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ETEST® is a manual, quantitative technique for the determination of antimicrobial susceptibility of non‑fastidious Gram‑negative and Gram‑positive aerobic bacteria and fastidious bacteria. The system comprises a predefined antibiotic gradient which is used to determine the Minimum Inhibitory Concentration (MIC, in μg/mL) of different antimicrobial agents against microorganisms tested on agar media after overnight incubation.

Testing with ETEST® Aztreonam/Avibactam (AZA) (0.016/4-256/4 μg/mL) is indicated for Enterobacterales, as recognized by the FDA Susceptibility Test Interpretive Criteria (STIC).

The ETEST® Aztreonam/Avibactam (AZA) (0.016/4-256/4 μg/mL) demonstrated acceptable performance with the following microorganisms:

• Enterobacterales:

• Escherichia coli
• Klebsiella pneumoniae
• Klebsiella aerogenes
• Citrobacter freundii complex
• Citrobacter koseri
• Enterobacter cloacae complex
• Proteus mirabilis
• Proteus vulgaris
• Morganella morganii
• Providencia stuartii
• Serratia marcescens

ETEST® is a thin, inert and non-porous plastic strip carrying the MIC reading scale in μg/mL on one side and a predefined antibiotic gradient on the other side.

When the strip is applied to an inoculated agar surface, the preformed antibiotic gradient immediately transfers into the agar matrix, then forming a stable, continuous and exponential gradient of antibiotic concentrations directly underneath the strip. Bacterial growth becomes visible during incubation, and a symmetrical inhibition ellipse centered along the strip appears. The MIC value is read from the scale in terms of μg/mL at complete inhibition of bacterial growth, where the pointed end of the ellipse intersects the strip.

ETEST® Aztreonam/Avibactam (AZA) (0.016/4-256/4 µg/mL) contains a range of Aztreonam from (0.016-256 µg/mL), overlaid with a fixed concentration of 4 µg/mL of Avibactam.

The provided FDA 510(k) clearance letter describes the acceptance criteria and the study proving the ETEST Aztreonam/Avibactam (AZA) device meets these criteria for determining antimicrobial susceptibility.

Here's a breakdown of the requested information:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria for antimicrobial susceptibility test (AST) systems, as outlined by the FDA and CLSI (Clinical and Laboratory Standards Institute), are primarily based on Essential Agreement (EA) and Category Agreement (CA) with a reference method.

The acceptance criteria are implicitly met if the reported performance metrics achieve or exceed the established thresholds (though the exact numerical acceptance thresholds for EA and CA are not explicitly stated as "acceptance criteria" values in this document, standard FDA guidance for AST devices typically requires EA ≥ 90% and CA ≥ 90% for overall performance).

Note: The document also states that the device "demonstrated substantially equivalent performance when compared with the CLSI M07-11th Ed (January 2018) broth microdilution reference method, following rules as defined in the FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems; Guidance for Industry and FDA, issued on August 28, 2009 and following specifications as defined in CLSI M100 35th Ed. (January 2025)." This indicates adherence to established regulatory and standard-setting body guidelines for performance.

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

• Sample Size for Test Set: A total of 602 strains of Enterobacterales were used for the performance evaluation.
  • This included:
    • Escherichia coli (150 strains)
    • Klebsiella pneumoniae (118 strains)
    • Enterobacter cloacae complex (67 strains, including E. cloacae, E. hormaechei, E. asburiae, E. roggenkampii, E. ludwigii)
    • Citrobacter freundii complex (50 strains, including C. freundii, C. braakii, C. murliniae, C. portucalensis)
    • Citrobacter koseri (30 strains)
    • Klebsiella aerogenes (32 strains)
    • Morganella morganii (30 strains)
    • Proteus mirabilis (32 strains)
    • Providencia stuartii (30 strains)
    • Proteus vulgaris (30 strains)
    • Serratia marcescens (33 strains)
  • Additionally, 12 Enterobacterales resistant isolates with high MIC values (≥ 16 µg/mL) were specifically included: Klebsiella pneumoniae (2), Escherichia coli (8), Serratia marcescens (1) and Enterobacter cloacae complex (1).
• Data Provenance: The document states "External evaluations were conducted with fresh and stock clinical isolates, as well as a set of challenge strains." This implies a mix of retrospective (stock clinical isolates, challenge strains) and prospective (fresh clinical isolates) data. The country of origin of the data is not specified in this document.

