Kogene PowerChek Multiplex Real-time PCR Kits Versus the BioFire FilmArray Gastrointestinal Panel: Roles of Crossing Point Values and Melting Curves in Interpreting the FilmArray Gastrointestinal Panel

Abstract

Background: Various molecular methods are used to rapidly detect gastrointestinal patho- gens, highlighting the importance of understanding the performance of the associated kits in detail. We comprehensively assessed the performance of Kogene PowerChek multiplex real-time PCR kits (PowerChek Bacterial/Viral Kits) with the FilmArray GI Panel. Methods: Residual stool specimens (N=246), initially tested utilizing the FilmArray GI Panel (May 2023–Jan 2024), were reanalyzed using PowerChek Bacterial/Viral Kits. Dis- crepancies were resolved by performing additional molecular assays and reviewing culture results when available. True positives (TPs)/true negatives were defined by concordant re- sults in at least two assays. We determined cycle threshold (Ct)/crossing point (Cp) distri- butions between the TP and false positive (FP) groups and analyzed melting curves for the FilmArray GI Panel FPs. Results: The positive-percent agreement (PPA) of the PowerChek Bacterial/Viral Kits was 50–100%, with lower values for Salmonella spp., rotavirus, and astrovirus, whereas the Fil- mArray GI Panel showed 100% PPA across all targets. Both platforms demonstrated >99% negative-percent agreement, except for enteropathogenic Escherichia coli (EPEC) and ade- novirus (PowerChek Bacterial/Viral Kits) or EPEC, enteroaggregative E. coli, norovirus, and Salmonella spp. (FilmArray GI Panel). The FPs showed higher Ct/Cp values with both kits, and these values were significantly higher for adenovirus (PowerChek Viral Kit), EPEC, and norovirus (FilmArray GI Panel). Melting curve analysis of four norovirus FPs (FilmArray GI Panel) revealed atypical patterns in three cases. Conclusions: The FilmArray GI Panel demonstrated higher sensitivity than the PowerChek Kits. For norovirus, melting curve analysis will help avoid FPs.