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The GenMark ePlex® Blood Culture Identification Gram-Negative (BCID-GN) Panel is a qualitative nucleic acid multiplex in vitro diagnostic test intended for use on GenMark's ePlex Instrument for simultaneous qualitative detection and identification of multiple potentially pathogenic gram-negative bacterial organisms and select determinants associated with antimicrobial resistance in positive blood culture. In addition, the ePlex BCID-GN Panel is capable of detecting several gram-positive bacteria (Pan Gram-Positive assay) and several Candida species (Pan Candida assay). The ePlex BCID-GN Panel is performed directly on blood culture samples identified as positive by a continuous monitoring blood culture system and which contain gram-negative organism.

The following bacterial organisms and genes associated with antibiotic resistance are identified using the ePlex BCID-GN Panel: Acinetobacter baumannii, Bacteroides fragilis, Citrobacter sakazakii, Enterobacter cloacae complex, Enterobacter (non-cloacae complex), Escherichia coli, Fusobacterium necrophorum, Fusobacterium nucleatum, Haemophilus influenzae, Klebsiella oxytoca, Klebsiella pneumoniae group, Morganii, Neisseria meningitidis, Proteus, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella, Serratia marcescens, Stenotrophomonas maltophilia, CTX-M (blaCTX-M), IMP (blaMP) , KPC (blaKPC) , NDM (blaNDM), OXA (blaOXA) (OXA-23 and OXA-48 groups only), and VIM (blaVIM).

The ePlex BCID-GN Panel contains assays for the detection of genetic determinants associated with resistance to antimicrobial agents including CTX-M(blaCTX-M), which is associated with resistance to extended spectrum betalactamase (ESBL)-mediated resistance to penicillins, cephalosporins, and monobactams, as well as OXA (blaOXA) (OXA-23 and OXA-48 groups only), KPC (blaKPC), and metallo-beta-lactamases IMP (blaIMP), and NDM (blaNDM), which is associated with carbapenemase-mediated resistance. The antimicrobial resistance gene detected may or may not be associated with the agent responsible for disease. Negative results for these select antimicrobial resistance assays do not indicate susceptibility, as there are multiple mechanisms of resistance in gramnegative bacteria.

The ePlex BCID-GN Panel also contains targets designed to detect a broad range of organisms with a potentially misleading Gram stain result or organisms that may be missed by Gram staining altogether, for example in the case of coinfections. These include a broad Pan Gram-Positive assay (which is designed to detect Bacillus cereus group, Bacillus subtilis group, Enterococcus, Staphylococus, and Streptococcus), as well as a Pan Candida assay, which is designed to detect four Candida species: Candida albicans, Candida krusei, and Candida parapsilosis.

The detection and identification of specific bacterial and fungal nucleic acids from individuals exhibiting signs and/or symptoms of bloodstream infection aids in the diagnosis of bloodstream infection when used in conjunction with other clinical information. The results from the ePlex BCID-GN Panel are intended to be interpreted in conjunction with Gram stain results and should not be used as the sole basis for diagnosis, treatment, or other patient management decisions.

Negative results in the setting of a suspected bloodstream infection with pathogens that are not detected by this test. Positive results do not rule out co-infection with other organisms; the organism(s) detected by the ePlex BCID-GN Panel may not be the definite cause of disease. Additional laboratory testing (e.g. sub-culturing of positive blood cultures for identification of organisms not detected by ePlex BCID-GN Panel and for susceptibility testing, differentiation of mixed growth, and association of antimicrobial resistance marker genes to a specific organism) and clinical presentation must be taken into consideration in the final diagnosis of bloodstream infection.

The ePlex Blood Culture Identification Gram-Negative (BCID-GN) Panel is based on the principles of competitive nucleic acid hybridization using a sandwich assay format, wherein a single-stranded target binds concurrently to a sequence-specific solution-phase signal probe and a solid-phase electrode-bound capture probe. The test employs nucleic acid extraction, target amplification via polymerase chain reaction (PCR) or reverse transcription PCR (RT-PCR) and hybridization of target DNA. In the process, the double-stranded PCR amplicons are digested with exonuclease to generate single-stranded DNA suitable for hybridization.

Nucleic acid extraction from biological samples occurs within the cartridge via cell lysis, nucleic acid capture onto magnetic beads, and release for amplification. The nucleic acid extraction is processed through microfluidic liquid handling. Once the nucleic acid targets are captured and inhibitors are washed away, the magnetic particles are delivered to the electrowetting environment on the printed circuit board (PCB) and the targets are eluted from the particles and amplified.

During hybridization, the single-stranded target DNA binds to a complementary, single-stranded capture probe immobilized on the working gold electrode surface. Single-stranded signal probes (labeled with electrochemically active ferrocenes) bind to specific target sequence / region adjacent to the capture probe. Simultaneous hybridization of target to signal probes and capture probe is detected by alternating current voltammetry (ACV). Each working electrode on the array contains specific capture probes, and sequential analysis of each electrode allows detection of multiple analyte targets.

The presented document is a 510(k) summary for the GenMark ePlex Blood Culture Identification Gram-Negative (BCID-GN) Panel, a qualitative nucleic acid multiplex in vitro diagnostic test. The study aims to demonstrate that the updated device (Subject Device) is substantially equivalent to its predicate device (original GenMark ePlex BCID-GN Panel, K182619). The data focuses on analytical and clinical performance.

Here's an analysis based on the provided text, addressing your specific points:

1. A table of acceptance criteria and the reported device performance:

The document doesn't explicitly state a single "acceptance criteria" table with pre-defined thresholds for all metrics (like sensitivity, specificity) against which the reported performance is directly compared in a summary table. However, it implicitly demonstrates acceptance by presenting individual performance metrics (Sensitivity/PPA and Specificity/NPA) for each target organism and resistance gene across different sample types (Prospective, Retrospective, Contrived, and Overall). The consistent high percentages for these metrics indicate that the device met the required performance for regulatory acceptance, even if the precise numerical cut-offs aren't explicitly stated in a singular table for all parameters.

Instead of a single "acceptance criteria" table, the document functions as a detailed report of performance against implicit acceptance criteria for in vitro diagnostic devices, which typically demand high sensitivity and specificity. The data tables already present the "reported device performance."

Example of reported device performance for a few key targets (extracted from Tables 7-34):

(Note: "Overall" for Pan targets combines Prospective, Retrospective, and Retrospective (Non-Intended Use), but excludes Contrived. The overall figures for other targets combine Prospective/Retrospective and Contrived samples as a whole.)

2. Sample sized used for the test set and the data provenance:

• Test Set Sample Size:

  • Clinical Samples: 349 prospective samples (167 fresh, 182 frozen) and 577 retrospective samples. Total clinical samples: 926.
  • Contrived Samples: 777 samples.
  • Additional Retrospective (Non-Intended Use) for Pan targets: 741 samples.
  • Total evaluable samples across studies: 349 (prospective) + 577 (retrospective) + 777 (contrived) + 741 (non-intended use for pan targets) = 2444 samples in total tested across various evaluations. The overall performance tables combine various subsets of these.

• Data Provenance:

  • Country of Origin: Not explicitly stated, but 7 clinical sites were involved in prospective collection (suggests multi-center, likely within the US given FDA submission).
  • Retrospective or Prospective: Both.
    • Prospective: 349 samples collected from June 2014 through July 2016 (frozen) and June through July 2018 (fresh).
    • Retrospective: 577 samples collected.
    • Contrived: Laboratory-generated samples.

