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The BD GeneOhm™ MRSA ACP Assay is a qualitative in vitro diagnostic test for the direct detection of methicillin-resistant Staphylococcus aureus (MRSA) DNA from nasal swabs in patients at risk for nasal colonization. The test utilizes polymerase chain reaction (PCR) for the amplification of MRSA DNA and fluorogenic target-specific hybridization probes for the detection of the amplified DNA. The BD GeneOhm™ MRSA ACP Assay is intended to aid in the prevention and control of MRSA infections in healthcare settings. It is not intended to diagnose MRSA infections nor to guide or monitor treatment for MRSA infections. Concomitant cultures are necessary only to recover organisms for epidemiological typing or for further susceptibility testing.

The BD GeneOhm™ MRSA ACP Assay is a qualitative in vitro diagnostic test for the direct detection of methicillin-resistant Staphylococcus aureus (MRSA) DNA from nasal swabs. A nasal specimen is collected and transported to the laboratory using a recommended swab. The lysis of bacterial cells in nasal swab specimens is performed using the BD GeneOhm™ MRSA ACP Lysis kit. An aliquot of the lysate is added to prepared PCR reagents which contain MRSA-specific primers that will amplify in the presence of genetic target. The assay also includes an Internal Control (IC) to monitor for the presence of inhibitors in the PCR reaction and to confirm the integrity of assay reagents. Controls and specimen lysates are added to disposable reaction tubes and placed in the SmartCycler® II instrument. The amplification, detection and results interpretation are automatically performed by the SmartCycler® II software. The BD GeneOhm™ MRSA ACP Assay procedure can be performed within 2 hours, depending on the number of specimens processed. To recover MRSA for epidemiological typing or for further antibiotic susceptibility testing, appropriate culture media can be inoculated during or up to 24 hours after specimen preparation. The primers and probes in the BD GeneOhm™ MRSA ACP Assay detect a proprietary sequence inserted into the S. aureus chromosome indicating the presence of MRSA DNA. Amplification of IC and MRSA DNA are detected using specific hybridization probes that bind to a specific sequence of the amplified target. Differentiation of MRSA DNA and IC is done using molecular beacons which contain different fluorometric properties. The beacon-target hybrid fluoresces at a different wavelength for MRSA and IC and the emitted light from this reaction is measured by the SmartCycler® II instrument. MRSA or IC specific amplicons are detected simultaneously in two different fluorescence channels on the SmartCycler and can therefore be differentiated. The operation of the SmartCycler® II instrument is based on the proprietary microprocessor-controlled I-CORE® (Intelligent Cooling/Heating Optical Reaction) module.

Here's a summary of the acceptance criteria and the study that proves the device (BD GeneOhm™ MRSA ACP Assay) meets them, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance:

The document doesn't explicitly state "acceptance criteria" as a separate, pre-defined set of values. Instead, it presents performance data from a clinical trial and analytical studies. Here, I've inferred the implied acceptance criteria based on the reported results and typical expectations for such devices. The "reported performance" column directly quotes or summarizes the study findings.

2. Sample Size and Data Provenance:

• Test Set (Clinical Study):
  • Sample Size: 1216 specimens (results summarized, 1228 specimens mentioned for overall prevalence).
  • Data Provenance: Multi-site prospective investigational study. The document states "Three (3) investigational centers participated in the study." The countries of origin are not specified, but the applicant's address is in Quebec, Canada, implying the study might have been conducted there or in the US (given FDA submission).

3. Number of Experts and Qualifications for Ground Truth (Clinical Study):

• The document describes the "Comparative Reference Method" used to establish ground truth for the clinical study. This method involved:
  • Initial analysis on selective chromogenic media.
  • Subculture on Blood Agar (BA) of presumptive S. aureus colonies.
  • Identification confirmed with an agglutination test.
  • Methicillin-resistance confirmed by cefoxitin disk diffusion susceptibility testing.
• Number of Experts/Qualifications: The document does not specify the number or qualifications of experts involved in performing or interpreting these reference method tests. This is a standard microbiology laboratory process, typically performed by trained microbiologists or medical technologists.

4. Adjudication Method for the Test Set:

• The document does not specify an adjudication method for discrepant results between the BD GeneOhm™ MRSA ACP Assay and the Comparative Reference Method. Standard practice often involves a third, more definitive test or expert review in such cases, but it is not mentioned here.

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

• No, an MRMC comparative effectiveness study was not done. This study is a standalone performance evaluation of the device against a reference method. It does not assess human reader performance with or without AI assistance, as it is a molecular diagnostic assay for direct detection of DNA.

6. Standalone Performance Study:

• Yes, a standalone performance study was done. The entire "Performance Data" section (Clinical Performance, Analytical Sensitivity, Analytical Inclusivity, Analytical Specificity, Interfering Substances, Reproducibility, Carry-Over Contamination) describes the algorithm's (BD GeneOhm™ MRSA ACP Assay) performance directly, without human interpretation as part of the evaluated output. The results are automatically generated by the SmartCycler® II software.

7. Type of Ground Truth Used (Clinical Study):

• Culture-based microbiology with confirmatory testing. The ground truth for the clinical study was established by a "Comparative Reference Method" which consisted of:
  • Culture on selective chromogenic media.
  • Subculture on Blood Agar.
  • Agglutination test for S. aureus identification.
  • Cefoxitin disk diffusion susceptibility testing for methicillin resistance. This is considered a gold standard or definitive method for phenotypic MRSA identification in clinical microbiology.

8. Sample Size for the Training Set:

• The document does not mention a training set or its sample size. This is typical for a pre-market submission of a molecular diagnostic assay. These assays are generally designed and validated based on known genetic targets and wet-lab analytical studies rather than machine learning models that require explicit training sets. The development process would involve extensive analytical testing to optimize primers and probes, which is different from training a machine learning algorithm.

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

• As no "training set" in the context of a machine learning algorithm is mentioned, this point is not applicable. The assay's design relies on detecting specific, known MRSA DNA sequences rather than learning from data. The performance is validated against established microbiological methods as described for the clinical and analytical studies.

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