Research Note: Validation of a new differentiation approach using the commercial ASAPTM media to detect the Salmonella 441/014 vaccine strain

Vaccination is one of the most important control tools to reduce Salmonella in poultry production. In order for a live vaccine to be licensed for field use it should be provided with the detection methods to differentiate it from field strains. This paper aims to describe the validation of an alternative method for the differentiation of the Salmonella 441/014 vaccine strain from field strains, using a chromogenic Media, ASAP from bioMérieux. The ASAP-based differentiation method was compared with already authorized methods, namely the Anicon SE Kylt PCR DIVA 1 assay and Ceva S-Check Salmonella differentiation kit, following the ISO 16140-6:2019 validation method guidelines. A Generalised Linear Model was fitted to the data to determine the inclusivity and exclusivity of differentiation methods (PCR Kylt vs. S-Check vs. ASAPTM). Statistical differences were based on a P-value level of < 0.05 (SPSS Inc., Chicago, IL). In this study, we show that the ASAP media was able to differentiate Salmonella Enteritidis vaccine strains from field strains, obtaining 100% agreement between the three differentiation assays. This differentiation approach is quicker, easier to deploy and cheaper as compared to alternative methods.