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

The document does not explicitly state the "number of experts" or their specific "qualifications" involved in establishing the ground truth. It refers to "standard laboratory procedures for identification of blood culture isolates, including traditional and automated identification methods, MALDI-TOF IVD, and microbiological and biochemical techniques" (Table 4). For antibiotic resistance genes, it uses "analytically validated qPCR amplification assays followed by bi-directional sequencing." This implies laboratory professionals with expertise in microbiology and molecular diagnostics perform these comparator methods, but specific numbers or individual qualifications are not detailed.

4. Adjudication method (e.g. 2+1, 3+1, none) for the test set:

The document does not describe an explicit "adjudication method" involving multiple human readers (e.g., 2+1 or 3+1). The ground truth is established through comparator methods as described above (standard laboratory procedures, PCR/sequencing). Any discrepancies between the device and these comparator methods are analyzed and explained (e.g., the detailed footnotes in the performance tables and the discussion regarding CTX-M false negatives). This is typical for in vitro diagnostic (IVD) device studies, where ground truth is often determined by a reference laboratory standard or follow-up confirmatory testing, rather than human expert consensus on image interpretation.

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, an MRMC comparative effectiveness study was not done. This device is an in vitro diagnostic (IVD) test for direct detection of pathogens and resistance genes from blood cultures, not an "AI-assisted image interpretation" device to be used by human readers. Therefore, the concept of human readers improving with AI assistance is not applicable here.

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

Yes, this study represents a standalone technical performance evaluation of the ePlex BCID-GN Panel device. The device itself performs the detection and identification, and its results are compared directly to the gold standard comparator methods. There is no "human-in-the-loop" performance element in the operation of this specific diagnostic test.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc):

The ground truth was established by a combination of:

• Standard Laboratory Procedures: including traditional and automated identification methods, MALDI-TOF IVD, and microbiological and biochemical techniques for organism identification.
• Molecular Confirmation: Analytically validated PCR assays followed by bi-directional sequencing for specific organism identifications (e.g., Acinetobacter baumannii, Candida parapsilosis) and for all antibiotic resistance genes (qPCR amplification followed by bi-directional sequencing).
• Additional Testing for Discrepancies: Further investigations (e.g., repeat extractions, qPCR testing from isolates, testing with FDA-cleared multiplex assays) were used to resolve discrepancies and confirm the true status of samples, as detailed in the footnotes for several performance tables (e.g., Table 28 for CTX-M).

This ground truth method is based on a hierarchy of established laboratory and molecular techniques rather than human expert consensus on interpretation.

8. The sample size for the training set:

The document does not explicitly mention a "training set" in the context of machine learning, as this is a molecular diagnostic device, not an AI/ML product. However, the development of such a device involves extensive analytical studies related to inclusivity (reactivity), exclusivity (specificity), and limit of detection (LoD), which are analogous to data used in the development or "training" phase.

• Analytical Reactivity (Inclusivity): Evaluated with a panel of 336 strains/isolates.
• Limit of Detection (LoD): Determined using quantified reference strains for each target.
• In silico analysis: Used for predicted reactivity of genus/group assays and resistance markers, involving evaluation of sequence data.

While not a "training set" in the AI sense, these analytical studies inform the design and performance characteristics of the diagnostic assays.

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

As noted above, there isn't a "training set" in the AI/ML sense. For the analytical studies that are foundational to the device's design (e.g., inclusivity, LoD):

• Ground truth for inclusivity (analytical reactivity): Established by using characterized strains/isolates with known identity. The strains' identities are determined by standard microbiological and molecular methods.
• Ground truth for LoD: Established by using quantified reference strains where the concentration (CFU/mL) of the organism is precisely known.
• Ground truth for in silico analysis: Based on existing genetic sequence data and bioinformatic analysis to predict reactivity, relying on established genetic databases and characterizations.

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The GenMark ePlex® Blood Culture Identification Gram-Negative (BCID-GN) Panel is a qualitative nucleic acid multiplex in vitro diagnostic test intended for use on GenMark's ePlex Instrument for simultaneous qualitative detection and identification of multiple potentially pathogenic gram-negative bacterial organisms and select determinants associated with antimicrobial resistance in positive blood culture. In addition, the ePlex BCID-GN Panel is capable of detecting several gram-positive bacteria (Pan Gram-Positive assay) and several Candida species (Pan Candida assay). The ePlex BCID-GN Panel is performed directly on blood culture samples identified as positive by a continuous monitoring blood culture system and which contain gram-negative organism.

The following bacterial organisms and genes associated with antibiotic resistance are identified using the ePlex BCID-GN Panel: Acinetobacter baumannii, Bacteroides fragilis, Citrobacter, Cronobacter sakazakii. Enterobacter cloacae complex, Enterobacter (non-cloacae complex), Escherichia coli, Fusobacterium necrophorum, Fusobacterium nucleatum, Haemophilus influenzae, Klebsiella oxytoca, Klebsiella pneumoniae group, Morganella morganii, Neisseria meningitidis, Proteus, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella, Serratia, Serratia marcescens, Stenotrophomas maltophilia, СТХ-М (blactх-м), IMP (blамм) , КРС (blakec) , NDM (bland), OXA (blaoxa) (OXA-23 and OXA-48 groups only), and VIM (blaviм).

The ePlex BCID-GN Panel contains assays for the detection of genetic determinants associated with resistance to antimicrobial agents including CTX-M(blactx.M), which is associated with resistance to extended spectrum beta-lactamase (ESBL)-mediated resistance to penicillins, cephalosporins and monobactams, as well as OXA (blaoxA) (OXA-23 and OXA-48 groups only), KPC (blakpc), and metallo-beta-lactamases IMP (blavM), VIM (blavM), and NDM (blaNDM), which is associated with carbapenemase-mediated resistance. The antimicrobial resistance gene detected may or may not be associated with the agent responsible for disease. Negative results for these select antimicrobial resistance assays do not indicate susceptibility, as there are multiple mechanisms of resistance in gram-negative bacteria.

The ePlex BCID-GN Panel also contains targets designed to detect a broad range of organisms with a potentially misleading Gram stain result or organisms that may be missed by Gram staining altogether, for example in the case of co-infections. These include a broad Pan Gram-Positive assay (which is designed to detect Bacillus cereus group, Bacillus subtilis group, Enterococcus, Staphylococcus, and Streptococcus), as well as a Pan Candida assay, which is designed to detect four Candida species: Candida albicans, Candida glabrata, Candida krusei, and Candida parapsilosis.

The detection and identification of specific bacterial and fungal nucleic acids from individuals exhibiting signs and/or symptoms of bloodstream infection aids in the diagnosis of bloodstream infection when used in conjunction with other clinical information. The results from the ePlex BCID-GN Panel are intended to be interpreted in conjunction with Gram stain results and should not be used as the sole basis for diagnosis, treatment, or other patient management decisions.

Negative results in the setting of a suspected bloodstream infection may be due to infection with pathogens that are not detected by this test. Positive results do not rule out co-infection with other organisms; the organism(s) detected by the ePlex BCID-GN Panel may not be the definite cause of disease. Additional laboratory testing (e.g. sub-culturing of positive blood cultures for identification of organisms not detected by ePlex BCID-GN Panel and for susceptibility testing, differentiation of mixed growth, and association of antimicrobial resistance marker genes to a specific organism) and clinical presentation must be taken into consideration in the final diagnosis of bloodstream infection.

The ePlex Blood Culture Identification Gram-Negative (BCID-GN) Panel is based on the principles of competitive nucleic acid hybridization using a sandwich assay format, wherein a single-stranded target binds concurrently to a sequence-specific solution-phase signal probe and a solid-phase electrode-bound capture probe. The test employs nucleic acid extraction, target amplification via polymerase chain reaction (PCR) or reverse transcription PCR (RT-PCR) and hybridization of target DNA. In the process, the double-stranded PCR amplicons are digested with exonuclease to generate single-stranded DNA suitable for hybridization.