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

This document describes the validation of an in vitro diagnostic device for antimicrobial susceptibility testing, not an imaging AI device requiring expert human reads. Therefore, the concept of "experts" to establish ground truth in the context of human readers is not directly applicable.

Instead, the ground truth was established by a reference method: the CLSI (Clinical and Laboratory Standards Institute) M07-11th Ed (January 2018) broth microdilution reference method. This method is considered the gold standard for determining Minimum Inhibitory Concentrations (MICs) in microbiology. The qualifications of personnel performing this reference method would be standard microbiology laboratory technicians or scientists trained in CLSI methods, rather than clinical experts like radiologists. The number of individuals/laboratories involved in performing the reference method is not specified.

4. Adjudication Method for the Test Set

Not applicable in the context of in vitro diagnostic device validation using a reference laboratory method. Adjudication methods (like 2+1 or 3+1) are typically used in clinical studies where human readers provide subjective interpretations, and conflicts need resolution. Here, the ground truth is a quantitative, standardized microbiology assay.

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

Not applicable. This is an in vitro diagnostic device (a test strip) for determining antimicrobial susceptibility, not an AI-assisted diagnostic tool for human image interpretation. Therefore, no MRMC study or assessment of human reader improvement with AI assistance was conducted.

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

The device itself is a manual, quantitative technique. It is a physical strip that produces a visual inhibition zone from which a Bacterial MIC value is read. It does not involve a software algorithm in the way an AI diagnostic tool would. Therefore, the concept of "standalone performance" of an "algorithm" is not directly applicable in the same sense as for an AI product.

The performance evaluation (which can be considered analogous to "standalone performance" in that it assesses the device's accuracy without a human "interpretation" component beyond reading the scale) was done by comparing the ETEST Aztreonam/Avibactam (AZA) strip's results to the CLSI broth microdilution reference method. This demonstrates the device's inherent capability to accurately determine MIC values.

7. The Type of Ground Truth Used

The ground truth used was the CLSI M07-11th Ed (January 2018) broth microdilution reference method. This is a highly standardized and accepted laboratory reference method for determining the Minimum Inhibitory Concentration (MIC) of an antimicrobial agent against a microorganism. It serves as the definitive 'truth' against which the performance of the ETEST device is measured.

8. The Sample Size for the Training Set

The document does not explicitly mention a "training set" in the context of machine learning model development. This is an in vitro diagnostic device, not a software algorithm that undergoes a distinct training phase. The development of such devices typically involves extensive R&D, formulation optimization, and internal testing before external clinical evaluations. The "training" in this context would refer to the development and optimization of the test strip's chemical gradient to accurately reflect MIC values, rather than training a data-driven model. The document focuses on the validation (test set) for regulatory clearance.

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

As noted above, the concept of a "training set" and associated ground truth establishment methods for it, as typically applied to machine learning, is not directly relevant to this type of in vitro diagnostic device. The 'ground truth' for validating the performance of this device is consistently the CLSI broth microdilution reference method, which is the gold standard for antimicrobial susceptibility testing. Any internal development or optimization of the ETEST strip formulation would also rely on this or similar established reference methods to guide product development.

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ETEST® is a manual, quantitative technique for the determination of antimicrobial susceptibility of non-fastidious Gram-negative and Gram-positive aerobic bacteria. The system comprises a predefined antibiotic gradient which is used to determine the Minimum Inhibitory Concentration (MIC, in µg/mL) of different antimicrobial agents against microorganisms tested on agar media after overnight incubation.

Sulbactam/Durlobactam has been shown to be active against the Gram-negative aerobic microorganisms listed below according to the FDA label for this antimicrobial agent.

