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VITEK 2 AST-Gram Negative Cefazolin is designed for antimicrobial susceptibility testing of Gram-negative bacilli and is intended for use with the VITEK 2 Systems as a laboratory aid in the determination of in vitro susceptibility to antimicrobial agents.

VITEK 2 AST-Gram Negative Cefazolin (≤1-≥32 µg/mL) is a quantitative test. Testing is indicated for Enterobacterales (from infections other than uncomplicated UTI) as recognized by the FDA Susceptibility Test Interpretive Criteria (STIC).

VITEK 2 AST-Gram Negative Cefazolin (≤1-≥32 µg/mL) has demonstrated acceptable performance with the following organisms:

Enterobacterales (Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae, Klebsiella oxytoca, Citrobacter koseri)

The VITEK 2 Gram Negative Susceptibility Card is intended for use with the VITEK 2 Systems in clinical laboratories as an in vitro test to determine the susceptibility of clinically significant aerobic Gram- negative bacilli to antimicrobial agents when used as instructed.

The principle of the VITEK® 2 AST cards is based on the microdilution minimum inhibitory concentration (MIC) technique reported by MacLowry and Marsh (1) 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 that contains the MIC value along with the interpretive category result for each antibiotic contained on the card.

VITEK® 2 AST-GN Cefazolin has the following concentrations in the card: 1, 2, and 8 (equivalent standard method concentration by efficacy in µg/mL).

The provided text describes the acceptance criteria and a study proving the device meets these criteria for the VITEK 2 AST-Gram Negative Cefazolin antimicrobial susceptibility testing system.

Here's a breakdown of the requested information:

1. Table of Acceptance Criteria and Reported Device Performance

Note on Acceptance Criteria: The document references the "FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA (Issued August 28, 2009)" for defining acceptable performance. While specific numerical acceptance criteria (e.g., for EA, CA, VME, ME) are not explicitly listed in the provided text, they are implied by the reported performance metrics and the statement that the device "demonstrated substantially equivalent performance." For AST systems, the FDA typically looks for high Essential and Category Agreement, with very low rates of Major and Very Major Errors. The low Category Agreement (86.8%) is acknowledged and attributed mainly to minor errors.

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

• Sample Size for Test Set:
  • Total isolates tested: 862 (derived from the denominator for EA and CA calculations).
  • The study included "fresh and stock clinical isolates" as well as "a set of challenge strains."
• Data Provenance:
  • The study was an "external evaluation." This typically implies data collected from multiple sites outside of the manufacturer's primary lab.
  • The document does not specify the country of origin for the data.
  • The study included both "fresh" and "stock" clinical isolates, suggesting a mix of prospective (fresh isolates) and retrospective (stock isolates) data collection.

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

The document does not specify the number or qualifications of experts used to establish the ground truth.

4. Adjudication Method for the Test Set

The document does not describe an adjudication method for the test set. For AST devices, the "ground truth" is typically established by a reference method (broth microdilution in this case), not by expert consensus or adjudication in the way it might be for an imaging AI device.

5. If a Multi Reader Multi Case (MRMC) Comparative Effectiveness Study Was Done, and Effect Size of Improvement

No, a Multi Reader Multi Case (MRMC) comparative effectiveness study was not performed. This type of study (human readers assisting vs. not assisting) is typically relevant for interpretative diagnostic devices, especially in imaging, where human interpretation is a key part of the workflow. The VITEK 2 AST system is an automated device for determining antimicrobial susceptibility, not directly for human interpretation or image reading.

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

Yes, the primary performance study presented is a standalone (algorithm only) performance study. The device's performance (VITEK 2 AST-GN Cefazolin) was compared directly against the CLSI broth microdilution reference method. There is no mention of human-in-the-loop performance evaluation, as the VITEK 2 system is automated.

7. The Type of Ground Truth Used

The type of ground truth used was: Reference Method Comparison.
Specifically, the performance of the VITEK 2 AST-GN Cefazolin was compared to the CLSI broth microdilution reference method, incubated for 16-20 hours. This is the gold standard for antimicrobial susceptibility testing.

8. The Sample Size for the Training Set

The document does not specify the sample size for the training set. This submission is for a 510(k) clearance, which typically focuses on the performance of the final device rather than the specifics of its development (like training data for AI/ML models). The VITEK 2 system relies on growth pattern analysis algorithms rather than deep learning models that require large, labeled training datasets in the conventional sense. Its "training" would likely involve optimizing these algorithms based on extensive internal validation.

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

The document does not describe how the ground truth for the training set was established, as details on the development of the device's analysis algorithms (likely proprietary) are not typically included in a 510(k) summary. Given the nature of AST systems, any "ground truth" used during development would also likely stem from comparisons to established reference methods like broth microdilution, similar to the test set's ground truth.

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VITEK 2 AST-Yeast Voriconazole is designed for antifungal susceptibility testing of Candida species 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 antifungal agents. VITEK 2 AST-Yeast Voriconazole is a quantitative test. Voriconazole has been shown to be active against most strains of the microorganisms listed below, according to the FDA label for this antifungal.

Active in vitro and in clinical infections: Candida krusei Candida parapsilosis Candida tropicalis

The VITEK 2 Fungal Susceptibility Card is intended for use with the VITEK 2 Systems in clinical laboratories as an in vitro test to determine the susceptibility of clinically significant yeasts to antifungal agents when used as instructed.

The principle of the VITEK® 2 AST cards is based on the microdilution minimum inhibitory concentration (MIC) technique. The VITEK® 2 AST card is essentially a miniaturized, abbreviated and automated version of the doubling dilution technique. 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 that contains the MIC value along with the interpretive category result for each antibiotic contained on the card.

VITEK® 2 AST-YS Voriconazole has the following concentrations in the card: 0.03125, 0.125, 0.25, 1, and 2 (equivalent standard method concentration by efficacy in ug/mL).

The provided FDA 510(k) summary describes the VITEK® 2 AST-Yeast Voriconazole device, which is an antimicrobial susceptibility test system.