Nucleic acid extraction from biological samples occurs within the cartridge via cell lysis, nucleic acid capture onto magnetic beads, and release for amplification. The nucleic acid extraction is processed through microfluidic liquid handling. Once the nucleic acid targets are captured and inhibitors are washed away, the magnetic particles are delivered to the electrowetting environment on the printed circuit board (PCB) and the targets are eluted from the particles and amplified.

During hybridization, the single-stranded target DNA binds to a complementary, single-stranded capture probe immobilized on the working gold electrode surface. Single-stranded signal probes (labeled with electrochemically active ferrocenes) bind to specific target sequence / region adjacent to the capture probe. Simultaneous hybridization of target to signal probes and capture probe is detected by alternating current voltammetry (ACV). Each working electrode on the array contains specific capture probes, and sequential analysis of each electrode allows detection of multiple analyte targets.

Here's a summary of the acceptance criteria and study information for the ePlex Blood Culture Identification Gram Negative (BCID-GN) Panel, extracted from the provided text:

Acceptance Criteria and Device Performance for ePlex Blood Culture Identification Gram Negative (BCID-GN) Panel

The ePlex BCID-GN Panel is a qualitative nucleic acid multiplex in vitro diagnostic test for the simultaneous qualitative detection and identification of multiple potentially pathogenic gram-negative bacterial organisms and select determinants associated with antimicrobial resistance in positive blood cultures. Performance characteristics were evaluated through clinical and analytical studies.

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are generally implied by the achieved performance metrics, which show high Positive Percent Agreement (PPA) for sensitivity and Negative Percent Agreement (NPA) for specificity. While explicit numerical acceptance thresholds are not directly stated as "acceptance criteria" in a dedicated section, the provided tables demonstrate the device's performance against its intended use. For brevity, the "Overall" performance (combining prospective, retrospective, and contrived samples where applicable) is used here to represent the device's reported performance against implied high accuracy criteria.

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

The test set comprised a combination of clinical and contrived samples:

• Prospective Clinical Samples: 349 evaluable samples (167 fresh, 182 frozen). Patients were of all ages and genders. Collected at 7 clinical sites.
• Retrospective Clinical Samples: 577 evaluable samples. Collected at 10 clinical sites.
• Contrived Samples: 777 samples.

Data Provenance: The clinical samples (prospective and retrospective) were collected at multiple clinical sites, suggesting data from different countries/regions, but specific countries of origin are not detailed. Both prospective and retrospective collection methods were used.

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

The document does not explicitly state the number of experts or their specific qualifications (e.g., radiologist with 10 years of experience) used to establish the ground truth. It refers to "standard laboratory procedures for identification of blood culture isolates, including traditional and automated identification methods, MALDI-TOF IVD, and microbiological and biochemical techniques" as the comparator method. For Acinetobacter baumannii and Candida parapsilosis, as well as antibiotic resistance genes, PCR assays followed by bi-directional sequencing were used for confirmation. This implies a reliance on established laboratory protocols and potentially expert interpretation within those processes, but specific expert count or detailed qualifications are not provided.

4. Adjudication Method for the Test Set

The document does not describe an explicit adjudication method (e.g., 2+1, 3+1). The "Comparator Method" served as the reference standard and was used to determine true positive (TP), false negative (FN), true negative (TN), and false positive (FP) results. Discrepancies were investigated using PCR/sequencing (as noted in footnotes for various tables), suggesting a re-evaluation process for conflicting results but not a formal multi-reader adjudication scheme for the initial ground truth establishment.

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

No MRMC comparative effectiveness study involving human readers and AI assistance was performed or described in the provided text. The study focuses on the standalone performance of the ePlex BCID-GN Panel against laboratory reference methods.

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

Yes, the study described is a standalone performance study of the ePlex BCID-GN Panel. The performance metrics (PPA and NPA) are calculated by comparing the device's output directly against the "Comparator Method" without human interpretation influencing the device's result.

7. The Type of Ground Truth Used

The ground truth was established using expert consensus methods based on standard laboratory procedures for organism identification and analytically validated molecular assays (qPCR followed by bi-directional sequencing) for confirming specific organisms and resistance genes. This includes:

• Traditional and automated identification methods
• MALDI-TOF IVD
• Microbiological and biochemical techniques
• PCR/sequencing for specific organisms and resistance markers.

8. The Sample Size for the Training Set

The document does not mention a distinct "training set" in the context of the clinical performance evaluation. The clinical studies (prospective, retrospective, and contrived samples) are described as evaluation/test sets. However, the "Analytical Reactivity (Inclusivity)" and "Limit of Detection (LoD)" studies (Tables 56 and 57) describe testing of various strains and isolates to establish the device's analytical performance and broad reactivity. These analytical studies are crucial for the development and "training" (in a broader sense of assay design and validation) of such molecular diagnostic panels.

Specifically:

• Limit of Detection (LoD): At least 20 replicates per target were tested for each condition using quantified reference strains (Table 56 lists 38 organisms/targets with specific strains).
• Analytical Reactivity (Inclusivity): A panel of 336 strains/isolates was evaluated (Table 57 provides a partial list of these validated strains).
• Predicted (in silico) Reactivity: Bioinformatic analysis covered many additional variants for genus/group assays and resistance markers (Tables 58-76).

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

For the analytical "training" aspects:

• LoD: The ground truth for LoD was established by using quantified reference strains with known concentrations in simulated blood culture sample matrix. The lowest concentration detected in ≥95% of tested replicates was defined as the LoD.
• Analytical Reactivity (Inclusivity): The ground truth was established by testing well-characterized strains/isolates with known identities at specified concentrations, confirming their detection by the panel.
• Predicted (in silico) Reactivity: This involved bioinformatic analysis of existing sequence data for various organisms and resistance gene variants to predict the panel's ability to detect them. This is a computational method for establishing theoretical ground truth based on genetic sequences.

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The GenMark ePlex Blood Culture Identification Fungal Pathogen (BCID-FP) Panel is a qualitative nucleic acid multiplex in vitro diagnostic test intended for use on GenMark's ePlex Instrument for simultaneous detection and identification of multiple potentially pathogenic fungal organisms in positive blood culture. The ePlex BCID-FP Panel is performed directly on blood culture samples identified as positive by a continuous monitoring blood culture system and which contain fungal organism.

The following fungal organisms are identified using the ePlex BCID-FP Panel: Candida albicans, Candida auris, Candida dubliniensis, Candida famata, Candida glabrata, Candida guilliermondii, Candida kefyr, Candida krusei, Candida lusitaniae, Candida parapsilosis, Candida tropicalis, Cryptococcus gattii, Cryptococcus neoformans, Fusarium and Rhodotorula.

The detection and identification of specific fungal nucleic acids from individuals exhibiting signs and/or symptoms of bloodstream infection aids in the diagnosis of bloodstream infection when used in conjunction with other clinical information. The results from the ePlex BCID-FP Panel are intended to be interpreted in conjunction with Gram stain results and should not be used as the sole basis for diagnosis, treatment, or other patient management decisions.

Negative results in the setting of a suspected bloodstream infection may be due to infection with pathogens that are not detected by this test. Positive results do not rule out co-infection with other organisms; the organism(s) detected by the ePlex BCID-FP Panel may not be the definite cause of disease. Additional laboratory testing (e.g. sub-culturing of positive blood cultures for identification of organisms not detected by ePlex BCID-FP Panel, susceptibility testing and differentiation of mixed growth) and clinical presentation must be taken into consideration in the final diagnosis of bloodstream infection.

