Analytical equivalence study of LiquidArray® Gastrointestinal Kit with extraction performed on GenoXtract®

Background: LiquidArray® Gastrointestinal VER 1.0 Kit is a rapid, sensitive, highly multiplexed PCR workflow to detect the most relevant bacterial, viral, parasitic and pathogen associated toxins which cause gastroenteritis and based on next generation LiquidArray® technology. The assay has been fully developed, having completed all design and development phases, including a comprehensive analytical and clinical study at a Public Health Wales clinical laboratory in the UK with extraction performed on GenoXtract® fleXT. An analytical equivalence study was performed using the GenoXtract® for extraction with the NA Extraction kit.

Materials/methods: Human stool samples were extracted from a Stool Stabilization Buffer using the GenoXtract®, an automated sample processor for the extraction of 12 samples per run. The PCR analysis was carried out using a FluoroCycler® XT, a thermal cycler platform specific to LiquidArray technology. The PCR is carried out over two reaction wells to achieve the high-level coverage of all pathogens. 200 samples were assessed in the study, using prospectively collected samples as well as some archived patient specimens, and enrolled under predefined inclusion and exclusion criteria. The test was compared to other CE-IVD multiplex PCR tests to enable coverage of all pathogens detected via LiquidArray Gastrointestinal.

Results: Excellent sensitivity was achieved across both PCR1 and PCR2 targets with all detected targets showing performance >95% when tested at LOD. The overall detection rates between the GenoXtract® and the GenoXtract® fleXT resulted as 97.5 % correct for the 200 clinical samples tested.

Summary: The clinical sensitivity and specificity values reported throughout the study provide evidence of clinical performance when compared to similar technologies. The assay exhibits increased pathogen coverage when compared to some current clinical diagnostics, with the ability to detect and differentiate bacterial, viral and parasitic targets. Excellent useability was demonstrated, with very low rates of invalid and indeterminate results reported. The two-well PCR workflow offers increased throughput in diagnostic capability.