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Melting curve analysis reveals false-positive norovirus detection in a molecular syndromic panel

•Molecular syndromic panels have many advantages and are widely-used.•Understanding the performance characteristics and caveats of molecular panels is crucial.•False-positive norovirus results were commonly detected by a molecular GI panel.•Melting curve review can identify false-positive norovirus...

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Bibliographic Details
Published in:Journal of clinical virology 2024-08, Vol.173, p.105697, Article 105697
Main Authors: Matic, Nancy, Lawson, Tanya, Young, Matthew, Jang, Willson, Bilawka, Jennifer, Gowland, Leah, Ritchie, Gordon, Leung, Victor, Payne, Michael, Stefanovic, Aleksandra, Romney, Marc G., Lowe, Christopher F.
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Language:English
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Summary:•Molecular syndromic panels have many advantages and are widely-used.•Understanding the performance characteristics and caveats of molecular panels is crucial.•False-positive norovirus results were commonly detected by a molecular GI panel.•Melting curve review can identify false-positive norovirus results before reporting. Molecular syndromic panels can improve rapidity of results and ease clinical laboratory workflow, although caution has been raised for potential false-positive results. Upon implementation of a new panel for infectious diarrhea (BioFire® FilmArray® Gastrointestinal [GI] Panel, bioMérieux) in our clinical laboratory, a higher than expected number of stool samples with norovirus were detected. The goal of this study was to investigate positive percent agreement and the false-positive rate of norovirus detected by the multiplex BioFire GI panel compared to a singleplex commercial assay. From October 2023 to January 2024, all prospective stool samples with a positive norovirus result by BioFire had melting curves reviewed manually using the BioFire FilmArray Torch System. Stool samples further underwent testing by a supplementary real-time RT-PCR assay (Xpert® Norovirus, Cepheid) for comparative analysis. Of the 50 stool samples with norovirus detected by BioFire, 18 (36 %) tested negative by Xpert (deemed "false-positives"). Furthermore, melting curve analysis revealed nearly all of these samples had atypical melting curve morphologies for the "Noro-1" target on BioFire (16/18, 89 %), which was statistically significant (Odds Ratio 173.2, 95 % CI [22.2, 5326.9], p < 0.0001). Stool samples with multiple pathogens detected by BioFire including norovirus were not more likely to produce false-positive norovirus results (Odds Ratio 1, 95 % CI [0.3, 3.3], p = 1). Although not described in the manufacturer's Instructions for Use, we propose routine manual review of melting curves for the BioFire GI panel prior to reporting, to mitigate potential false-positive norovirus results.
ISSN:1386-6532
1873-5967
1873-5967
DOI:10.1016/j.jcv.2024.105697