Number of Experts: Not specified.
• Qualifications of Experts: Not specified. The ground truth was established by the NCCLS reference microbroth dilution method. While this method is performed by laboratory personnel, the document does not specify if "experts" (e.g., microbiologists with specific experience) formally established or adjudicated the ground truth results, beyond adhering to the standard method.

4. Adjudication Method for the Test Set:

• Adjudication Method: Not explicitly described. The primary method for establishing ground truth was the NCCLS reference microbroth dilution method. This method inherently provides a reference result, and the document does not mention a separate adjudication process for reconciling differing interpretations between multiple readers or methods.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done:

• No, an MRMC comparative effectiveness study was not explicitly described. The study focused on comparing the VITEK® 2 system's performance against a reference method (NCCLS microbroth dilution), not on the improvement of human readers with AI assistance.

6. If a Standalone (Algorithm Only Without Human-in-the-Loop Performance) Was Done:

• Yes, a standalone performance evaluation was done. The VITEK® 2 system is an automated device ("algorithm only" in the sense that it automatically processes and interprets results without direct human intervention in the interpretation of that specific test). Its performance was compared directly to the NCCLS reference method. The "report is generated that contains the MIC value along with the interpretive category result for each antibiotic contained on the card," indicating an automated output.

7. The Type of Ground Truth Used:

• Type of Ground Truth: The ground truth was established using the NCCLS reference microbroth dilution method. This is considered a gold standard in vitro laboratory method for antimicrobial susceptibility testing.

8. The Sample Size for the Training Set:

• Sample Size for Training Set: Not explicitly stated. The document describes an "external evaluation" for confirming acceptability, but it does not detail a separate training phase or the size of a training dataset. Given this is a 510(k) for an AST device, the "training" (development and refinement) of the AST algorithm would likely have involved extensive historical data and might not be documented as a distinct "training set" in the same way an AI/ML model for image interpretation would be.

9. How the Ground Truth for the Training Set Was Established:

• How Ground Truth for Training Set Was Established: Not explicitly stated. If there was an internal training or development phase, it's highly probable that the ground truth for that phase would also have been established using the NCCLS reference microbroth dilution method, as it is the accepted standard. However, the document does not provide details on this.

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