ETEST® SUD can be used to determine the MIC of Sulbactam/Durlobactam against the following microorganisms:

• Acinetobacter baumannii-calcoaceticus complex

ETEST® is a thin, inert and non-porous plastic strip carrying the MIC reading scale in us/mL on one side and a predefined antibiotic gradient on the other side.

When the strip is applied to an inoculated agar surface, the preformed antibiotic gradient immediately transfers into the agar matrix, then forming a stable, continuous and exponential gradient of antibiotic concentrations directly underneath the strip. Bacterial growth becomes visible during incubation, and a symmetrical inhibition ellipse centered along the strip appears. The MIC value is read from the scale in terms of ug/mL at complete inhibition of bacterial growth, where the pointed end of the ellipse intersects the strip.

ETEST® Sulbactam/Durlobactam contains a range of Sulbactam from 0.004 to 64 µg/mL, overlaid with a fixed concentration of 4 µg/mL of Durlobactam.

Here's a breakdown of the acceptance criteria and study details for the ETEST® Sulbactam/Durlobactam (SUD) device, based on the provided FDA 510(k) summary:

Acceptance Criteria and Reported Device Performance

Note: The document states that ETEST® Sulbactam/Durlobactam (SUD) demonstrated substantially equivalent performance compared with the CLSI M07-11th Ed (January 2018) broth microdilution reference method, following rules from the FDA Class II Special Controls Guidance Document and specifications in CLSI M100 330 (March 2023).

Study Details

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

   • Sample Size (Test Set): 562 strains of Acinetobacter baumannii-calcoaceticus complex.
   • Data Provenance: The document states "External evaluations were conducted with fresh and stock clinical isolates, as well as a set of challenge strains." This suggests a combination of retrospective (stock clinical isolates) and potentially prospective (fresh clinical isolates) data. The country of origin is not explicitly mentioned but is likely multi-site given the nature of such evaluations for regulatory clearance.

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

   • The document implies that the CLSI broth microdilution reference method was used as the ground truth. This method is a standardized laboratory procedure and does not typically involve "experts" in the sense of human readers adjudicating images or cases. Instead, it relies on precise technical execution and interpretation according to established CLSI guidelines. Therefore, the concept of a number of experts and their qualifications doesn't directly apply in the same way it would for imaging diagnostics. The "experts" in this context would be the technicians performing the reference method and interpreting the results according to CLSI standards.

3. Adjudication Method for the Test Set:

   • Not applicable as the ground truth is established by a standardized laboratory reference method (CLSI broth microdilution), not human adjudication. The performance metrics (EA, CA) are calculated by comparing the device's MIC values to those obtained from the reference method.

4. 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 primarily relevant for diagnostic devices where human readers interpret results, and the study would assess how AI assistance impacts their performance. For antimicrobial susceptibility testing (AST) devices like ETEST®, the comparison is between the automated/manual device and a standardized reference method.

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

   • Yes, the performance characteristics (Essential Agreement and Category Agreement) are presented for the ETEST® device in standalone mode, comparing its results directly to the CLSI broth microdilution reference method. While ETEST® is a manual technique, its performance evaluation is based on its ability to produce MIC values that align with the reference method. The note about "swabs were used for plate inoculation/streaking and forceps were used for ETEST® strip application" and that "Testing with the optional Inoculator RETRO C80™, Vacuum Pen NEMA C88™, and Applicator SIMPLEX C76™ was not evaluated" confirms that the reported performance reflects the manual ETEST® process itself, without additional automated assistance that might change interpretation.

6. The Type of Ground Truth Used:

   • Standardized Laboratory Reference Method: The ground truth was established using the CLSI M07-11th Ed (January 2018) broth microdilution reference method. This is considered the gold standard for antimicrobial susceptibility testing.

7. The Sample Size for the Training Set:

   • The document does not explicitly state the sample size for a "training set." For an AST device like ETEST®, "training" would typically refer to the development and internal validation phases before external clinical evaluations. The information provided focuses on the performance evaluation using the specified test set.

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

   • As no specific "training set" is detailed in this regulatory summary, the method for establishing ground truth for such a set is not provided. However, it can be inferred that any internal development or validation would also rely on comparisons to established reference methods (like CLSI broth microdilution) for consistency.