The ePlex Blood Culture Identification Fungal Pathogen (BCID-FP) Panel is based on the principles of competitive nucleic acid hybridization using a sandwich assay format, wherein a single-stranded target binds concurrently to a sequence-specific solution-phase signal probe and a solid-phase electrode-bound capture probe. The test employs nucleic acid extraction, target amplification via polymerase chain reaction (PCR) or reverse transcription PCR (RT-PCR) and hybridization of target DNA. In the process, the double-stranded PCR amplicons are digested with exonuclease to generate single-stranded DNA suitable for hybridization.

Nucleic acid extraction from biological samples occurs within the cartridge via cell lysis, nucleic acid capture onto magnetic beads, and release for amplification. The nucleic acid extraction is processed through microfluidic liquid handling. Once the nucleic acid targets are captured and inhibitors are washed away, the magnetic particles are delivered to the electrowetting environment on the printed circuit board (PCB) and the targets are eluted from the particles and amplified.

During hybridization, the single-stranded target DNA binds to a complementary, single-stranded capture probe immobilized on the working gold electrode surface. Single-stranded signal probes (labeled with electrochemically active ferrocenes) bind to specific target sequence / region adjacent to the capture probe. Simultaneous hybridization of target to signal probes and capture probe is detected by alternating current voltammetry (ACV). Each working electrode on the array contains specific capture probes, and sequential analysis of each electrode allows detection of multiple analyte targets.

This document describes the analytical and clinical performance of the GenMark ePlex Blood Culture Identification Fungal Pathogen (BCID-FP) Panel, an in vitro diagnostic test. The information provided is sufficient to extract the requested details about acceptance criteria and study proving the device meets them.

1. Table of acceptance criteria and reported device performance:

The document implicitly defines acceptance criteria through the reported performance characteristics. While no explicit "acceptance criteria" table is provided, the clinical performance (Sensitivity/PPA and Specificity/NPA) tables against a comparator method serve as the primary evidence of meeting performance expectations. Analytical performance characteristics also define a form of acceptance criteria (e.g., LOD, exclusivity).

Here’s a table summarizing the reported device performance for each target organism, which represents the device meeting its performance objectives. The device demonstrates high sensitivity (positive percent agreement) and specificity (negative percent agreement) across various sample types (prospective, retrospective, and contrived).

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

The test set for evaluating clinical performance consisted of:

• Prospective Samples: 21 evaluable samples (11 fresh, 10 frozen) collected at 6 clinical sites. These samples are from patients of all ages and genders. Collection dates are specified from May 2015 through July 2016 (frozen) and July through August 2018 (fresh). The country of origin is not explicitly stated but implied to be the US given the FDA submission. This data is prospective.
• Retrospective Samples: 120 samples collected from 9 sites. This data is retrospective.
• Contrived Samples: 725 evaluable samples prepared by spiking isolates into blood culture bottles. These are laboratory-prepared samples.

The total number of samples evaluated for clinical performance was 866 (11 fresh prospective + 10 frozen prospective + 120 retrospective + 725 contrived).

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

The document does not specify the number of experts or their qualifications (e.g., radiologists with 10 years of experience) used to establish the ground truth. Instead, it relies on standard laboratory procedures and analytically validated PCR assays followed by bi-directional sequencing as the comparator methods (ground truth). This implies that the ground truth was established through a combination of traditional microbiological methods and molecular techniques, not through expert consensus reading of images or other subjective assessments.

4. Adjudication method for the test set:

The document describes the "comparator method" as the gold standard. For specific targets like Candida auris, Fusarium, Rhodotorula, and to confirm Candida parapsilosis, PCR/sequencing was used to determine the presence or absence of the organism, effectively acting as an adjudication step for these cases. For other organisms, standard laboratory procedures (culture, MALDI-TOF IVD, etc.) defined the ground truth. There is no mention of a traditional reader adjudication process (e.g., 2+1 or 3+1) as would be common in image-based AI studies, as this is a molecular diagnostic test. For discrepant results (e.g., section "Co-detections in Clinical Samples"), PCR/sequencing was used to investigate.

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 typically performed for AI-assisted diagnostic tools that involve human interpretation of images. The ePlex BCID-FP Panel is an in vitro diagnostic (IVD) test that directly detects and identifies genetic material, so human readers are not involved in its direct interpretation in the way they would be in an AI imaging study. Therefore, there is no effect size of how much human readers improve with AI vs without AI assistance.

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

Yes, the primary clinical performance evaluation is a standalone performance of the algorithm (the ePlex BCID-FP Panel) against a defined ground truth (comparator methods). The reported sensitivity/PPA and specificity/NPA values are purely the device's performance.

7. The type of ground truth used:

The ground truth for the clinical performance evaluation was established using:

• Standard laboratory procedures: This includes traditional and automated culture, MALDI-TOF IVD (Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry), and other microbiological and biochemical techniques.
• Analytically validated PCR assays followed by bi-directional sequencing: This advanced molecular method was used for specific targets (Candida auris, Fusarium, Rhodotorula) and to confirm certain identifications (Candida parapsilosis).

This represents a combination of expert consensus (through standard lab practices) and molecular outcomes data.

8. The sample size for the training set:

The document does not explicitly state the sample size for a "training set" in the context of machine learning. As this is a molecular diagnostic assay using nucleic acid hybridization and PCR, not a machine learning algorithm that learns from data in the same way, the concept of a distinct 'training set' for the device's core functionality specification might not apply directly in the conventional AI sense. The development of such assays involves analytical validation using numerous strains and concentrations (analytical reactivity, LOD, exclusivity), which implicitly serve as a form of "training" or optimization data during product development, but this is distinct from machine learning model training. The provided data focuses on the performance evaluation (test set) for regulatory approval.

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

Given that there isn't a "training set" in the typical machine learning sense, the way "ground truth" would be established for the development of such a molecular assay would involve:

• Known Reference Strains: Use of well-characterized microbial strains (e.g., ATCC, CBS, CDC strains) with confirmed identities. These are used in analytical studies like Limit of Detection (LOD) and Analytical Reactivity (Inclusivity), as well as Competitive Inhibition studies. Table 21 ("Contrived Sample Summary") and Table 27 ("Analytical Reactivity (Inclusivity) Results") list numerous specific strains and their origins (e.g., ATCC, CBS, NCPF, CDC#) used in testing.
• Sequencing and Phenotypic Characterization: During the assay's development, target sequences would be determined through genome sequencing, and phenotypic characteristics would be confirmed through established microbiological methods.

Therefore, the "ground truth" during device development (analogous to training/development data in AI) relies on well-characterized laboratory standards and molecular gold standards.

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The GenMark ePlex Blood Culture Identification Gram-Positive (BCID-GP) Panel is a qualitative nucleic acid multiplex in vitro diagnostic test intended for use on GenMark's ePlex Instrument for simultaneous qualitative detection and identification of multiple potentially pathogenic gram-positive bacterial organisms and select determinants associated with antimicrobial resistance in positive blood culture. In addition, the ePlex BCID-GP Panel is capable of detecting a wide variety of gram-negative bacteria (Pan Gram-Negative assay) and several Candida species (Pan Candida assay). The ePlex BCID-GP Panel is performed directly on blood culture samples identified as positive by a continuous monitoring blood culture system and which contain gram-positive organism.