Here's an analysis of the acceptance criteria and the study that proves the device meets them:

1. Table of Acceptance Criteria and Reported Device Performance:

The acceptance criteria are implicitly derived from the FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems and are presented through "Essential Agreement" (EA) and "Category Agreement" (CA) performance metrics, along with error rates. The table below summarizes the reported performance for each microorganism. The specific acceptance thresholds for EA and CA are not explicitly stated as numerical percentages (e.g., >90% EA, >90% CA) with the exception of the individual error types (VME, ME, mE) having specified maximum allowable percentages. However, it is implied that the presented results were deemed acceptable by the FDA.

Key Definitions:

• Essential Agreement (EA): Agreement between the MIC results of the test device and the reference method within plus or minus one doubling dilution.
• Category Agreement (CA): Agreement between the interpretive categories (Susceptible, Intermediate, Resistant) of the test device and the reference method.
• Very Major Error (VME): The test device reports susceptible, but the reference method reports resistant.
• Major Error (ME): The test device reports resistant, but the reference method reports susceptible.
• Minor Error (mE): Any other disagreement in interpretive category (e.g., susceptible vs. intermediate, resistant vs. intermediate).

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

The sample sizes for the test set (external evaluation) are provided for each microorganism:

• C. albicans: 257 isolates
• C. krusei: 76 isolates
• C. parapsilosis: 74 isolates
• C. tropicalis: 87 isolates

Data Provenance: The study conducted an "external evaluation" with "fresh and stock clinical isolates, as well as a set of challenge strains." The document does not specify the country of origin of the data nor explicitly state if it was retrospective or prospective. However, "fresh clinical isolates" typically implies a prospective collection, while "stock clinical isolates" could be either.

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

The ground truth was established by the "CLSI broth microdilution reference method." This is a standardized laboratory method, not reliant on human expert adjudication in the same way an imaging study would be. Therefore, the concept of "experts" and their qualifications as typically applied to visual diagnostic tasks (e.g., radiologists) is not directly applicable here. The ground truth method itself (CLSI broth microdilution) is the expert-defined standard.

4. Adjudication Method for the Test Set:

Not applicable in the human expert sense. The "adjudication method" for determining the ground truth in this context is the CLSI broth microdilution reference method, which serves as the gold standard for antimicrobial susceptibility testing. The device's results are compared directly against this established reference.

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

No, an MRMC comparative effectiveness study was not done. This type of study is relevant for diagnostic devices where human readers interpret results, often in conjunction with AI. The VITEK® 2 AST-Yeast Voriconazole is an automated in vitro diagnostic device for antimicrobial susceptibility testing; its performance is evaluated by comparing its automated output to a gold standard laboratory method, not by how it assists human readers.

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

Yes, a standalone performance evaluation was done. The VITEK® 2 AST-Yeast Voriconazole system is an automated device designed to determine antimicrobial susceptibility without human interpretation of the primary data once the sample is loaded. The performance metrics (Essential Agreement, Category Agreement, error rates) directly reflect the device's standalone capability compared to the reference method.

7. The Type of Ground Truth Used:

The ground truth used was the CLSI broth microdilution reference method, incubated for 24 hours (up to 48 hours for slowly growing isolates). This is a well-established and scientifically accepted standard in microbiology for determining minimum inhibitory concentrations (MICs) of antifungal agents.

8. The Sample Size for the Training Set:

The document does not explicitly state the sample size for the training set. The descriptions focus on the "external evaluation" (test set). For IVD devices like this, the 'training set' often corresponds to historical data, internal studies, and method development efforts that lead to the final algorithm and concentration ranges. Without further information, the exact size of the training set used to develop the VITEK® 2 AST-Yeast Voriconazole algorithm is not provided in this 510(k) summary.

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

Similar to the answer for point 8, the document does not explicitly describe how the ground truth for any potential training set was established. However, given that the final performance is benchmarked against the CLSI broth microdilution reference method, it is highly probable that any internal development or training data would also have used this or a similar established reference method to determine the true susceptibility of isolates.

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VITEK 2 AST-Yeast Anidulafungin is designed for antifungal susceptibility testing of Candida species 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 antifungal agents. VITEK 2 AST-Yeast Anidulafungin is a quantitative test. Anidulafungin has been shown to be active against most strains of the microorganisms listed below, according to the FDA label for this antifungal.

Active in vitro and in clinical infections: Candida albicans Candida glabrata Candida parapsilosis Candida tropicalis

In vitro data are available, but clinical significance is unknown: Candida guillermondii Candida krusei

The VITEK 2 Fungal Susceptibility Card is intended for use with the VITEK 2 Systems in clinical laboratories as an in vitro test to determine the susceptibility of clinically significant yeasts to antifungal agents when used as instructed.

The principle of the VITEK® 2 AST cards is based on the microdilution minimum inhibitory concentration (MIC) technique reported by MacLowry and Marsh (1) 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 that contains the MIC value along with the interpretive category result for each antibiotic contained on the card.

VITEK® 2 AST-YS Anidulafungin has the following concentrations in the card: 0.0625, 0.125, 0.5, 2, and 8 (equivalent standard method concentration by efficacy in ug/mL).

Here's an analysis of the acceptance criteria and the study proving the device meets those criteria, based on the provided text.

Device: VITEK 2 AST-Yeast Anidulafungin

Indications for Use: Antifungal susceptibility testing of Candida species (C. albicans, C. glabrata, C. parapsilosis, C. tropicalis, C. guilliermondii, C. krusei) as a laboratory aid in determining in vitro susceptibility to antifungal agents.

1. Table of Acceptance Criteria and Reported Device Performance

The provided document doesn't explicitly state the acceptance criteria in a separate table directly defining thresholds for Essential Agreement (EA), Category Agreement (CA), or error rates (VME, ME, mE) that the device must meet for approval. Instead, it presents the results of the performance study and implies that these results were deemed "acceptable" by the FDA. The performance is compared 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 August 28, 2009)". This guidance document would contain the specific acceptance criteria.