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VIDAS® NEPHROCHECK® is an automated test for use on the VIDAS® 3 instrument for the immunoenzymatic quantitative determination of TIMP-2 (Tissue Inhibitor of Metalloproteinase-2) and IGFBP-7 (Insulin-like Growth Factor-Binding Protein 7) proteins in human urine using the ELFA technique (Enzyme Linked Fluorescent Assay) for calculation of the AKIRISKTM Score.

The VIDAS® NEPHROCHECK® assay is intended to be used in conjunction with clinical evaluation in patients who currently have or have had within the past 24 hours acute cardiovascular and or respiratory compromise and are ICU patients as an aid in the risk assessment for moderate or severe acute kidney injury (AKI) within 12 hours of patient assessment. The VIDAS® NEPHROCHECK® test is intended to be used in patients 21 years of age or older.

Each VIDAS® NEPHROCHECK® kit contains: x60 NEPH Reagent Strips, x60 NEPH Solid Phase Receptacles (SPR), 1 NEPH control and 1 NEPH calibrator. The VIDAS® NEPHROCHECK® principle combines an enzyme immunoassay competition method with a final fluorescent detection (ELFA).

The Solid Phase Receptacle (SPR®) serves as the solid phase as well as the pipetting device for the assay. The interior of the NEPH SPR is coated with mouse monoclonal lgG anti-IGFBP-7 andanti-TIMP-2.

The Reagent Strips consist of 10 wells covered with a labeled foil seal. Well 1 is designated for the sample. Six of the wells contain conjugate, wash buffers and substrate. Last well contains the fluorescence substrate.

All of the assay steps are performed automatically by the instrument.

Two detection steps, one for each protein, are performed successively in Well 10.

· The first step is a classical detection step with measurement of the substrate background and incubation of the substrate in the bottom of the SPR®, to generate the first fluorescent signal, which is specific for the IGFBP-7 protein.

· Before the second detection step, the antibodies and proteins in the bottom of the SPR® are removed using the cleaning solution contained in Well 5. The previously used substrate in Well 10 is removed and replaced by fresh substrate contained in Well 9. A new substrate background is then measured, and the substrate is incubated in the top of the SPR® to generate the second fluorescent signal, which is specific for the TIMP-2 protein.

For each protein, the intensity of the fluorescence is proportional to its concentration in the sample. At the end of the test, the protein concentrations are calculated by the instrument in relation to the two calibration curves, one corresponding to each protein, and encoded in the MLE data.

The instrument calculates the AKIRISK™ Score, which is defined as the product of the concentrations of the two proteins, expressed in ng/mL, divided by 1000:

AKIRISK™ Score = ([TIMP-2] x [IGFBP-7]) / 1000

The result of the VIDAS® NEPHROCHECK® assay is reported as the AKIRISK™ Score.

Here's a breakdown of the acceptance criteria and study information for the VIDAS® NEPHROCHECK® device, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance:

The document doesn't explicitly state "acceptance criteria" in a separate section with pass/fail thresholds for a primary clinical endpoint. Instead, it presents various analytical and clinical performance characteristics. The clinical performance is compared implicitly to the predicate device to establish substantial equivalence.

Here's an interpretation of relevant performance characteristics reported:

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VITEK® 2 AST-Gram Positive Linezolid 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 Linezolid is a quantitative test. Linezolid 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:

Enterococcus faecium (vancomycin-resistant isolates only) Staphylococcus aureus (including methicillin-resistant isolates) Streptococcus agalactiae

In vitro data are available, but clinical significance is unknown: Enterococcus faecalis (including vancomycin-resistant isolates) Enterococcus faecium (vancomycin-susceptible isolates) Staphylococcus epidermidis (including methicillin-resistant isolates) Staphylococcus haemolyticus

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 Linezolid has the following concentrations in the card: 0.5, 1, and 2 ug/mL (equivalent standard method concentration by efficacy in us/mL).

