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IDI-MRSA™ assay is a qualitative in vitro diagnostic test for the direct detection of nasal colonization by methicillin-resistant Staphylococcus aureus (MRSA) to aid in the prevention and control of MRSA infections in healthcare settings. The test performed on the Smart Cycler® instrument with a nasal swab specimen from patients at risk for colonization, utilizes polymerase chain reaction (PCR) for the amplification of MRSA DNA and fluorogenic target-specific hybridization probes for the detection of the amplified DNA.

IDI-MRSA is not intended to diagnose MRSA infections nor to guide or monitor treatment for Concomitant cultures are necessary only to recover organisms for MRSA infections. epidemiological typing or for further susceptibility testing.

A nasal specimen is collected and transported to the laboratory using the Copan Venturi Transystem®. For testing, the swab is placed in sample preparation buffer. The specimen is concentrated and lysed. An aliquot of the lysate is added to PCR reagents which contain the MRSA-specific primers used to amplify the genetic target [a sequence near the insertion site of Staphylococcal Cassette Chromosome mec (SCCmec)], if present. The assay also includes an internal control (IC) used to detect PCR inhibitory specimens and to confirm the integrity of assay reagents in negative specimens. Amplified targets are detected with hybridization probes labeled with quenched fluorophores (molecular beacons). The amplification, the detection of fluorescence and the interpretation of signals are done automatically by the Smart Cycler® instrument. The whole processed takes about 60 to 75 minutes, depending on the number of specimens processed. This is in addition to specimen preparation which takes about 15 minutes. If appropriate, culture media can be inoculated during specimen preparation or up to 24 hours after its preparation.

Here's a breakdown of the acceptance criteria and study information for the Infectio Diagnostic Inc. IDI-MRSA™ assay, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

The submission describes a Special 510(k) for modifications to an already cleared device. Therefore, the "acceptance criteria" are primarily established against the performance of the original, cleared formulation of the IDI-MRSA™ assay. The reported device performance indicates equivalence to the original.

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

The document does not explicitly state the specific sample size used for the test set of clinical specimens. It only mentions "Performance with clinical specimens" and provides results for sensitivity, specificity, unresolved specimens, and agreement with the original formulation.

The data provenance is not explicitly stated regarding country of origin or whether it was retrospective or prospective. However, given it's a Special 510(k) for modifications, it's highly probable the clinical specimen testing involved comparing the modified assay's performance against the original assay on a set of existing (retrospective) and/or newly collected (prospective) clinical samples.

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

This information is not provided in the document. For an in vitro diagnostic test like this, the "ground truth" for clinical specimens would typically be established by established microbiological culture methods, often interpreted by clinical microbiologists or infectious disease specialists. However, the document does not detail this process or the number/qualifications of experts involved.

4. Adjudication Method for the Test Set

This information is not provided in the document. Given the nature of a PCR-based assay, adjudication for "ground truth" in the context of clinical specimens usually involves standard microbiological culture results, not expert consensus on the device's output itself.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance

A Multi-Reader Multi-Case (MRMC) comparative effectiveness study is not applicable to this device. The IDI-MRSA™ assay is a standalone in vitro diagnostic test that provides a qualitative result (detection of MRSA DNA). There is no "human reader" interpreting the output in the same way as, for example, a radiologist interprets an imaging scan. Therefore, there's no concept of human readers improving with or without "AI assistance" in this context.

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

Yes, a standalone performance study was implicitly done. The IDI-MRSA™ assay is a fully automated system from detection of fluorescence to interpretation of signals by the Smart Cycler® instrument. The comparison study evaluated the modified assay's direct output (detection of MRSA DNA) against the original formulation. The assay itself performs the "algorithm" for positive/negative determination.

7. The Type of Ground Truth Used

For the "Performance with clinical specimens," the ground truth is implicitly microbiological culture results, which is considered the gold standard for detecting Staphylococcus aureus and determining methicillin resistance. The document states: "Concomitant cultures are necessary only to recover organisms for epidemiological typing or for further susceptibility testing," which suggests culture is the comparator, though not explicitly called the "ground truth" for the performance metrics.

8. The Sample Size for the Training Set

The document does not specify a separate "training set" or its sample size. For an IVD like this, analytical validation and optimization might involve various bacterial strains and spiked samples (which could be considered part of a development/training phase), but a distinct "training set" in the machine learning sense is not described. The studies primarily focus on validating the modified assay against the original cleared assay's performance characteristics.

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

As no explicit "training set" is described, the method for establishing its ground truth is not provided. However, for analytical parameters like Limit of Detection, Analytical Sensitivity, and Specificity, the ground truth would be established by carefully characterized bacterial isolates, known concentrations of target DNA, and well-identified non-target organisms.

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IDI-MRSA™ assay is a qualitative in vitro diagnostic test for the direct detection of nasal colonization by methicillin-resistant Staphylococcus aureus (MRSA) to aid in the prevention and control of MRSA infections in healthcare settings. The test performed on the Smart Cycler® instrument with a nasal swab specimen from patients at risk for colonization, utilizes polymerase chain reaction (PCR) for the amplification of MRSA DNA and fluorogenic target-specific hybridization probes for the detection of the amplified DNA.

