Study validates disc diffusion method to distinguish Salmonella vaccine strains

A new paper in Veterinary Sciences reports that researchers validated a simple disc diffusion method to reliably distinguish a bivalent live Salmonella poultry vaccine from field strains across multiple suppliers. The study focuses on vaccine-related differentiation for Salmonella Enteritidis and Salmonella Typhimurium, two serovars that remain central to poultry food safety and public health. That matters because live vaccines are widely used in breeders and layers, but positive flock samples can create major operational consequences if labs can't tell vaccine strains from true field infections. EU rules have long required that live poultry Salmonella vaccines come with a method to distinguish vaccine from wild-type strains. (eur-lex.europa.eu)

Why it matters: For veterinary diagnosticians, poultry veterinarians, and food animal practices supporting layer and breeder operations, the practical issue is surveillance confidence. A validated, lower-complexity phenotypic method could help labs avoid misclassifying vaccine detections as outbreak strains, while preserving the value of live vaccination programs used to reduce shedding and support Salmonella control. The broader backdrop is still significant: EFSA says salmonellosis remains one of the most frequently reported zoonoses in Europe, with poultry and eggs continuing to be important sources. (efsa.europa.eu)

What to watch: Watch for whether reference and commercial labs adopt the method, and whether regulators or vaccine suppliers position it as a standard alternative to PCR-based DIVA workflows. (mdpi.com)