The following bacterial organisms and genes associated with antibiotic resistance are identified using the ePlex BCID-GP Panel: Bacillus cereus group, Bacillus subtilis group, Corynebacterium, Cutibacterium acnes (Propionibacterium acnes), Enterococcus, Enterococcus faecalis, Enterococcus faecium, Lactobacillus, Listeria monocytogenes, Micrococcus, Staphylococcus, Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus lugdunensis, Streptococcus agalactiae (GBS), Streptococcus anginosus group, Streptococcus pneumoniae, Streptococcus pyogenes (GAS), mecA, mecC, vanA and vanB.

The ePlex BCID-GP Panel contains assays for the detection of genetic determinants associated with resistance to methicillin (mecA and mecC) to aid in the identification of potentially antimicrobial resistant organisms in positive blood culture samples. The antimicrobial resistance gene detected may or may not be associated with the agent responsible for disease.

The ePlex BCID-GP Panel also contains targets designed to detect a broad range of organisms with a potentially misleading Gram stain result or organisms that may be missed by Gram staining altogether, for example in the case of co-infections. These include a broad Pan Gram-Negative assay as well as a Pan Candida assay, which is designed to detect four of the most prevalent Candida species: Candida albicans, Candida glabrata, Candida krusei and Candida parapsilosis.

The detection and identification of specific bacterial and fungal nucleic acids from individuals exhibiting signs and/or symptoms of bloodstream infection aids in the diagnosis of bloodstream infection when used in conjunction with other clinical information. The results from the ePlex BCID-GP Panel are intended to be interpreted in conjunction with Gram stain results and should not be used as the sole basis for diagnosis, treatment, or other patient management decisions.

Negative results in the setting of a suspected bloodstream infection may be due to infection with pathogens that are not detected by this test. Positive results do not rule out co-infection with other organisms; the organism(s) detected by the ePlex BCID-GP Panel may not be the definite cause of disease. Additional laboratory testing (e.g. sub-culturing of positive blood cultures for identification of organisms not detected by ePlex BCID-GP Panel and for susceptibility testing. differentiation of mixed growth and association of antimicrobial resistance marker genes to a specific organism) and clinical presentation must be taken into consideration in the final diagnosis of blood stream infection.

The ePlex Blood Culture Identification Gram-Positive (BCID-GP) Panel is based on the principles of competitive nucleic acid hybridization using a sandwich assay format, wherein a single-stranded target binds concurrently to a sequence-specific solution-phase signal probe and a solid-phase electrode-bound capture probe. The test employs nucleic acid extraction, target amplification via polymerase chain reaction (PCR) or reverse transcription PCR (RT-PCR) and hybridization of target DNA. In the process, the double-stranded PCR amplicons are digested with exonuclease to generate single-stranded DNA suitable for hybridization.

Nucleic acid extraction from biological samples occurs within the cartridge via cell lysis, nucleic acid capture onto magnetic beads, and release for amplification. The nucleic acid extraction is processed through microfluidic liquid handling. Once the nucleic acid targets are captured and inhibitors are washed away, the magnetic particles are delivered to the electrowetting environment on the printed circuit board (PCB) and the targets are eluted from the particles and amplified.

During hybridization, the single-stranded target DNA binds to a complementary, single-stranded capture probe immobilized on the working gold electrode surface. Single-stranded signal probes (labeled with electrochemically active ferrocenes) bind to specific target sequence / region adjacent to the capture probe. Simultaneous hybridization of target to signal probes and capture probe is detected by alternating current voltammetry (ACV). Each working electrode on the array contains specific capture probes, and sequential analysis of each electrode allows detection of multiple analyte targets.

Here's an analysis of the provided text to extract information about the device's acceptance criteria and the study proving it meets them.

The document is a 510(k) Premarket Notification from the FDA regarding the GenMark ePlex Blood Culture Identification Panel - Gram Positive (BCID-GP) Panel (K181663). The core of the performance data revolves around clinical performance (sensitivity/PPA and specificity/NPA) against comparator methods, and analytical performance (Limit of Detection, Inclusivity, Exclusivity, Reproducibility, Interfering Substances, Competitive Inhibition).

Acceptance Criteria and Reported Device Performance

The acceptance criteria are implicitly defined by the clinical and analytical performance targets the device aimed to meet, typically demonstrating non-inferiority or substantial equivalence to a predicate device and adequate analytical performance. The tables provided (Table 6 through Table 30 for clinical performance, and Table 61 onwards for reproducibility) present the device's reported performance. A formal table of acceptance criteria with corresponding results isn't explicitly laid out with a "criteria" column alongside "performance" in the document, but we can infer the criteria from the achieved results and the FDA clearance itself, which implies acceptable performance.

For this device, the primary acceptance criteria would be high Positive Percent Agreement (PPA) and Negative Percent Agreement (NPA) with established comparator methods for all targeted organisms and resistance genes, along with robust analytical performance.

Here's a summary of the reported performance, reflecting the device meeting implicit acceptance criteria for clinical accuracy:

Table 1: Derived Acceptance Criteria and Reported Device Performance (Selected Examples)

Detailed Information about the Study:

1. A table of acceptance criteria and the reported device performance

   • See the table above for inferred criteria and reported performance based on clinical PPA/NPA. The acceptance criteria are not explicitly stated as quantitative thresholds in the provided text, but the successful clearance of the device implies that the observed performance was deemed acceptable by the FDA.

2. Sample sizes used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)

   • Test Set (Clinical Study):
     • Prospective Samples: Total 711 evaluable samples. Collected from 7 clinical sites. 312 were tested fresh (Jan-Feb 2018), and 399 were frozen (June 2014-July 2016).
     • Retrospective Samples: Total 586 evaluable samples. Collected to supplement low prevalence targets.
     • Combined Clinical Samples: 1297 (711 prospective + 586 retrospective).
     • Contrived Samples: 565 samples prepared by spiking isolates into blood culture bottles.
   • Data Provenance: The document states "A prospective, multicenter clinical study was conducted at 7 clinical sites." While specific countries are not mentioned, FDA clearances typically involve studies predominantly conducted in the USA or with data acceptable to US regulatory standards. The terms "multicenter" and "clinical sites" imply different geographical locations although not explicitly named.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience)

   • The ground truth for the clinical test set was established using "Standard laboratory procedures" including traditional and automated culture, MALDI-TOF IVD, and microbiological and biochemical techniques for organism identification. Specific PCR assays followed by bi-directional sequencing (or 16S sequencing for Corynebacterium, Staphylococcus epidermidis, Candida parapsilosis) were used for confirmation where necessary. For antibiotic resistance genes (mecA, mecC, vanA, vanB), ground truth was established using analytically validated qPCR amplification assays followed by bi-directional sequencing.
   • The document does not specify the number of experts or their qualifications (e.g., board-certified microbiologists, medical technologists with X years of experience) who performed these standard laboratory procedures or interpreted the sequencing results to establish ground truth.

4. Adjudication method (e.g. 2+1, 3+1, none) for the test set

   • The document describes a comparison between the ePlex BCID-GP Panel results and "comparator method(s) results." For discrepant results (e.g., false positives, false negatives), additional analytically validated PCR assays and sequencing were used for confirmation (e.g., for Corynebacterium, S. epidermidis, Pan Candida, Staphylococcus for mecA, and Enterococcus for vanA/vanB).
   • This is a form of adjudication, where discrepant results are further investigated. However, it's not a multi-reader adjudication method (like 2+1, 3+1) involving multiple human readers interpreting results, as this device performs automated detection. Instead, it's a discrepancy resolution method using a higher-level, analytically validated diagnostic test (PCR/sequencing) as the tie-breaker/confirmatory 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, an MRMC comparative effectiveness study was not done. This device is an in vitro diagnostic test for identifying microorganisms and resistance markers, not an AI-assisted diagnostic imaging or interpretation tool for human readers. Its performance is evaluated against laboratory standard reference methods, not against human reader performance or improvement with AI assistance.