IDI-MRSA is not intended to diagnose MRSA infections nor to guide or monitor treatment for Concomitant cultures are necessary only to recover organisms for MRSA infections. epidemiological typing or for further susceptibility testing.

IDI-MRSA™ assay is a qualitative in vitro diagnostic test for the direct detection of nasal colonization by methicillin-resistant Staphylococcus aureus (MRSA). A nasal specimen is collected and transported to the laboratory using the Copan Venturi Transystem®. For testing, the swab is placed in sample preparation buffer. The specimen is concentrated and lysed. An aliquot of the lysate is added to PCR reagents which contain the MRSA-specific primers used to amplify the genetic target [a sequence near the insertion site of Staphylococcal Cassette Chromosome mec (SCCmec)], if present. The assay also includes an internal control (IC) used to detect PCR inhibitory specimens and to confirm the integrity of an internal of the PC (C is a DNA fragment of 335-bp including a 277-bp assay reagents in hogative optionnel to targets are detected with hybridization probes labeled sequence fluorophores (rnolecular beacons). For the detection of MRSA amplicons, the with quencher beacon contains the fluorophore 5-carboxyfluorescein (amine reactive ester of molocally beader commonly called FAM) at the 5' end and the non-fluorescent quencher carboxy-liderooooin bonneeriy on the opposite end of the oligonucleotide. For the detection moley daboy onlorido (1) (1) (1) (1) (1) (1) (1) (1) (1) (1) (1) (1) (1) (1) (1) (1) (1) (1) (1) (1) ( fluorescein (TET) at the 5' end and the non-fluorescent quencher moiety DABCYL at the 3' end. The test is performed on the Smart Cycler® instrument which monitors simultaneously the fluorescence emitted by each beacon, interprets all data and at the end of the cycling program provides a final result.

1. Table of Acceptance Criteria and Reported Device Performance:

Note: The document does not explicitly state "acceptance criteria." The criteria listed above are inferred from the performance metrics presented in the clinical study results and are typical for diagnostic device submissions.

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

• Sample Size: 786 nasal swab specimens.
• Data Provenance: The data was collected as part of a multi-center study. The specific countries are not mentioned, but the submitting company is based in Canada. The study was prospective in nature, as indicated by the collection of specimens for the study.

3. Number of Experts and Qualifications for Ground Truth Establishment (Test Set):

• The document does not specify the number of individual experts or their qualifications (e.g., radiologists with X years of experience) used to establish the ground truth.
• Instead, the ground truth was established using a "reference method" which consisted of a culture-based approach. This method involved:
  • Initial analysis with oxacillin screen agar (OxaMSA) after selective growth on mannitol salt agar.
  • For specimens negative by OxaMSA, an additional analysis included an enrichment step in trypticase soy broth (OxaTSB) followed by oxacillin screen agar test.
• An MRSA-positive specimen was defined as positive by either culture technique, and an MRSA-negative specimen was negative by both.
• Further investigation was conducted for discrepant results where IDI-MRSA was positive but culture-negative, which involved "more enhanced culture techniques" (details not provided) and mecA-specific PCR of isolates. This implies expert judgment and advanced laboratory techniques were involved in clarifying these specific cases.

4. Adjudication Method for the Test Set:

• The document does not describe a traditional "adjudication method" involving multiple human readers for interpreting the ground truth.
• The ground truth was established by a defined laboratory methodology (culture techniques) which inherently serves as a reference standard.
• For discrepant results (IDI-MRSA positive, culture negative), "further investigation" was conducted, leading to a reclassification of some specimens. This suggests a form of expert review for these specific cases, but not a full-scale multi-reader adjudication process.

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

• No, a multi-reader multi-case (MRMC) comparative effectiveness study was not performed.
• This study evaluates a diagnostic assay (IDI-MRSA™ assay) against a laboratory reference standard (culture method), not the improvement of human readers with AI assistance.

6. Standalone Performance Study:

• Yes, a standalone performance study was done. The entire "Clinical Performance" section describes the performance of the IDI-MRSA™ assay on its own, directly comparing its results to the established culture reference method. The reported sensitivity, specificity, positive predictive value, and negative predictive value are all measures of the algorithm's standalone performance.

7. Type of Ground Truth Used:

• The primary ground truth used was expert consensus pathology/culture results. This involved a multi-step culture-based reference method (oxacillin screen agar, enrichment in trypticase soy broth, and follow-up mecA-specific PCR for discrepant results).

8. Sample Size for the Training Set:

• The document does not explicitly state the sample size for a training set. The study described is a clinical performance study using a test set of 786 specimens.
• As this is a molecular diagnostic assay (PCR-based), it is likely that the "training" (development and optimization) would have involved laboratory experiments with characterized strains and clinical samples, but a formal clinical "training set" in the context of machine learning is not applicable or described here.

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

• Since a formal "training set" is not explicitly mentioned or applicable in the context of this analytical device, the method for establishing ground truth for such a set is not described.
• Presumably, the development of the assay (including primer and probe design) would have been based on known MRSA strains with established genetic characteristics (e.g., presence of SCCmec and mecA gene), and preliminary testing would have involved well-characterized clinical isolates and control samples with confirmed MRSA status via standard microbiological and genetic methods.

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