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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:

VITEK® 2 Gram Positive Erythromycin for Streptococcus pneumoniae is designed for antimicrobial susceptibility testing of Gram positive Streptococcus pneumoniae and 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. VITEK 2 Gram Positive Erythromycin for Streptococcus pneumoniae is a qualitative test.

This submission is for the addition of an intermediate interpretive criteria.

Ervthromcvin has been shown to be active against the microorganisms listed below according to the FDA label for the antimicrobial.

Active in vitro and in clinical infections: Streptococcus pneumoniae

VITEK® 2 Gram Positive Erythromycin for Streptococcus pneumoniae is designed for antimicrobial susceptibility testing of Streptococus pneumoniae. 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 antimicrobial presented in VITEK 2 AST Cards is in concentrations equivalent by efficacy to standard method concentrations in mog/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% 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.

1. Table of Acceptance Criteria and Reported Device Performance

Note: The document states that the performance must be "substantially equivalent" to the CLSI broth microdilution reference method, as defined in the FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA, Issued Feb. 5, 2003. While specific numerical acceptance criteria (e.g., minimum percentage for category agreement, essential agreement) are often detailed within such guidance documents, they are not explicitly listed in this 510(k) summary. The summary highlights a "98.4% overall Category Agreement" as demonstrating "acceptable performance," implying this met their internal and regulatory expectations.

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

• Sample Size for Test Set: Not explicitly stated as an exact number in the provided text. The text mentions "fresh and stock clinical isolates and stock challenge strains" were used for an "external evaluation." The original 510(k) (K063492) that this submission refers to would contain the detailed sample size.
• Data Provenance: The data was from a retrospective analysis of clinical trial data that was part of the previous 510(k) (K063492). "There was no new clinical data gathered for this 510(k) notification." The country of origin is not specified but implicitly within the US given the submission to the FDA.

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

• Number of Experts: Not specified.
• Qualifications of Experts: Not specified.

4. Adjudication Method for the Test Set

• Adjudication Method: Not specified. The ground truth was established by the "CLSI broth microdilution reference method," which is a standard laboratory procedure, not typically involving human adjudication in the same way as, for example, image interpretation.

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

• MRMC Study Done: No. This device is an automated antimicrobial susceptibility testing system, not an imaging device requiring human reader interpretation or assistance. Therefore, an MRMC study comparing human readers with and without AI assistance is not applicable.

6. Standalone Performance Study

• Standalone Study Done: Yes. The study focused on the "algorithm only" performance (i.e., the VITEK 2 system) compared to the CLSI reference method. The VITEK 2 System is an automated device designed to provide a result without human intervention for interpretation beyond loading samples and reviewing the final report. The "overall Category Agreement" of 98.4% represents this standalone performance.

7. Type of Ground Truth Used

• Type of Ground Truth: The ground truth used was the CLSI broth microdilution reference method. This is a recognized standard laboratory method for determining minimum inhibitory concentrations (MICs) of antimicrobial agents.

8. Sample Size for the Training Set

• Sample Size for Training Set: Not applicable or specified. This submission is for a software algorithm change to utilize existing FDA breakpoints, re-analyzing previously collected clinical trial data. While the original device (K063492) would have had a development dataset, this specific submission does not involve new training of a machine learning model but rather a modification to how results are interpreted based on established breakpoints. The term "training set" is usually reserved for machine learning models, which is not what is being described here in the conventional sense.

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

• How Ground Truth for Training Set Was Established: Not applicable or specified for this submission. As mentioned above, this involves a re-analysis of existing data with a modified algorithm to apply FDA breakpoints, not the training of a new model. The ground truth for the original data was established using the CLSI broth microdilution reference method.

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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:

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.

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