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

   • Yes, the primary clinical and analytical performance studies are standalone (algorithm only) performance. The ePlex BCID-GP Panel is an automated test on the ePlex Instrument. Its results are generated by the device's assay and software, and then compared directly to the ground truth established by comparator laboratory methods. There is no explicit human-in-the-loop component described for its diagnostic performance evaluation, although clinical interpretation of the results by medical professionals is clearly indicated as necessary for patient management decisions (as stated in the Indications for Use).

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc)

   • The ground truth for the clinical study was based on "Standard laboratory procedures" for organism identification (culture, MALDI-TOF IVD, microbiological/biochemical techniques) and analytically validated PCR assays with bi-directional sequencing for confirmation of specific organisms and all resistance genes. This would fall under laboratory reference standard/molecular confirmation. Clinical outcomes data was not primarily used for ground truth.

8. The sample size for the training set

   • The document does not specify a separate "training set" size for the development of the ePlex BCID-GP Panel's algorithm. For in vitro diagnostic devices like this one, the development process might involve internal validation and optimization, but the regulatory submission focuses on the performance of the final, locked version of the device using a clinically representative "test set." The text primarily describes the clinical evaluation (prospective, retrospective, contrived samples) which serves as the independent test set for regulatory submission.

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

   • As a distinct "training set" is not explicitly mentioned as per typical machine learning contexts, the document doesn't detail how ground truth for such a set was established. It's plausible that internal development and optimization would have used similar laboratory reference methods as those used for the clinical validation.

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The ePlex® Respiratory Pathogen (RP) Panel is a multiplexed nucleic acid in vitro diagnostic test intended for use on the ePlex® Instrument for the simultaneous qualitative detection and identification of multiple respiratory viral and bacterial nucleic acids in nasopharyngeal swabs (NPS) obtained from individuals exhibiting signs and symptoms of respiratory tract infection.

The following virus types, subtypes, and bacteria are identified using the ePlex RP Panel: adenovirus, coronavirus, human metapneumovirus, human rhinovirus/enterovirus, influenza A, influenza A H1, influenza A H1-2009, influenza A H3, influenza B, parainfluenza virus 1, parainfluenza virus 2, parainfluenza virus 3, parainfluenza virus 4, respiratory syncytial virus (RSV) A, respiratory syncytial virus (RSV) B, Chlamydia pneumoniae, and Mycoplasma pneumoniae.

The detection and identification of specific viral and bacterial nucleic acids from individuals exhibiting signs and/or symptoms of respiratory tract infection aids in the diagnosis of respiratory infection when used in conjunction with other clinical and epidemiological information. The results of this test should not be used as the sole basis for diagnosis, treatment, or other patient management decisions.

Negative results in the setting of a respiratory illness may be due to infection with pathogens that are not detected by this test, or lower respiratory tract infection that may not be detected by a nasopharyngeal swab specimen. Positive results do not rule out co-infection with other organisms; the organism(s) detected by the ePlex RP Panel may not be the definite cause of disease. Additional laboratory testing (e.g. bacterial and viral culture, immunofluorescence, and radiography) may be necessary when evaluating a patient with possible respiratory tract infection.

Due to the genetic similarity between human rhinovirus and enterovirus, the ePlex RP Panel cannot reliably differentiate them. If differentiation is required, an ePlex RP Panel positive human rhinovirus/enterovirus result should be followed-up using an alternative method (e.g., cell culture or sequence analysis).

Performance characteristics for influenza A were established when influenza A H1-2009 and A H3 were the predominant influenza A viruses in circulation. Performance of detecting influenza A may vary if other influenza A strains are circulating or a novel influenza A virus emerges. If infection with a novel influenza A virus is suspected based on current clinical and epidemiological screening criteria recommended by public health authorities, specimens should be collected with appropriate infection control precautions for novel virulent influenza viruses and sent to state or local health departments for testing. Viral culture should not be attempted in these cases unless a BSL-3+ facility is available to receive and culture specimens.

The ePlex RP Panel is an automated qualitative nucleic acid multiplex in vitro diagnostic test for simultaneous detection and identification of multiple respiratory viral and bacterial nucleic acids in nasopharyngeal swabs (NPS). The test is able to detect 15 respiratory viral targets and 2 bacterial targets as summarized in the table below. This test is performed on the ePlex Instrument.

The ePlex Instrument automates all aspects of nucleic acid testing including extraction, amplification, and detection, combining electrowetting and GenMark's eSensor® technology in a single-use cartridge. eSensor technology is based on the principles of competitive DNA hybridization and electrochemical detection. which is highly specific and is not based on fluorescent or optical detection.

Electrowetting, or digital microfluidics, uses electrical fields to directly manipulate discrete droplets on the surface of a hydrophobically coated printed circuit board (PCB). Sample and reagents are moved in a programmable fashion in the ePlex cartridge to complete all portions of the sample processing from nucleic acid extraction to detection.

A sample is loaded onto the ePlex cartridge and nucleic acids are extracted and purified from the specimen via magnetic solid phase extraction. For RNA targets, a reverse transcription step is performed to generate complementary DNA from the RNA. followed by PCR to amplify the targets. Exonuclease digestion creates single-stranded DNA in preparation for eSensor detection.

The target DNA is mixed with ferrocene-labeled signal probes that are complementary to the specific targets on the panel. Target DNA hybridizes to its complementary signal probe and capture probes, which are bound to gold-plated electrodes. The presence of each target is determined by voltammetry which generates specific electrical signals from the ferrocenelabeled signal probe.

The acceptance criteria and study proving the device meets them are summarized below. It should be noted that this document focuses on the ePlex Respiratory Pathogen (RP) Panel, which is an in vitro diagnostic test, not an AI medical device. Therefore, several requested sections (e.g., number of experts for ground truth, adjudication method, MRMC study, sample size for training set) are not applicable as they pertain to image-based AI studies.

1. Table of Acceptance Criteria and Reported Device Performance

For an in vitro diagnostic test like the ePlex RP Panel, acceptance criteria are typically defined by performance metrics such as Positive Percent Agreement (PPA) and Negative Percent Agreement (NPA) with a comparator method. The study aims to demonstrate that the device performs equivalently to or better than established methods.

Note: The document does not explicitly state numerical acceptance criteria. The "Implicit Acceptance Criteria" are inferred as generally high agreement rates required for diagnostic tests to demonstrate substantial equivalence to predicate devices.

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

• Prospective Clinical Samples:
  • Sample Size: 2462 evaluable samples collected.
  • Data Provenance: Prospectively-collected at 8 clinical sites (presumably in the USA, as this is an FDA submission).
  • Collection Phases:
    • Phase 1: March 2013 - August 2014 (1951 samples, frozen)
    • Phase 2: September 2016 - October 2016 (511 samples, fresh)
  • Patient Population: Individuals of all ages and genders exhibiting signs and/or symptoms of respiratory tract infection.
• Retrospective Clinical Samples (to supplement positives for low prevalence targets):
  • Sample Size: 446 evaluable samples.
  • Data Provenance: Retrospectively collected from 6 sites (presumably in the USA), previously tested positive for one or more target organisms during standard-of-care (SOC) testing. Stored frozen.
• Contrived Samples (to supplement low prevalence targets):
  • Sample Size: 327 contrived samples (104 positive for one or more low prevalence organisms, 223 negative for contrived organisms).
  • Data Provenance: Lab-generated by spiking viral/bacterial cultures into a natural clinical matrix (pooled, negative nasopharyngeal swab in VTM samples).

