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The illumigene® Group A Streptococcus (Group A Strep) assay, performed on the illumipro-10™, is a qualitative in vitro diagnostic test for the detection of Streptococcus pyogenes (Group A ß-hemolytic Streptococcus) in throat swab specimens.

The illumigene Group A Strep assay utilizes loop-mediated isothermal DNA amplification (LAMP) technology to detect Streptococcus pyogenes by targeting a segment of the Streptococcus pyogenes genome. Results from the illumigene Group A Strep assay can be used as an aid in the diagnosis of Group A Streptococcal pharyngitis. The assay is not intended to monitor treatment for Group A Streptococcus infections.

illumigene Group A Strep is intended for use in hospital, reference or state laboratory settings. The device is not intended for point of-care use.

The illumigene Molecular Diagnostic Test System is comprised of the illumigene® Group A Strep DNA Amplification Test Kit, the illumigene® Group A Strep External Control Kit and the illumipro-10™ Automated Isothermal Amplification and Detection System.

The illumigene Group A Strep assay utilizes loop-mediated isothermal amplification (LAMP) technology to detect the presence of Streptococcus pyogenes (Group A beta-hemolytic Streptococus) in throat swab specimens. Each illumigene Group A Strep assay is completed using an illumigene Sample Preparation Apparatus II/Negative Control III containing Control material, an illumigene Group A Streptococcus Test Device and an illumigene Heat Treatment Tube. Samples are diluted in the illumigene Sample Preparation Apparatus II and dispensed into an illumigene Heat Treatment Tube. Target and Control DNA is made available for isothermal amplification via heat-treatment. DNA amplification occurs in the illumigene Test Device.

The illumipro- 10heats each illumigene Group A Strep Test Device containing prepared sample and Control material, facilitating amplification of target DNA. When S. pyogenes is present in the throat swab specimen, a 206 base pair sequence of the S. pyogenes genome is amplified and magnesium pyrophosphate is generated. Magnesium pyrophosphate forms a precipitate in the reaction mixture. The absorbance characteristics of the reaction solutions at the assay Run Start (Signalwikal, S) and at the assay Run End (Signalman) S). The illumipro-10 calculates the change in light transmission between Run End and Run Start (S;S;S;) and compares the ratio to a fixed cut-off value for disposition of results.

Fixed cut-off values for the TEST chamber are used to report sample results. TEST chamber Sy:S, ratios less than 82% are reported as 'POSITIVE'; TEST chamber S;S, ratios greater than or equal to 82% are reported as 'NEGATIVE'. Numerical volues ore not reported. Fixed cut-off values for the CONTROL chamber are used to determine validity. CONTROL chamber S;:S, ratios less than 90% are considered valid and allow for reporting of TEST chamber results (POSITIVE, NEGATIVE). CONTROL chamber SyS, ratios greater than or equal to 90% are considered invalid and prevent reporting of TEST chamber results. Invalid CONTROL chamber reactions are reported as 'NVALID'. Numerical values are not reported. More stringent cut-off criteria are applied to the CONTROL chamber reaction to ensure amplification is not inhibited, reagents are performing as intended and that sample processing was performed appropriately.

The illumigene Group A Strep External Control Kit contains a Positive Control Reagent. The External Positive control Reagent is used in conjunction with the illumigene Sample Preparation Apparatus II/Negative Control III reagent included in the illumigene Group A Strep Kit as part of routine Quality Control testing. External Control reagents are provided to aid the user in detection of reagent deterioration, adverse environmental or test conditions, or variance in operator performance that may lead to test errors.

Here's a breakdown of the acceptance criteria and the study that proves the device meets them, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

Note: The document does not explicitly state numerical acceptance criteria for sensitivity, specificity, or invalid rate. These are inferred from the aim of demonstrating substantial equivalence and the high performance values reported for a diagnostic test.

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

• Sample Size for Test Set: A total of 798 qualified specimens were evaluated in the clinical study.
• Data Provenance: The specimens were retrospective, as they were "leftover human specimens, not individually identifiable" and "submitted to the testing laboratory by an ordering physician for Group A Streptococcus testing." They were collected from patients presumed to be symptomatic.
• Country of Origin: The clinical trials were conducted at "Three independent clinical test sites located in the Midwestern and Southern regions of the United States."

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

The document does not explicitly state the number or qualifications of "experts" in the traditional sense of radiologists or pathologists for establishing ground truth. Instead, the ground truth for the clinical study was established using a Composite Culture Method. This method involved:

• The Clinical Site Culture Method as performed in standard of care testing.
• A Reference Culture Method performed by Meridian Bioscience.

Specimens were considered positive if they produced positive Group A Streptococcus results from either the Site Culture Method or the Reference Culture Method. This implies that the 'experts' in this context are the laboratory personnel performing and interpreting the bacterial cultures at the clinical sites and Meridian Bioscience, following established microbiological protocols. No specific years of experience or board certifications are mentioned for these personnel.

4. Adjudication Method for the Test Set

The adjudication method used for establishing the ground truth was a "Composite Culture Method." This is a form of 2-method consensus, where a specimen was deemed positive if either the clinical site culture or the reference culture showed positive results. If both were negative, the specimen was considered negative.

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

No, an MRMC comparative effectiveness study involving human readers with and without AI assistance was not done. This study focuses on the standalone performance of the illumigene® Group A Streptococcus assay, which is a molecular diagnostic test, not an image-based AI system requiring human interpretation.

6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study

Yes, a standalone performance study was conducted. The illumigene® Group A Streptococcus assay is a qualitative in vitro diagnostic test, and its performance characteristics (sensitivity, specificity, invalid rate) were determined solely by comparing its results to the Composite Culture Method, without any human interpretation of the device's output influencing the reported performance metrics. The illumipro-10™ automated system reports results as 'POSITIVE', 'NEGATIVE', or 'INVALID' based on fixed cut-off values.

7. Type of Ground Truth Used

The type of ground truth used for the clinical study was Composite Bacterial Culture. This involved both a clinical site culture and a reference culture to determine the presence or absence of Streptococcus pyogenes.

8. Sample Size for the Training Set

The document does not explicitly state the sample size for a training set. The language suggests that the fixed cut-off values for the assay were "based on well characterized clinical specimens." However, a distinct "training set" with separate sample size numbers is not provided. The clinical study (test set) involved 798 qualified specimens.

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

As mentioned above, the document states that the "Fixed cut-off values were based on well characterized clinical specimens." It does not provide detailed information on how the ground truth for these specific specimens (which implicitly served a role similar to a training/development set for establishing cut-offs) was established. It is reasonable to assume it would likely also involve bacterial culture methods, similar to the test set, but this is not explicitly detailed for the cut-off establishment process.

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