Here's an analysis of the provided text, focusing on the acceptance criteria and the study that proves the device meets those criteria:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria for antimicrobial susceptibility test (AST) systems are generally defined by guidance documents such as the "FDA Class II Special Controls Guidance Document: Antimicrobial Susceptibility Test (AST) Systems." While explicit numerical acceptance criteria (e.g., "EA must be > 90%") are not directly stated in the provided text as a separate table, it can be inferred from the "Performance Overview and Conclusion" section and the structure of the performance data presented.

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

• Sample Size:
  • Enterococcus spp.: 403 isolates (for EA and CA analysis).
  • Staphylococcus spp.: 390 isolates (for EA and CA analysis).
  • Streptococcus agalactiae: 64 isolates (for EA and CA analysis).
  • Total isolates for Linezolid across all species shown in the main table: 403 + 390 + 64 = 857 isolates.
  • Staphylococcus haemolyticus (specific note): 35 isolates were used when evaluating performance for this specific species.
• Data Provenance: The study used "fresh and stock clinical isolates, as well as a set of challenge strains." This indicates a mix of retrospective (stock isolates) and potentially prospective (fresh clinical isolates) data. The geographic origin of the data (e.g., country of origin) 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 specified in the provided text. The ground truth was established by the "CLSI agar dilution reference method," which is a laboratory standard rather than a consensus by human experts in the typical sense for imaging or clinical diagnosis. Clinical and Laboratory Standards Institute (CLSI) methods are highly standardized.

4. Adjudication Method for the Test Set

This type of information (e.g., 2+1, 3+1 expert adjudication) is typically relevant to diagnostic devices where human interpretation might be subjective. For an automated antimicrobial susceptibility test system comparing its results to a standardized reference laboratory method (CLSI agar dilution), an adjudication method as commonly understood in medical imaging studies is not applicable or described. The comparison is objective against 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

An MRMC study is not applicable here. This device (VITEK 2 AST-GP Linezolid) is an automated system for antimicrobial susceptibility testing, not an AI-assisted diagnostic tool for human readers. There is no human-in-the-loop component described for its core function that would necessitate such a study.

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 Linezolid system, which is described as an "Automated quantitative antimicrobial susceptibility test," was directly compared to the "CLSI agar dilution reference method." The results presented in Table 2 are the direct output of the VITEK® 2 system. This is a standalone performance evaluation of the device.

7. The Type of Ground Truth Used

The ground truth used was the CLSI agar dilution reference method. This is a validated, standardized laboratory method considered the gold standard for determining minimum inhibitory concentrations (MICs) of antimicrobials.

8. The Sample Size for the Training Set

The provided text describes a "Special 510(k) Submission" for a device that is essentially an updated version of a previously cleared device (K032766) with a change in breakpoints for Staphylococcus species. The study described focuses on validating the performance of this updated device against a reference method.

There is no explicit mention of a separate "training set" size in the context of machine learning or algorithm development. The VITEK® 2 system itself uses "Discriminant Analysis" algorithms, suggesting a historical development and training process, but the current document focuses on the validation of the updated breakpoints rather than the de novo development of the algorithm. If "training set" refers to the data used historically to develop the "Discriminant Analysis" algorithm, that information is not provided.

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

Given that no explicit "training set" is described for this specific submission's validation study, the method for establishing ground truth for a training set (if one was used for the initial development of the VITEK® 2's "Discriminant Analysis" algorithm) is not detailed in the provided text. The current document focuses on comparing the device's output to the CLSI agar dilution reference method for validation.

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ETEST® is a manual, quantitative technique for the determination of antimicrobial susceptibility of non-fastidious Gram-negative and Gram-positive aerobic bacteria. The system comprises a predefined antibiotic gradient which is used to determine the Minimum Inhibitory Concentration (MIC, in ug/mL) of different antimicrobial agents against microorganisms tested on agar media after overnight incubation. Plazomicin has been shown to be active against most isolates of the bacteria listed below according to the FDA label for this antimicrobial agent.

