Validation of PVT VIABLE® for Detection of Legionella in Potable and Non-Potable Water: AOAC Performance Tested MethodSM 082303

Abstract

Background: Phigenics Validation Test (PVT) VIABLE® (Viability Identification Assay by Legionella Enrichment) is a method to detect viable Legionella bacteria in building water systems.

Objective: To evaluate PVT VIABLE against the ISO 11731:2017 Water Quality-Enumeration of Legionella reference method for the detection of viable Legionella species in potable and non-potable water.

Methods: PVT VIABLE was tested for inclusivity (n = 50 strains of Legionella) and exclusivity (n = 30 non-target strains), robustness, and stability. A multi-laboratory instrument variation study was performed to evaluate the PCR data. The matrix study was performed on potable and non-potable water samples inoculated with Legionella pneumophila at a low (n = 20) and high fractional level (n = 5). Samples were analyzed using the PVT VIABLE and confirmed using ISO 11731:2017.

Results: Statistical analysis showed no difference between PVT VIABLE and ISO 11731:2017 for 100 mL test portions of potable and non-potable water. PVT VIABLE demonstrated high levels of specificity and sensitivity in the inclusivity and exclusivity study. Results of the robustness and stability studies demonstrated the method was sufficiently robust to handle small method changes and met the method claims of stability.

Conclusion: PVT VIABLE allows the end user to obtain presumptive results for viable Legionella spp. contamination of potable and non-potable water in 2-3 days.

Highlights: PVT VIABLE provides viable Legionella results in 2-3 days versus 10-14 days for traditional spread plating. This novel diagnostic tool also differentiates between Legionella pneumophila sg1, Legionella pneumophila sg2-15, and Legionella spp. without the need for additional confirmation steps as outlined in ISO 11731:2017.