However, based on the presented "Performance Overview" (Page 7) and the overall context of AST device approvals, typical acceptance criteria for Essential Agreement and Category Agreement are usually in the range of 90-95% or higher, with Very Major Error (VME) and Major Error (ME) rates usually being low (e.g., <3% or <1.5%).

Here's the reported device performance:

Note on C. tropicalis VME: The document specifically highlights: "When evaluating VITEK 2 AST-YS Anidulafungin, there was a single very major error (VMJ) that resulted in an unacceptable VMJ rate of 33.3% (1/3) with C. tropicalis." Despite this, the overall conclusion states "VITEK® 2 AST-YS Anidulafungin demonstrated acceptable performance." This suggests that either the unacceptably high VME for C. tropicalis was mitigated by other factors (e.g., small sample size for VME calculation, or specific post-market surveillance requirements), or it points to a known limitation that the FDA found acceptable for clearance under the stated conditions.

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

• Sample Size for Test Set:

  • C. albicans: 206 isolates
  • C. glabrata: 116 isolates
  • C. guilliermondii: 21 isolates
  • C. krusei: 69 isolates
  • C. parapsilosis: 72 isolates
  • C. tropicalis: 81 isolates
  • Total Isolates: 565 isolates across the specified Candida species.

• Data Provenance: The study involved an "external evaluation" conducted with "fresh and stock clinical isolates, as well as a set of challenge strains." The document does not specify the country of origin of the data or whether it was retrospective or prospective. Typically, "clinical isolates" imply prospective collection from real patient samples, and "stock isolates" could be reference strains or previously collected clinical isolates. "External evaluation" implies data was collected from multiple sites, which is standard for clinical trials of this nature.

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

This information is not provided in the document. For antimicrobial susceptibility testing (AST) devices, the ground truth is established by a reference method (here, the CLSI broth microdilution reference method), not by human expert interpretation of images or data in a consensus setting.

4. Adjudication Method for the Test Set

Not applicable. The ground truth for AST devices is established by a standardized laboratory reference method (CLSI broth microdilution), not through expert adjudication of ambiguous cases like in imaging studies.

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

No, an MRMC comparative effectiveness study was not performed. This type of study (comparing human readers with and without AI assistance on diagnostic tasks) is not relevant for an automated antimicrobial susceptibility testing device like the VITEK 2 AST-Yeast Anidulafungin. This device provides quantitative MIC values and interpretive categories, not an interpretation of a medical image or clinical data that would involve human readers.

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

Yes, the performance study effectively evaluates the standalone performance of the VITEK 2 AST-Yeast Anidulafungin system. The device automatically reads and interprets the growth patterns in the microdilution wells to generate MIC values and interpretive categories (Susceptible, Intermediate, Resistant). This automated result is then compared directly to the established ground truth (CLSI broth microdilution reference method). While human operators physically load the cards, the core performance being evaluated is the device's automated analysis.

7. The Type of Ground Truth Used

The type of ground truth used was the CLSI broth microdilution reference method (Clinical and Laboratory Standards Institute). This is a well-established, standardized, and validated laboratory method for determining the minimum inhibitory concentration (MIC) of an antimicrobial agent against a microorganism. The reference method results serve as the "gold standard" for accuracy in AST device performance studies.

8. The Sample Size for the Training Set

The document does not provide specific details about the training set size. The device uses "Discriminant Analysis" algorithms. Typically, for a device like this, the algorithms would be developed and refined using a large dataset of isolates with known reference MICs to optimize the mapping between the device's optical measurements and the true MICs. However, the exact size of this internal development/training set is not disclosed in this summary. The provided performance data (the "test set") is for validation purposes, distinct from the training set.

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

While not explicitly stated for a "training set" in this document, it is highly probable that the ground truth for any isolates used during the development and training of the VITEK 2 system's algorithms would also have been established using the CLSI broth microdilution reference method or similar highly standardized and validated laboratory methods, consistent with industry best practices for AST device development. This ensures that the algorithm learns from accurate data.

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VITEK® 2 AST-Gram Positive Lefamulin is designed for antimicrobial susceptibility testing of Gram positive microorganisms 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 AST-Gram Positive Lefamulin is a quantitative test. Lefamulin has been shown to be active against most strains of the microorganisms listed below, according to the FDA label for this antimicrobial.

Active both in vitro and in clinical infections: Staphylococcus aureus (methicillin-susceptible isolates)

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., and S. agalactive to antimicrobial agents when used as instructed.

The principle of the VITEK® 2 AST cards is based on the microdilution minimum inhibitory concentration (MIC) technique reported by MacLowry and Marsh (1) and Gerlach (2). The VITEK® 2 AST card is essentially a miniaturized, abbreviated and automated version of the doubling dilution technique (0).

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 that contains the MIC value along with the interpretive category result for each antibiotic contained on the card.

VITEK® 2 AST-GP Lefamulin (≤ 0.03 –>4 µg/mL) has the following concentrations in the card: 0.125, 0.5, 1, and 2 (equivalent standard method concentration by efficacy in ug/mL).

The VITEK® 2 AST-Gram Positive Lefamulin (≤ 0.03 - ≥4 µg/mL) device is an antimicrobial susceptibility testing system designed for Gram-positive microorganisms. The acceptance criteria and performance of the device are detailed below.

1. Table of Acceptance Criteria and Reported Device Performance

2. Sample size used for the test set and the data provenance

The test set included:

• 404 isolates for Essential Agreement reporting and 404 isolates for Category Agreement reporting (derived from the numerators/denominators in Table 2).
• 3 resistant isolates were tested for VME (Very Major Error)
• 401 susceptible isolates were tested for ME (Major Error)

The data provenance is described as an "external evaluation" conducted with "fresh and stock clinical isolates, as well as a set of challenge strains." The document does not specify the country of origin of the data or explicitly state whether the study was retrospective or prospective.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts

This information is not provided in the given text.

4. Adjudication method for the test set

This information is not provided in the given text.

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

A multi-reader multi-case (MRMC) comparative effectiveness study with human readers assisted by AI is not applicable to this device. This device is an automated antimicrobial susceptibility test system, not an AI-assisted diagnostic tool interpreted by human readers.

