Search Results

Adenovirus R-gene® US Assay is a Real Time PCR in vitro diagnostic test for the rapid and qualitative detection of Adenovirus viral DNA isolated and purified from nasopharyngeal swab or nasopharyngeal wash/aspirate specimens obtained from individuals exhibiting signs and symptoms of acute respiratory infection. The intended use for this test is to aid in the diagnosis of respiratory Adenovirus infection in humans in conjunction with other clinical and laboratory findings. The test detects, but does not differentiate, Adenovirus species (A, B, C, D, E, F and G). Negative results do not preclude Adenovirus infection and should not be used as the sole basis for treatment or other patient management decisions.

The ADENOVIRUS R-gene® US Assay is a Taqman based Real Time PCR Assay that enables detection of human Adenovirus DNA and Internal Control 2. An overview of the procedure is as follows: 1. Collect nasopharyngeal specimens from symptomatic patients. Two transport media may be used UTM or M4RT (not provided with kit). 2. Add an Internal Control 2 (IC2) to every sample and to the W0 reagent, to monitor for inhibitors present in the specimens and check the extraction step. 3. Perform extraction and purification of nucleic acids using a NucliSENS® easyMAG™ System (bioMérieux) and the Automated Magnetic Extraction Reagents (bioMérieux). 4. Add purified nucleic acids to the ready to use R10 amplification premix included in the ADENOVIRUS R-gene® US kit. The R10 amplification premix contains oligonucleotide primers and target-specific oligonucleotide probes. The primers and probes are complementary to a fragment located in the Hexon gene region and to the internal control 2 DNA sequence. The probes are duallabeled with a reporter dye attached to the 5'-end and a quencher dye attached to the 3'-end. 5. Perform amplification of DNA in a Cepheid SmartCycler® 2.0 instrument. In this process, the probe anneals specifically to the DNA template followed by primer extension and amplification. The 5' - 3' exonuclease activity of the Tag polymerase cleaves the probe separating the reporter dye from the quencher. This generates an increase in fluorescent signal upon excitation from a light source. With each cycle, additional reporter dye molecules are cleaved from their respective probes, further increasing fluorescent signal. The amount of fluorescence at any given cycle is dependent on the amount of amplification products present at that time. Fluorescent intensity is monitored during each PCR cycle by the real-time instrument. 6. Interpretation.

Acceptance Criteria and Study for Adenovirus R-gene® US Assay

Here's a breakdown of the acceptance criteria and study details for the Adenovirus R-gene® US Assay based on the provided 510(k) summary:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are not explicitly stated as clear pass/fail thresholds in the provided document, but rather implied through the presentation of performance studies. The reported device performance is presented as sensitivity and specificity values against a reference method.

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

• Test Set Sample Size:

  • Clinical Study: 1576 samples (1183 swab specimens, 393 NP wash/aspirate specimens).
  • LoD Study: 4 to 6 dilutions for each of the 22 Adenovirus types tested, for a total of 60 to 90 amplifications/detections.
  • Analytical Specificity: Panels of 61 potentially cross-reacting microorganisms.
  • Carry-Over/Cross-Contamination: 55 High Positive and 55 Negative samples over 5 extraction runs and 4 amplification runs.
  • Precision (Within-Laboratory): 150 Moderate Positive, 120 Low Positive, 90 High Negative total replicates.
  • Precision (Between-Laboratory): 450 Moderate Positive, 360 Low Positive, 270 High Negative total replicates across 3 sites.
  • Cut-off Determination: 218 negative and high negative samples; 184 clinical samples (preliminary study, France); 1576 clinical samples (US clinical studies).

• Data Provenance:

  • Clinical Study: Multi-center prospective investigational study conducted across 3 geographically diverse institutions in the US.
  • Preliminary Cut-off Study: Performed at Caen Hospital (France).
  • Analytical, Carry-over, Interference, and Within-Laboratory Precision studies: Performed at bioMérieux SA – ARGENE site (France).
  • Between-Laboratory Precision: Performed at 3 external sites in the US.
  • The document implies the data is mostly prospective for the clinical evaluation, as it describes a multi-center investigational study with samples collected from September 2010 - November 2011.

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

The document does not specify the number or qualifications of experts used to establish the ground truth for the test set.

4. Adjudication Method for the Test Set

The primary reference method used for the clinical study was "rapid culture (shell vial) followed by direct fluorescent antibody (DFA) screening and identification" using the D3Ultra™ DFA Respiratory Virus screening & ID kit from Diagnostic Hybrids (DHI).

For discrepant results, a "confirmed as positive for adenovirus using Real Time PCR" method was noted, implying an additional confirmatory PCR outside of the device being evaluated. The details of this confirmatory PCR (e.g., specific assay, blinding, adjudication process) are not provided.

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 performed. The study described compares the performance of the Adenovirus R-gene® US Assay (an automated test) against a reference laboratory method (culture + DFA), not against human readers with and without AI assistance.

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

Yes, the studies described are for the standalone performance of the Adenovirus R-gene® US Assay. This is an in vitro diagnostic (IVD) test, where the "algorithm" (the PCR assay and associated interpretation rules) operates independently to generate a result. There is no human interaction with an AI component for interpretation as would be the case in an imaging diagnostic AI device.

7. The Type of Ground Truth Used

The primary ground truth for the clinical studies was viral culture followed by direct fluorescent antibody (DFA) staining. For discrepant results from this primary method, "Real Time PCR" was used as a confirmatory method, which can be considered a form of expert consensus if adjudicated by laboratory experts, or a higher-sensitivity reference method. For the Limit of Detection (LoD), titered viral strains (TCID50/mL) and quantified plasmids (copies/mL) were used.

8. The Sample Size for the Training Set

The document does not explicitly state a separate "training set" size for the clinical performance evaluation. For IVD devices, analytical studies (LoD, specificity, interference, precision) often contribute to the development and optimization of the assay itself, which can be seen as an iterative "training" process for the assay's design and interpretation rules (e.g., cut-off determination). The document mentions "preliminary study, performed at Caen Hospital (France), on 184 clinical samples, prior to US clinical studies" for cut-off determination, which could be considered part of the development/training phase for establishing the assay's parameters.

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

For the preliminary cut-off study using 184 clinical samples at Caen Hospital (France), the method for establishing ground truth is not explicitly detailed. However, given the context of molecular assays, it would likely have involved an established laboratory reference method for Adenovirus detection, similar to or the same as the one used for the main clinical study (culture + DFA or another validated PCR). For the analytical studies, the ground truth was established by using well-characterized and quantified viral strains or plasmids with known concentrations.

Ask a specific question about this device