Validation of PhageDx™ Salmonella Assay in Raw Ground Turkey and Powdered Infant Formula: AOAC Performance Tested MethodSM 121904.

BACKGROUND The PhageDx™ Salmonella Assay is based on the infection of Salmonella spp. by specific bacteriophages and expression of a luciferase reporter gene. Results are generated in as little as 9.5 h for raw ground turkey and 18.5 h for milk-based powdered infant formula (PIF). OBJECTIVE An AOAC Performance Tested Methods  SM (PTM) study was conducted to validate the PhageDx™ Salmonella Assay for the detection of Salmonella in 25 g raw ground turkey and 100 g Powdered Infant Formula (PIF) test portions. METHODS The performance of the PhageDx™ Salmonella Assay was compared to that of the USDA/FSIS MLG 4.10 for raw ground turkey and FDA/BAM Chapter 5 for PIF. Inclusivity/exclusivity, product consistency and stability, and robustness testing were conducted. RESULTS There was no significant difference between the 25 g raw ground turkey and 100 g PIF PhageDx™ Salmonella Assay and the USDA/FSIS MLG 4.10 and FDA/BAM Chapter 5, respectively. The reporter bacteriophages were specific for Salmonella and infected 108 strains in inclusivity testing. They did not infect 30 non-Salmonella bacteria in exclusivity testing. Robustness testing showed that the method performed well with specific deviations from the standard protocol. Consistency and stability testing demonstrated that the recombinant phage gave consistent results across three production lots and was stable when stored under appropriate conditions for at least six months. CONCLUSIONS AND HIGHLIGHTS The data collected in the validation study demonstrate that the PhageDx™ Salmonella Assay meets the qualifications for PTM status.