6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done

Yes, a standalone performance evaluation was done. The VITEK® 2 AST-GP Lefamulin system's performance was compared directly to the CLSI broth microdilution reference method (the ground truth), without human intervention in the interpretation of the VITEK® 2 results. The system automatically generates MIC values and interpretive categories.

7. The type of ground truth used

The ground truth used was the CLSI broth microdilution reference method, incubated at 16-20 hours.

8. The sample size for the training set

The document does not explicitly mention a separate "training set" or its sample size. The description focuses on the external evaluation data used for performance assessment. As an AST system, the device's "training" for MIC determination is inherent in its design based on established microdilution principles and may not involve a distinct, large-scale machine learning training set in the way an AI algorithm might.

9. How the ground truth for the training set was established

Since a distinct training set is not explicitly mentioned as per the prompt's context (e.g., for an AI algorithm), details on how its ground truth was established are not provided. The device's operation is based on established microbiological principles, and its performance is validated against the CLSI broth microdilution reference method.

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VITEK® 2 Streptococcus Penicillin is designed for antimicrobial susceptibility testing of Streptococcus species 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 Streptococcus Penicillin is a quantitative test. Penicillin has been shown to be active against most strains of the microorganisms listed below, according to the FDA label for this antimicrobial.

Active both in vitro and in clinical infections: Beta hemolytic Streptococci groups C and G Streptococcus pyogenes Streptococcus agalactiae Streptococcus viridans group Streptococcus pneumoniae

The VITEK® 2 Streptococcus Susceptibility Card is intended for use with the VITEK® 2 Systems in clinical laboratories as an in vitro test to determine the susceptibility of Sireptococcus pneumoniae, beta-hemolytic Streptococcus, and Viridans Streptococcus to antimicrobial agents when used as instructed.

The principle of the VITEK® 2 AST cards is based on the microdilution minimum inhibitory concentration (MIC) technique reported by MacLowry and Marsh(1) 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 that contains the MIC value along with the interpretive category result for each antibiotic contained on the card.

VITEK® 2 Streptococcus Penicillin has the following concentrations in the card: 0.06, 0.12, 0.5, and 2ug/mL (equivalent standard method concentration by efficacy in ug/mL).

Here's a summary of the acceptance criteria and study details for the VITEK® 2 Streptococcus Penicillin device:

1. Acceptance Criteria and Reported Device Performance

The device performance is compared to the broth microdilution reference method. The key metrics are Essential Agreement (EA) and Category Agreement (CA), along with Very Major Errors (VME), Major Errors (ME), and Minor Errors (mE).

The document states that the device "demonstrated substantially equivalent performance when compared with the 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 August 28, 2009)." This guidance document typically outlines specific numerical acceptance criteria for EA, CA, VME, ME, and mE, which are implicitly met by the reported percentages being considered "acceptable."

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

The sample sizes for the test set are embedded within the "Reported Device Performance" column (e.g., 350 for Streptococcus pneumoniae (non-meningitis), 391 for Streptococcus Viridans group, 833 for Beta-hemolytic Streptococcus).

The data provenance is from "external evaluation... conducted with fresh and stock clinical isolates, as well as a set of challenge strains." This implies a combination of retrospective (stock clinical isolates) and prospective (fresh clinical isolates) data. The country of origin of the data is not specified in the provided text.

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

This information is not provided in the document. The ground truth is established by the CLSI broth microdilution reference method, but details on expert involvement in this process (e.g., reading/interpreting the reference method results) are not mentioned.

4. Adjudication Method for the Test Set

This information is not explicitly provided in the document. The study compares the VITEK® 2 results to the CLSI broth microdilution reference method. Adjudication might be part of the standard CLSI method, but it is not detailed here for discrepancies.

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

No, a multi-reader multi-case (MRMC) comparative effectiveness study was not done. This study focuses on the performance of an automated diagnostic device against a reference method, not on human reader performance with or without AI assistance.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done

Yes, a standalone performance study was done. The VITEK® 2 system is a "Fully Automated Short-Term Incubation Cycle Antimicrobial Susceptibility System," and its performance was evaluated against the CLSI broth microdilution reference method. This is an evaluation of the algorithm's output (MIC values and interpretive categories) without direct human intervention in the interpretation of the VITEK® 2 results.

7. The Type of Ground Truth Used

The type of ground truth used is the broth microdilution reference method, specifically the CLSI method incubated at 16-20 hours. This is typically considered the gold standard for antimicrobial susceptibility testing.

8. The Sample Size for the Training Set

The document does not explicitly state the sample size for the training set. The study describes "external evaluation" for performance, but it doesn't separate out a specific training set size for the VITEK® 2 algorithm itself.

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

The document does not explicitly state how the ground truth for any training set was established, as it primarily focuses on the performance evaluation of the final device against a reference method. However, given that the device is an "Automated quantitative antimicrobial susceptibility test," it's highly probable that any internal training/development would have used an established reference method (like broth microdilution) to establish ground truth for algorithm development.

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VITEK® 2 AST-Gram Positive Daptomycin is designed for antimicrobial susceptibility testing of Gram positive microorganisms and is intended for use with the VITEK® 2 Compact Systems as a laboratory aid in the determination of in vitro susceptibility to antimicrobial agents. VITEK® 2 AST-Gram Positive Daptomycin is a quantitative test. Daptomycin has been shown to be active against most strains of the microorganisms listed below, according to the FDA label for this antimicrobial.

Active both in vitro and in clinical infections: Enterococcus faecalis (vancomycin-susceptible isolates only) Staphylococcus aureus (including methicillin-resistant isolates)

In vitro data are available, but their clinical significance is unknown: Enterococcus faecalis (vancomycin-resistant isolates)

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 S. agalactiae to antimicrobial agents when used as instructed.

The principle of the VITEK® 2 AST cards is based on the microdilution minimum inhibitory concentration (MIC) technique reported by MacLowry and Marsh(1) 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 that contains the MIC value along with the interpretive category result for each antibiotic contained on the card.