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

Not applicable. This is an in vitro diagnostic device study, not an AI medical device study involving expert interpretation of images or clinical data. Ground truth was established by laboratory methods.

4. Adjudication Method for the Test Set

Not applicable in the typical sense of expert adjudication for AI interpretation. Discrepant results between the ePlex RP Panel and the comparator method were investigated using PCR/sequencing (as detailed in footnotes of Tables 7, 8, 10, 12, and 13). This serves as a molecular adjudication method to refine the ground truth.

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 type of study is relevant for evaluating the impact of AI assistance on human reader performance, which doesn't apply to this molecular diagnostic device.

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

Yes, the performance study effectively evaluates the ePlex RP Panel in a standalone manner. The device automates nucleic acid testing, and its results are compared against a laboratory-based (molecular) comparator method. There is no "human-in-the-loop" component in the interpretation or direct performance of the ePlex RP Panel that would necessitate studying its effect on human readers.

7. The Type of Ground Truth Used (expert consensus, pathology, outcomes data, etc.)

The ground truth for the clinical performance evaluation was established using:

• FDA-cleared multiplexed molecular respiratory pathogen panels (serving as the primary comparator method).
• Analytically validated PCR tests with bi-directional sequencing for confirmation, especially for RSV subtypes and to resolve discrepancies.

For analytical studies (LoD, inclusivity, specificity), the ground truth was based on known concentrations of quantified reference strains/isolates.

8. The Sample Size for the Training Set

Not applicable. This is not an AI/machine learning study where a distinct "training set" is used to develop an algorithm. The device's design and analytical parameters are established through laboratory development and validation, not through learning from a large, labeled dataset in the way an AI model would be trained.

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

Not applicable, as there is no "training set" in the context of this molecular diagnostic device. The device's reagents and detection mechanisms are designed based on known genetic sequences of the target pathogens.

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The ePlex Instrument is an automated in vitro diagnostic (IVD) device designed to perform multiplexed nucleic acid tests for the simultaneous detection and identification of nucleic acid targets by processing single-use cartridges developed and manufactured by GenMark Diagnostics, Inc.

The ePlex® Instrument is used to run single-use assay cartridges that incorporate digital microfluidics and GenMark's eSensor® detection technology (used by products that are currently FDA-cleared: K073720 and K090901) to automate all aspects of nucleic acid testing. The ePlex Instrument is designed to: provide a nucleic acid amplification testing solution directly from various sample types, provide random access testing capability, and require minimal operator interaction.

The ePlex Instrument includes the following components:

• . Base: A touchscreen graphical user interface (GUI) powered by a PC with a Windows Operating System 7. The base communicates with the bays to transfer data. The instrument software installed on the ePlex base processes the raw data generated by the individual bays and determines the test result.
• Tower: A chassis housing six bays. ePlex is scalable from one to four towers . connected to either side of the base.
• . Bay: 6 bays are housed in each tower. Each bay will accept cartridges independent of the testing status of the other bays allowing for random access testing. Each bay has an Ethernet port for communication with the base unit to receive user inputs and deliver test data to the ePlex Instrument software.

The touchscreen graphical user interface (GUI) is flanked on either side by a tower with six bays containing a slot for the cartridge and an LED to indicate bay status (in-use or available for use). The instrument is designed to be scalable with configurations to accommodate a single tower with 6 bays or up to four towers with 24 bays.

The ePlex system is used to run multiplex microarray-based assays developed by GenMark. This type of assay is based on the principles of competitive nucleic acid hybridization using a sandwich assay format, wherein a single-stranded target binds concurrently to a sequencespecific solution-phase signal probe and a solid-phase electrode-bound capture probe. The test employs nucleic acid extraction, target amplification via polymerase chain reaction (PCR) or reverse transcription PCR (RT-PCR) and hybridization of target DNA. In the process, the double-stranded PCR amplicons are digested with exonuclease to generate single-stranded DNA suitable for hybridization.

Nucleic acid extraction from biological samples occurs within the cartridge via cell lysis, nucleic acid capture onto magnetic beads, and release for amplification. The nucleic acid extraction is processed through microfluidic liquid handling. Once the nucleic acid targets are captured and inhibitors are washed away, the magnetic particles are delivered to the electrowetting environment on the printed circuit board (PCB) and the targets are eluted from the particles and amplified.

During hybridization, the single-stranded target DNA binds to a complementary, singlestranded capture probe immobilized on the working gold electrode surface. Single-stranded signal probes (labeled with electrochemically active ferrocenes) bind to specific target sequence / region adjacent to the capture probe. Simultaneous hybridization of target to signal probes and capture probe is detected by alternating current voltammetry (ACV). Each working electrode on the array contains specific capture probes, and sequential analysis of each electrode allows detection of multiple analyte targets.

Here's an analysis of the acceptance criteria and study information provided for the GenMark Diagnostics, Inc. ePlex Instrument, based on the provided text:

Important Note: The provided document is a 510(k) summary for the ePlex Instrument itself, not a specific assay. It states that detailed clinical performance data will be included in the traditional 510(k) for the ePlex RP Panel. Therefore, the information below primarily relates to the instrument's performance as demonstrated through a reproducibility study, rather than the diagnostic accuracy of a specific assay.

1. Table of Acceptance Criteria and Reported Device Performance

The document mentions that acceptance criteria were established in advance for the reproducibility study and all were met. However, it does not explicitly list the quantitative acceptance criteria or the specific reported device performance metrics (e.g., specific percentages for run validity, agreement, or variability) for the ePlex Instrument in the provided text.

In the context of the ePlex Instrument, the reported performance is qualitative:

2. Sample Size and Data Provenance for the Test Set

• Test Set Description: The test set for the reproducibility study consisted of samples prepared at three concentration levels: moderate (3x LoD), low (1x LoD), and negative. These samples were run as a panel.
• Sample Size: The exact number of individual samples or runs used in the reproducibility study is not specified in the provided document. It states "samples prepared as a panel at moderate (3x LoD), low (1x LoD) and negative."
• Data Provenance: The study was conducted at three separate testing sites, implying multi-site data collection. The country of origin is not explicitly stated, but given the FDA submission, it is likely the United States. It was a prospective study as it was specifically conducted to evaluate the instrument's reproducibility.

3. Number of Experts and Qualifications for Ground Truth

• Ground Truth Establishment: For the reproducibility study of the instrument, the ground truth would likely be based on the known state of the prepared samples (i.e., 'positive' at specific concentrations or 'negative'). Therefore, the concept of "experts establishing ground truth" in the traditional sense (e.g., radiologists reviewing images) is not directly applicable here. The ground truth is intrinsic to the sample preparation.
• Number of Experts: Not applicable in this context.
• Qualifications of Experts: Not applicable in this context.

4. Adjudication Method for the Test Set

• Adjudication Method: Not applicable. The nature of a reproducibility study with pre-defined positive/negative samples at specific concentrations doesn't typically involve expert adjudication of results. The "truth" is determined by the sample preparation.

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

• MRMC Study: No, a multi-reader multi-case (MRMC) comparative effectiveness study was not mentioned as part of the ePlex Instrument's submission. This type of study would be more relevant for evaluating the impact of an AI-powered diagnostic algorithm on human performance, which is not the primary focus of this instrument submission.
• Effect Size: Not applicable.

6. Standalone Performance Study

• Standalone Performance: Yes, the reproducibility study evaluated the standalone performance of the ePlex Instrument. It assessed the instrument's ability to consistently generate results based on its internal processes (cell disruption, nucleic acid extraction, RT-PCR, single-stranding, signal detection) when processing known samples. The study evaluated "run validity, agreement, and variability."