ETEST® PLZ can be used to determine the MIC of Plazomicin aqainst the following microorganisms:

Active both in vitro and in clinical infections:

• Escherichia coli
• Klebsiella pneumoniae
• Proteus mirabilis
• Enterobacter cloacae

In vitro data are available for the following microorganisms, but clinical significance is unknown:

• Citrobacter freundii
• Citrobacter koseri
• Klebsiella (Enterobacter) aerogenes
• Klebsiella oxytoca
• Morganella morganii
• Proteus vulgaris
• Providencia stuartii
• Serratia marcescens

ETEST® is a thin, inert and non-porous plastic strip carrying the MIC reading scale in µg/mL on one side and a predefined antibiotic gradient on the other side.

When the strip is applied to an inoculated agar surface, the preformed antibiotic gradient immediately transfers into the agar matrix, then forming a stable, continuous and exponential gradient of antibiotic concentrations directly underneath the strip. Bacterial growth becomes visible during incubation, and a symmetrical inhibition ellipse centered along the strip appears. The MIC value is read from the scale in terms of ug/mL at complete inhibition of bacterial growth, where the pointed end of the ellipse intersects the strip.

ETEST® Plazomicin contains a range of plazomicin from 0.016 to 256 ug/mL.

Here's a summary of the acceptance criteria and study details for the ETEST® Plazomicin (PLZ) device, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

The device performance is compared to the CLSI M07-A11 broth microdilution reference method. The acceptance criteria are implicitly derived from the CLSI guidance documents and FDA's Class II Special Controls Guidance Document for Antimicrobial Susceptibility Test (AST) Systems.

a) EA = % of MIC values within ± 1 dilution of the reference method.

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

• Test Set Sample Size: The performance data for Enterobacteriaceae included a total of 605 strains.
  • Breakdown by organism: Escherichia coli (78), Klebsiella pneumoniae (89), Proteus mirabilis (63), Enterobacter cloacae (60), Citrobacter freundii (59), Citrobacter koseri (34), Klebsiella (Enterobacter) aerogenes (38), Klebsiella oxytoca (39), Morganella morganii (31), Proteus vulgaris (34), Providencia stuartii (35), and Serratia marcescens (38).
• Data Provenance: "External evaluations were conducted with fresh and stock clinical isolates, as well as a set of challenge strains." This indicates a mix of retrospective (stock clinical isolates) and prospective (fresh clinical isolates) data, along with curated challenge strains. The country of origin is not specified but implicitly involves clinical settings relevant to the device's intended use.

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

Not explicitly stated. The ground truth was established by comparing the ETEST® Plazomicin results with the CLSI broth microdilution reference method. This method itself is the gold standard, and its execution and interpretation typically rely on trained laboratory personnel rather than "experts" in the sense of physicians or radiologists adjudicating images.

4. Adjudication Method for the Test Set

Not applicable in the traditional sense for this type of device. The study design involves direct comparison to a reference method (CLSI broth microdilution) rather than expert adjudication of results. Discrepancies (e.g., categorical errors) are noted and explained.

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

No, an MRMC comparative effectiveness study was not done. This device is an antimicrobial susceptibility test system, not an imaging device requiring human reader interpretation in the same way. The evaluation focuses on the agreement between the test strip and a reference laboratory method.

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

This is a standalone device performance study. The ETEST® strip visually provides the Minimum Inhibitory Concentration (MIC) value, which is then interpreted. While a human reads the result from the strip, the performance study itself assesses the accuracy of the strip's ability to generate that MIC in comparison to a reference method. It's not an "algorithm" in the typical software sense, but the device's inherent functional performance is evaluated independently.

7. The Type of Ground Truth Used

The ground truth used was the CLSI M07-A11 broth microdilution reference method. This is considered the gold standard for determining antimicrobial susceptibility.

8. The Sample Size for the Training Set

The document does not explicitly mention a separate "training set" in the context of device development or algorithm training. The performance study focuses on the evaluation of the finished product using clinical and challenge isolates against a reference method.

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

As no training set is explicitly described for algorithm development, this point is not applicable. The device's underlying mechanism is a physical chemical gradient, not a machine learning algorithm that requires a separate training set. The "development" or "calibration" of the ETEST® strips would involve internal studies to ensure the accuracy of the gradient, likely using similar reference methods.

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