VITEK® 2 AST-GP Daptomycin has the following concentrations in the card: 0.5, 1, 2, 4, and 8 ug/mL (equivalent standard method concentration by efficacy in ug/mL).

The provided document describes the VITEK® 2 AST-GP Daptomycin system, an antimicrobial susceptibility test, and its performance evaluation.

Here's an analysis of the acceptance criteria and the study proving the device meets them:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria for antimicrobial susceptibility test (AST) systems in the US are generally defined by the FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems. While specific numerical targets for Essential Agreement (EA) and Category Agreement (CA) are usually outlined in this guidance, the summary states the device demonstrated substantially equivalent performance when compared with the broth microdilution reference method, as defined in the FDA Class II Special Controls Guidance Document.

The reported performance of the VITEK® 2 AST-GP Daptomycin is provided in "Table 2: VITEK® 2 AST-GP Daptomycin Performance".

Note on VME/ME/mE for Staphylococcus aureus: The document lists "N/A" for VME and mE for Staphylococcus aureus and "0.0%" for ME for Enterococcus faecalis. This might indicate that no specific VME/ME/mE were observed or reported in those categories, or that the formatting of the table in the document itself uses N/A for cases where a specific error type threshold wasn't relevant or wasn't met to be explicitly calculated. However, for a complete picture, the FDA guidance document would provide the specific acceptance thresholds for these error types. The (1/8) 12.5% VME for Enterococcus faecalis and (41/270) 15.2% mE for Enterococcus faecalis would likely be subject to specific acceptance criteria limits in the FDA guidance; for example, VMEs are typically expected to be ≤ 1.5% and MEs ≤ 3.0%, while mEs generally have a higher tolerance but still a limit. The document states a 90.5% overall Category Agreement, which for Enterococcus faecalis alone is 84.4%, falling below the typical 90% threshold for CA. This discrepancy might be addressed in a larger context within the full premarket notification, or perhaps the overall performance across all tested species met the required threshold despite one species being lower.

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

• Test Set Sample Size:
  • Staphylococcus aureus: 194 isolates
  • Enterococcus faecalis: 270 isolates
  • Total Clinical Isolates in Performance Study: 194 + 270 = 464 isolates.
  • The study also used a "set of challenge strains" in addition to fresh and stock clinical isolates, but the exact number of challenge strains is not specified in this summary.
• Data Provenance:
  • "An external evaluation was conducted with fresh and stock clinical isolates, as well as a set of challenge strains." This suggests a prospective or a mix of prospective and retrospective collection from external sources (likely clinical laboratories).
  • The document does not specify the country of origin for the data.

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 method is a standardized laboratory procedure, not reliant on human expert interpretation in the same way as, for example, image reading. Therefore, "number of experts" and "qualifications of experts" are not directly applicable in the context of establishing ground truth for this type of antimicrobial susceptibility testing.

4. Adjudication Method for the Test Set

• The reference method itself (CLSI broth microdilution) serves as the "ground truth" or "adjudication." No separate human adjudication process (e.g., 2+1, 3+1 consensus) is applicable or mentioned for this type of in vitro diagnostic device study. The device's results are directly compared to the results of the reference method.

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, a multi-reader multi-case (MRMC) comparative effectiveness study was not done. This type of study design is typically used for AI-powered diagnostic imaging devices where human readers interpret images with or without AI assistance. This device is an automated in vitro diagnostic system for antimicrobial susceptibility testing, not requiring human interpretation of complex visual data for its primary function.

6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done

• Yes, the performance study effectively evaluates the "standalone" performance of the VITEK® 2 AST-GP Daptomycin system. The system automatically processes the samples and generates MIC values and interpretive categories, which are then compared directly to the CLSI broth microdilution reference method. There is no human intervention in the device's determination of susceptibility.

7. The Type of Ground Truth Used

• The ground truth used was the CLSI broth microdilution reference method, which is a highly standardized and accepted laboratory method for determining antimicrobial susceptibility. This is essentially a "gold standard" laboratory method.

8. The Sample Size for the Training Set

• The document does not provide information on the training set size. This type of premarket notification summary focuses on the performance evaluation of the final device, not typically on the specific dataset used for algorithm development or training. The "Discriminant Analysis" mentioned under "Analysis Algorithms" implies a statistical model was used, which would have been developed/trained on a dataset, but details of this dataset are not included in this summary.

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

• As the training set details are not provided, the method for establishing its ground truth is also not described in this summary. It would logically be established using a similar or identical reference method to the test set, but this is not confirmed.

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VITEK® 2 AST-Gram Negative Levolloxacin is designed for antimicrobial susceptibility testing of Gram-negative bacilli and is intended for use with the VITEK® 2 and VITEK® 2 Compact Systems as a laboratory aid in the determination of in vito susceptibility to antimicrobial agents. VITEK® 2 AST-Gram Negative Levofloxacin is a quantitative test. Levolloxacin has been shown to be active against most strains of the microorganisms listed below, according to the FDA label for this antimicrobial.

Active in vitro and in clinical infections: Enterchacter cloacae, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Serratia marcescens

Active in vitro but clinical significance unknown: Citrobacter freundii, Enterobacter aerogenes, Klebsiella oxytoca, Morganii, Pantoea agglomerans, Proteus vulgaris, Providencia rettgeri, Providencia stuartii

VITEK® 2 AST-Gram Negative Levofloxacin also reports the susceptibility for the following additional organism as listed on the FDA Susceptibility Test Interpretive Criteria website: Salmonella spp.

The VITEK® 2 Gram-Negative Susceptibility Card is intended for use with the VITEK® 2 Systems in clinical laboratories as an in vitro test to determine the susceptibility of clinically significant aerobic Gram-negative bacilli to antimicrobial agents when used as instructed.

The principle of the VITEK® 2 AST cards is based on the microdilution minimum inhibitory concentration (MIC) technique reported by MacLowry and Marsh (1) 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 that contains the MIC value along with the interpretive category result for each antibiotic contained on the card.

