In this context, diagnostic mainly refers to the isolation of field Salmonella strains and their differentiation from the vaccine strains. A National Salmonella Surveillance System is based on data collected by state and territorial public health laboratories and authorized private laboratories. In the EU, official monitoring and self-monitoring are performed in all industrial flocks of breeders, layers, broilers, and turkeys depending on the type of production (meat, table eggs or hatching eggs). Self-monitoring consists of regular microbiological tests to determine Salmonella; it enables positive flocks to be detected, the prevalence to be assessed and corrective actions to be taken (Mueller-Doblies, 2015). The regulation EN/ISO 6579 international standard Amend. 1 Annex D, establishes that vaccine strains need to be differentiated from field strains; it describes also the method for the detection of Salmonella spp. in feces and other samples from primary production and constitutes the reference method for Salmonella related criteria (ISO 6579 procedure).