7. Type of Ground Truth Used

• Ground Truth Type: The ground truth used was based on known sample preparation. Samples were intentionally prepared at specific concentrations (3x Limit of Detection, 1x Limit of Detection) or as negative controls. This is a form of analytical gold standard derived from controlled experimental design.

8. Sample Size for the Training Set

• Training Set Size: The document does not specify a separate training set size for the ePlex Instrument itself. This is expected because the ePlex Instrument is hardware, and while it contains software, the "training" in the AI/machine learning sense isn't explicitly discussed here for the instrument's core functions. Any algorithm "training" would likely be specific to individual assays run on the instrument (e.g., for interpreting an RP panel), and that information is deferred to the specific assay 510(k) submission.

9. How Ground Truth for the Training Set Was Established

• Ground Truth Establishment for Training Set: Since a separate training set for the instrument's core functionality is not described, the method of establishing ground truth for such a set is not provided in this document. If the instrument's software incorporates machine learning for result interpretation (beyond simple thresholding), that information would typically be detailed in the specific assay submission for which the training was performed.

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The eSensor® Warfarin Sensitivity Saliva Test is an in vitro diagnostic for the detection and genotyping of the *2 and *3 alleles of the cytochrome P450 (CYP450) 2C9 gene locus and the Vitamin K epoxide reductase C1 (VKORC1) gene promoter polymorphism (-1639G>A) from genomic DNA extracted from human saliva samples collected using the Oragene® Dx and ORAcollect® Dx devices, as an aid in the identification of patients at risk for increased warfarin sensitivity.

The eSensor® XT-8 instrument is an in vitro diagnostic device intended for genotyping multiple mutations or polymorphisms in an amplified DNA sample utilizing electrochemical detection technology.

The kit consists of the eSensor® Warfarin Sensitivity Saliva Test cartridge, the eSensor® Warfarin Sensitivity Saliva Test amplification reagents (including PCR mix and DNA polymerase), the eSensor® Warfarin Sensitivity Saliva Test detection reagents (including exonuclease, probes and hybridization buffer ingredients) and the eSensor® XT-8 System. One eSensor® Warfarin Sensitivity Saliva Test Kit has sufficient materials for 24 tests.

The provided document, a 510(k) summary for the eSensor® Warfarin Sensitivity Saliva Test, details performance data primarily focused on a new specimen collection kit (ORAcollect®·Dx Device) and its impact on the existing device's performance. The study aims to demonstrate that incorporating this new collection kit does not compromise the accuracy or reliability of the Warfarin Sensitivity Saliva Test.

Here's an analysis of the acceptance criteria and study findings:

1. Table of Acceptance Criteria and Reported Device Performance

The document doesn't explicitly state 'acceptance criteria' in terms of specific numerical thresholds for accuracy, reproducibility, or call rates. However, the studies consistently aim for 100% agreement with the ground truth (bi-directional sequencing), and 100% correct calls with 0% incorrect calls. The "Method Comparison" section indicates an aspiration for high concordance and call rate.

2. Sample Sizes and Data Provenance

• Reproducibility (Sample-to-Sample, Lot-to-Lot, Day-to-Day, Operator-to-Operator):

  • Test set sample size: 10 donors, with 3 samples each (total 30 samples collected). These were processed by 3 operators, with genotyping data evaluated for each operator for each of the 3 SNPs. This implies 20 tests per SNP per operator (based on the "20" under "Samples Tested" for each SNP for each operator), totaling 60 tests per SNP across all operators, or 120 calls per SNP when considering all samples and operators for the "Summary of Results by Sample and Genotype" table.
  • Data Provenance: Not explicitly stated, but likely prospective and from a controlled lab environment.

• Multi-center Reproducibility:

  • Test set sample size: 30 donors. Multiple saliva samples collected from each.
  • Data Provenance: Saliva samples were collected from 3 sites. Two sites were described as "professional setting" with "supervised collections," and the third site had "unsupervised collections." One sample from each donor was transported to three independent sites for extraction. All eSensor Warfarin Sensitivity Saliva testing was conducted at Site 1. This suggests a prospective data collection design, with samples from multiple (unspecified) locations. No country of origin is mentioned.

• Method Comparison:

  • Test set sample size: 156 saliva samples.
  • Data Provenance: Not explicitly stated, but implies a prospective or retrospectively collected set of human saliva samples. No country of origin is mentioned.

• Interfering Substances (Endogenous):

  • Test set sample size: 14 donors, each providing 4 saliva samples.
  • Data Provenance: Not explicitly stated, but likely prospective, controlled lab study.

• Interfering Substances (Exogenous):

  • Test set sample size: Varied per activity, ranging from 5 to 9 donors per activity group. Each donor provided samples at two time-points (immediate and 30 minutes post-activity).
  • Data Provenance: Not explicitly stated, but likely prospective, controlled lab study.

3. Number of Experts and Qualifications for Ground Truth

The ground truth for all studies was established by bi-directional DNA sequencing. This is a laboratory-based method, not typically requiring "experts" in the sense of clinical specialists. The interpretation of sequencing results is a standard molecular biology technique. No specific number of experts or their qualifications (e.g., geneticists, molecular biologists) are mentioned for establishing the ground truth, as it's assumed to be a direct, objective measurement.

4. Adjudication Method for the Test Set

The studies used bi-directional DNA sequencing as the gold standard, not a human expert adjudication process. The agreement was calculated directly between the device's genotypes and the sequencing results. If there were discrepancies in the initial device results (e.g., initial miscalls or no-calls in the method comparison), retests were performed. For instance, in the method comparison, two miscalls were attributed to "operator error (sample mix-up) occurring during the first XT8 testing" and one remaining no-call to "an operator error at the purification step." This suggests an internal investigation and re-testing process rather than an external adjudication panel.

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

No Multi-Reader Multi-Case (MRMC) comparative effectiveness study was done. This device is a diagnostic test for genotyping, not an imaging device or a system requiring human interpretation with or without AI assistance. Therefore, the concept of "readers improving with AI vs. without AI" is not applicable here. The device itself performs the genotyping.

6. Standalone Performance Study

Yes, a standalone performance study was done. All the performance data described (reproducibility across operators/sites, method comparison with sequencing, and interfering substances studies) directly assesses the performance of the eSensor® Warfarin Sensitivity Saliva Test (algorithm/device only, without human-in-the-loop performance influencing the genotyping call itself, though human operators are involved in sample preparation and running the test). The percentage agreement and call rates reflect the direct output of the device compared to the ground truth.

7. Type of Ground Truth Used

The primary ground truth used for all studies was bi-directional DNA sequencing. This is a highly accurate molecular method for determining genetic sequences and polymorphisms (genotypes).

8. Sample Size for the Training Set

The document is a 510(k) summary for a labeling modification (addition of a new specimen collection kit) to an already cleared device. It primarily presents validation data for the continued performance of the device with the new collection kit. It does not mention a "training set" for the eSensor® Warfarin Sensitivity Saliva Test itself, as this device likely relies on established molecular biology principles and probes designed against known genetic targets, rather than machine learning algorithms that require extensive training data. It's a deterministic diagnostic test, not an AI model that learns from data in the way a computer vision algorithm would.

9. How Ground Truth for the Training Set Was Established

As noted above, the concept of a "training set" doesn't directly apply in the context of this device. The device's design is based on known genetic sequences and electrochemical detection rather than a machine learning model. The validation studies verify its performance against the established ground truth of bi-directional DNA sequencing.

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