VITEK® 2 AST-GN Levofloxacin has the following concentrations in the card: 0.25, 0.5, 2, and 8 (equivalent standard method concentration by efficacy in ug/mL).

Here's a breakdown of the acceptance criteria and the study details for the VITEK® 2 AST-Gram Negative Levofloxacin device, based on the provided FDA 510(k) summary:

1. Acceptance Criteria and Reported Device Performance

The acceptance criteria are implicitly defined by the FDA Class II Special Controls Guidance Document for Antimicrobial Susceptibility Test (AST) Systems. The performance metrics reported are Essential Agreement (EA), Category Agreement (CA), Very Major Errors (VME), Major Errors (ME), and minor Errors (mE). Reproducibility and Quality Control also demonstrated acceptable results, although specific percentage thresholds for these are not provided in this summary.

Here's the table of reported device performance:

Notes on Interpretation from the document:

• VITEK 2 Levofloxacin MIC values for Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa tended to be in exact agreement or at least one doubling dilution higher when compared to the reference agar dilution method.
• VITEK 2 Levofloxacin MIC values for Serratia marcescens tended to be in exact agreement or at least one doubling dilution lower when compared to the reference agar dilution method.

2. Sample Size and Data Provenance

The sample sizes for the test set are embedded within the performance data (e.g., 346 for Enterobacterales, 225 for Pseudomonas aeruginosa, 48 for Salmonella spp.). These numbers represent the total number of isolates tested for each organism group.

The data provenance is described as an "external evaluation" conducted with "fresh and stock clinical isolates, as well as a set of challenge strains." The document does not specify the country of origin, but "external" implies outside of the manufacturer's immediate control. The use of "fresh and stock clinical isolates" indicates a mix of prospective (fresh) and retrospective (stock) data, augmented by specific challenge strains.

3. Number of Experts and Qualifications for Ground Truth

The document does not explicitly state the number of experts used or their specific qualifications (e.g., "radiologist with 10 years of experience"). However, the ground truth is established by the "CLSI agar dilution reference method incubated between 16-20 hours." This method is a standardized laboratory procedure, and implicitly requires trained laboratory professionals to perform and interpret, but it's not based on expert consensus in the typical sense of diagnostic imaging or clinical interpretation.

4. Adjudication Method

The concept of "adjudication" in the sense of multiple experts reviewing and reaching a consensus on a case (like 2+1 or 3+1) is not applicable here. The ground truth is determined by a single, standardized reference laboratory method (CLSI agar dilution). Any discrepancies would be between the VITEK 2 device's result and this reference method, leading to the error rates (VME, ME, mE) reported.

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

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not conducted as described. This type of study typically involves human readers or clinicians making diagnoses with and without AI assistance to measure improvement in human performance. The VITEK 2 device is a fully automated laboratory device, and the study compares its performance directly against a reference laboratory method, not against human interpretation of the images/data it produces.

6. Standalone Performance Study

Yes, a standalone (algorithm only without human-in-the-loop performance) study was done. The entire performance evaluation reported in the 510(k) summary is of the VITEK 2 device's output (MIC values and interpretive categories) compared directly to the CLSI agar dilution reference method. The device is intended to be automated, and its performance is assessed independently.

7. Type of Ground Truth Used

The ground truth used is the CLSI agar dilution reference method results. This is a recognized standard laboratory method for determining antimicrobial susceptibility, considered the gold standard for this type of in vitro diagnostic test. It is not based on expert consensus, pathology, or outcomes data in the usual clinical sense, but rather a robust, objective laboratory measurement.

8. Sample Size for the Training Set

The document does not specify the sample size for the training set. It describes the data used for the "external evaluation" (test set) but provides no information about the isolates used to develop or train the VITEK® 2 AST-GN Levofloxacin system's algorithms (Discriminant Analysis).

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

The document does not provide details on how the ground truth for the training set was established. However, given the nature of AST systems, it is highly probable that the training set's ground truth would have also been established using a similar, if not identical, reference method like the CLSI agar dilution method. The device's "Discriminant Analysis" algorithms would have been developed and optimized to correlate its readings with these reference standard results.

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VITEK® 2 AST-Gram Negative Plazomicin is designed for antimicrobial susceptibility testing of Gram negative bacilli 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 AST-Gram Negative Plazomicin is a quantitative test. Plazomicin has been shown to be active against most strains of the microorganisms listed below, according to the FDA label for this antimicrobial.

Active both in vitro and in clinical infections: Escherichia coli Klebsiella pneumoniae Enterobacter cloacae

In vitro data are available, but their clinical significance is unknown:

Citrobacter freundii Citrobacter koseri Klebsiella (Enterobacter) aerogenes Klebsiella oxytoca Proteus vulgaris Serratia marcescens

The VITEK® 2 Gram-Negative Susceptibility Card is intended for use with the VITEK® 2 Systems in clinical laboratories as an in vitro test to determine the susceptibility of clinicaly significant aerobic bacilli to antimicrobial agents when used as instructed.

The principle of the VITEK® 2 AST cards is based on the microdilution minimum inhibitory concentration (MIC) technique reported by MacLowry and Marsh(4) 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 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 that contains the MIC value along with the interpretive category result for each antibiotic contained on the card.

This document, K223478, describes the premarket notification for the VITEK® 2 AST-GN Plazomicin antimicrobial susceptibility testing system. The device is intended to determine the in vitro susceptibility of Gram-negative bacilli to Plazomicin.

Here's an analysis of the acceptance criteria and the study proving the device meets them:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria for antimicrobial susceptibility testing (AST) devices are typically based on Essential Agreement (EA) and Category Agreement (CA), along with limits for Very Major Errors (VME), Major Errors (ME), and Minor Errors (mE), as defined by the FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems. While the document doesn't explicitly state numerical acceptance criteria for each error type (e.g., "VME must be <X%"), it presents the achieved performance.

