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Sofia 2 Campylobacter FIA employs immunofluorescence for the rapid qualitative detection of a Campylobacter-specific antigen in human fecal specimens. Sofia 2 Campylobacter FIA is designed to detect C. jejuni, C. coli, C. lari and C. upsalients with signs and symptoms of gastroenteritis. The test is intended for use with preserved fecal specimens in transport media and unpreserved fecal specimens. Test results should be considered in conjunction with clinical findings and patient history.

The Sofia 2 Campylobacter FIA employs immunofluorescence technology that is used with Sofia 2 for the rapid qualitative detection of Campylobacter jejuni, Campylobacter lari, and Campylobacter upsaliensis specific antigens in fecal samples.

The patient's sample is placed in the Specimen Tube containing the Specimen Solution to dilute, making the antigenic components more accessible to the specific antibodies. An aliquot of the diluted sample is dispensed through a filter to remove particulates, making them more compatible for testing, into the Test Cassette sample well. From the sample well, the sample migrates through a test strip containing various unique chemical environments. If Campylobacter jejuni, Campylobacter coli, Campylobacter lari, or Campylobacter upsaliensis specific antigens are present, they will be bound by antibodies coupled to fluorescent microparticles that migrate through the test strip. The fluorescent microparticles containing bound proteins will be captured by antibodies at a defined location on the test strip where they are detected by Sofia 2. If Campylobacter jejuni, Campylobacter coli, Campylobacter lari, or Campylobacter upsaliensis specific antigens are not present, the fluorescent microparticles will not be trapped by the capture antibodies nor detected by Sofia 2.

The Test Cassette is placed inside of Sofia 2 for automatically timed development (WALK AWAY Mode), or pre-incubated on the bench top prior to loading into Sofia 2 (READ NOW Mode), where Sofia 2 will scan, measure, and interpret the immunofluorescent signal using method-specific algorithms. Sofia 2 will display the test results (Positive, Negative, or Invalid) on the screen.

The fluorescence signal obtained with this assay is invisible to the unaided eye. The test results can only be obtained with the proper use of Sofia 2.

The Sofia 2 Campylobacter FIA is a device for the rapid qualitative detection of Campylobacter-specific antigens. It is designed to detect C. jejuni, C. coli, C. lari, and C. upsaliensis from patients with signs and symptoms of gastroenteritis in human fecal specimens (preserved or unpreserved).

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

1. Table of Acceptance Criteria and Reported Device Performance

Based on the provided information, the key performance metrics are Sensitivity and Specificity from the Prospective Clinical Study.

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

• Test Set Sample Size for Clinical Study: 811 total specimens.
  • 191 fresh, neat specimens
  • 620 fresh specimens in transport media
• Data Provenance: Prospective Clinical Study (likely multi-center, though specific countries are not mentioned). All specimens were "fresh".
• Test Set Sample Size for Archived Study: 70 frozen, characterized specimens.
  • 35 culture-negative specimens preserved in transport media.
  • 35 positive specimens (11 in transport media, 24 neat fecal specimens).
• Data Provenance for Archived Study: Archived, frozen specimens, characterized at a central laboratory.

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 for establishing the ground truth.

4. Adjudication method for the test set

• For the Prospective Clinical Study: The primary comparison was against culture and identification. For discordant specimens (Sofia Positive/Culture Negative), species-specific RT-PCR and bi-directional sequence analysis were used for confirmation. In this case, 6 discordant specimens were identified as positive for Campylobacter (3 C. jejuni, 2 C. upsaliensis, and 1 C. coli) by this additional molecular testing. This suggests a form of discordant analysis/adjudication.
• For the Archived Clinical Study: Ground truth was established by culture and further characterized by RT-PCR and bi-directional sequencing. All 35 positive specimens were confirmed by all methods, and all 35 negative specimens yielded 100% correlation with all test methods.

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

This is not applicable as the Sofia 2 Campylobacter FIA is an automated IVD device. It does not involve human readers interpreting results with or without AI assistance in the context of diagnostic imaging, for example. The Sofia 2 instrument scans, measures, and interprets the immunofluorescent signal using method-specific algorithms and displays the result.

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

Yes, the device operates in a standalone manner. The Sofia 2 instrument itself provides the final "Positive, Negative, or Invalid" result after processing the test cassette. This performance directly reflects the algorithm's output. The performance data (Sensitivity, Specificity) from the clinical studies represents this standalone performance.

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

• Prospective Clinical Study: Culture and identification was the primary reference method. For discordant results (Sofia Positive/Culture Negative), species-specific RT-PCR and bi-directional sequence analysis were used as a confirmatory ground truth.
• Archived Clinical Study: Culture for initial characterization, and further confirmed by RT-PCR and bi-directional sequencing.

8. The sample size for the training set

The document does not explicitly state the sample size used for the training set of the device's algorithms. The provided data focuses on the validation of the finalized device.

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

The document does not provide details on how the ground truth for the training set was established. It focuses on the analytical and clinical validation of the device.

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