The reported device performance for Plazomicin testing against Enterobacteriaceae is as follows:

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

• Sample Size for Test Set: The number of isolates tested for performance evaluation against the "FDA (CLSI)" breakpoint (which signifies the primary clinical evaluation) was 858 isolates. Additionally, reproducibility was tested, but the sample size for that specific test is not explicitly broken down beyond the 97.0% result.
• Data Provenance: The study involved an "external evaluation" conducted with "fresh and stock clinical isolates, as well as a set of challenge strains." This suggests a prospective collection of isolates for the study, encompassing both routine clinical samples and specific strains designed to challenge the system. The document does not specify the country of origin of the data.

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

This document describes a diagnostic device that performs Antimicrobial Susceptibility Testing (AST). For AST devices, the "ground truth" is typically established by a reference method, not human experts in the way it would be for imaging interpretation.

• Ground Truth Establishment: The ground truth for the test set was established by the CLSI Broth Microdilution reference method. This is an internationally recognized standard laboratory procedure for determining minimum inhibitory concentrations (MICs) of antimicrobials.
• Number and Qualifications of Experts: There were no human experts establishing the ground truth for this type of test by consensus reading. The ground truth is a laboratory measurement performed according to a standardized protocol.

4. Adjudication Method for the Test Set

Since the ground truth is established by a standardized laboratory reference method (CLSI Broth Microdilution), no adjudication method (like 2+1 or 3+1 consensus) was used or needed in the traditional sense for diagnostic systems relying on human interpretation. The comparison is directly between the device's output and the MIC values from the reference method.

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

No MRMC comparative effectiveness study was mentioned or performed. This device is an automated laboratory instrument for determining antimicrobial susceptibility, not an imaging AI tool designed to assist human readers. Therefore, the concept of human readers improving with AI assistance is not applicable here.

6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study

Yes, a standalone performance study was conducted. The VITEK® 2 AST-GN Plazomicin system, including its "Growth Pattern Analysis (GPA)" algorithms, performs the susceptibility testing automatically. The performance metrics (Essential Agreement, Category Agreement, and Error Rates) presented in Table 2 are the direct output of the device compared to the reference method, without human intervention in the interpretation of the VITEK 2 results themselves.

7. Type of Ground Truth Used

The type of ground truth used was an established laboratory reference method: the CLSI Broth Microdilution method. This method provides quantitative Minimum Inhibitory Concentration (MIC) values, which are then categorized (Susceptible, Intermediate, Resistant) based on breakpoints.

8. Sample Size for the Training Set

The document does not provide information on the sample size for a training set. For AST devices, the "training" of the algorithm typically involves a robust development process using a large library of characterized isolates to optimize the growth pattern analysis (GPA) algorithms to accurately predict MICs. This development phase is usually distinct from the clinical validation study described here. The 858 isolates represent the test set for performance validation.

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

The document does not describe how the ground truth for the training set (if a distinct one was used for specific algorithm development) was established. However, it's highly probable that similar to the test set, the ground truth for any algorithm development or "training" would also rely on established reference methods like CLSI Broth Microdilution to characterize the isolates used in that phase.

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VITEK® 2 AST-Gram Negative Cefazolin is designed for antimicrobial susceptibility testing of Gram negative bacilli 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 AST-Gram Negative Cefazolin is a quantitative test. Cefazolin has been shown to be active against most strains of the microorganisms listed below, according to the FDA label for this antimicrobial.

Active in vitro and in clinical infections: Escherichia coli Proteus mirabilis

The VITEK® 2 Gram-Negative Susceptibility Card is intended for use with the VITEK® 2 Systems in clinical laboratories as an in vitro test to determine the susceptibility of clinically significant aerobic Gram-negative bacilli to antimicrobial agents when used as instructed.

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(0). 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 that contains the MIC value along with the interpretive category result for each antibiotic contained on the card.

VITEK® 2 AST-GN Cefazolin (≤1 - ≥32 µg/mL) has the following concentrations in the card: 1, 2, and 8 ug/mL (equivalent standard method concentration by efficacy in ug/mL).

The provided text describes the performance study for the VITEK® 2 AST-Gram Negative Cefazolin (≤1 - ≥32 µg/mL) device, which is an antimicrobial susceptibility testing system.

Here's a breakdown of the requested information:

1. Table of Acceptance Criteria and Reported Device Performance:

The acceptance criteria for AST systems are defined in the FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA (Issued August 28, 2009). While the specific numerical thresholds for acceptance are not explicitly listed in this document extract, the performance data provided is presented against these guidelines.

Note: The "N/A" for VME, ME, and mE under Essential Agreement indicates that these specific error types are separately reported under Category Agreement in the provided table, which is a common practice for AST system performance reporting.

2. Sample Size and Data Provenance:

• Test Set Sample Size: Not explicitly stated as a single number. The study mentions "fresh and stock clinical isolates, as well as a set of challenge strains." The quantitative performance metrics (EA, CA, Reproducibility) are derived from this test set.
• Data Provenance: The document does not specify the country of origin of the data. It indicates the study was an "external evaluation." It is implied to be prospective as it involves testing isolates with the VITEK® 2 AST-GN Cefazolin device and comparing it to a reference method.

3. Number of Experts and Qualifications:

Not applicable. This study evaluated an automated antimicrobial susceptibility test system (VITEK® 2) against a recognized reference method (CLSI broth microdilution). It did not involve human experts establishing ground truth through image interpretation or similar processes common in AI/Imaging studies.

4. Adjudication Method for the Test Set:

Not applicable. Ground truth for antimicrobial susceptibility testing is established by a standardized laboratory reference method (CLSI broth microdilution), not by consensus among human experts.

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

No, an MRMC comparative effectiveness study was not done. This type of study is typically performed for AI systems that assist human readers in tasks like image interpretation. The VITEK® 2 system is an automated diagnostic device; its performance is compared to a laboratory reference standard, not to human readers' performance with and without AI assistance.

6. Standalone Performance:

Yes, a standalone performance evaluation was done. The reported performance metrics (Essential Agreement, Category Agreement, Reproducibility) represent the performance of the VITEK® 2 AST-GN Cefazolin system (algorithm only, as it's an automated test) compared to the CLSI broth microdilution reference method.

7. Type of Ground Truth Used:

The type of ground truth used was CLSI broth microdilution reference method, incubated at 16-24 hours. This is a widely accepted laboratory standard for determining antimicrobial susceptibility.

8. Sample Size for the Training Set:

Not applicable or not explicitly mentioned as a "training set" in the context of machine learning. This device is described as operating based on "microdilution minimum inhibitory concentration (MIC) technique," which suggests a deterministic algorithm rather than a machine learning model that undergoes "training." The system's rules or parameters would be pre-defined based on established microbiological principles, not trained on a large dataset in the way a deep learning model would be.

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

Not applicable for the reasons mentioned above (not a machine learning model with a distinct training phase requiring ground truth establishment from raw data). The "ground truth" equivalent for developing such a system would involve extensive research and validation against established microbiological methods like the CLSI broth microdilution method during its initial development and calibration.

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VITEK® 2 Streptococcus Tetracycline is designed for antimicrobial susceptibility testing of Streptococcus species 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 Streptococcus Tetracycline is a quantitative test. Tetracycline has been shown to be active against the microorganisms listed below, according to the FDA label for this antimicrobial.

Active in vitro and in clinical infections: Streptococcus pneumoniae Streptococcus pyogenes*

*The VITEK® 2 Streptococcus Susceptibility Card also reports the susceptibility of the following additional organisms as listed on the FDA Susceptibility Test Interpretative Criteria website (STIC): Streptococcus spp. B-Hemolytic Group (other than S. pyogenes).

The VITEK® 2 Streptococcus Susceptibility Card is intended for use with the VITEK® 2 Systems in clinical laboratories as an in vitro test to determine the susceptibility of Streptococcus pneumoniae, beta-hemolytic Streptococcus, and Viridans Streptococcus to antimicrobial agents when used as instructed.

The principle of the VITEK® 2 AST cards is based on the microdilution minimum inhibitory concentration (MIC) technique reported by MacLowry and Marsh(1) 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 that contains the MIC value along with the interpretive category result for each antibiotic contained on the card.

VITEK® 2 Streptococcus Tetracycline has the following concentrations in the card: 0.125, 0.5, 1, and 4 ug/mL (equivalent standard method concentration by efficacy in ug/mL).

Here's an analysis of the acceptance criteria and study proving the device meets those criteria, based on the provided text:

Device: VITEK® 2 Streptococcus Tetracycline (≤0.25 - ≥16 µg/mL)
Intended Use: Antimicrobial susceptibility testing of Streptococcus species, as a laboratory aid in determining in vitro susceptibility to antimicrobial agents. Specifically for Streptococcus pneumoniae and Streptococcus pyogenes, with additional reporting for Beta-hemolytic Streptococcus (other than S. pyogenes).

Acceptance Criteria and Reported Device Performance

The study compared the VITEK® 2 Streptococcus Tetracycline performance against the CLSI broth microdilution reference method. The acceptance criteria are implicitly defined by the guidance document cited: "FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA (Issued August 28, 2009)."

Note on N/A for VME/ME: The table explicitly states "N/A" for VME and ME for S. pneumoniae and S. pyogenes. This often happens when there are no resistant isolates in the sample set or too few to reliably calculate these error rates, or if the "N/A" rather indicates that essential and categorical agreements are sufficient and the specific error rates are not the primary metrics for that specific organism set. However, for Beta-hemolytic Streptococcus, VME, ME, and mE percentages are provided, suggesting these metrics were relevant for that group.

Study Details

1. Sample sizes used for the test set and the data provenance:

   • Test Set Sample Sizes:
     • Streptococcus pneumoniae: 289 isolates
     • Streptococcus pyogenes: 308 isolates
     • Beta-hemolytic Streptococcus (other than S. pyogenes): 530 isolates
   • Total Isolates: 289 + 308 + 530 = 1127 isolates
   • Data Provenance: The study involved an "external evaluation" conducted with "fresh and stock clinical isolates, as well as a set of challenge strains." The document does not specify the country of origin of the data or whether the study was retrospective or prospective. Typically, clinical isolates imply prospective collection from various clinical labs in the country where the study was primarily conducted (likely the US, given FDA submission).

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

   • Not applicable in this context. The ground truth for antimicrobial susceptibility testing (AST) is established by a standardized, physical reference method, not by expert consensus on interpretations of images or signals. The reference method used was the CLSI broth microdilution reference method.

3. Adjudication method for the test set:

   • Not applicable. As the ground truth is established by a standardized laboratory method (broth microdilution), there's no need for human adjudication of results in the traditional sense. The comparison is between the device's output and the reference method's output.

4. 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:

   • Not applicable. This is not an AI/imaging device. It's an automated antimicrobial susceptibility testing system. The "readers" are the instruments (VITEK® 2 and VITEK® 2 Compact Systems) which produce quantitative results (MIC) and interpretive categories (Susceptible, Intermediate, Resistant).

5. If a standalone (i.e. algorithm only without human-in-the loop performance) was done:

   • Yes, the performance listed in Table 2 (Essential Agreement and Category Agreement) represents the standalone performance of the VITEK® 2 system compared to the reference method. The device is designed to provide automated results.

6. The type of ground truth used:

   • Reference Method: The ground truth was established using the CLSI broth microdilution reference method, incubated at 16-24 hrs. This is a well-established and standardized laboratory method for determining minimum inhibitory concentrations (MICs) of antimicrobials.

7. The sample size for the training set:

   • The document implies that the study described is a validation study used to support regulatory submission, not a study that involved a training phase for a machine learning model. Therefore, a "training set" in the context of AI is not relevant here. The device uses "Discriminant Analysis" algorithms, which would have been developed and validated internally during the device's original development, not as part of this specific 510(k) submission. No training set size is provided for the algorithms themselves.

8. How the ground truth for the training set was established:

   • Not applicable, as this is not an AI/ML development study presented in the document. The "ground truth" for developing the underlying discriminant analysis algorithms (mentioned as the "Analysis Algorithms") would have traditionally been established using similar reference methods during the initial R&D phase of the VITEK® 2 system itself.

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