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United States Department of Agriculture

Agricultural Research Service

Research Project: Genetic Analysis of Poultry-Associated Salmonella enterica to Identify and Characterize Properties and Markers Associated with Egg-Borne Transmission of Illness

Location: Egg Safety and Quality

Title: Development and application of novel SNP-based serotyping assays in targeting Salmonella enterica within the poultry production and processing continuum.

Authors
item Rothrock, Michael
item Guard, Jean
item Gast, Richard

Submitted to: International Association for Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: March 5, 2014
Publication Date: N/A

Technical Abstract: Salmonella enterica subsp. enterica serotype Enteriditis (S. Enteriditis) is the leading cause of salmonellosis worldwide. While some S. enterica serotypes are specific to birds, many represent human zoonotic pathogens, thus their presence and survival throughout the continuum of poultry production environments is of vital concern to the poultry industry. Purpose: It is essential to rapidly type the various Salmonella to determine potential food safety-related issues, especially those that occur within the serotypes linked to disease. A novel approach to molecular serotyping of poultry-related Salmonella would be to type them based on single nucleotide polymorphisms (SNPs) within the genetic code of these diverse serotypes. Methods: Primers were designed to target ~ 300-bp regions of both a virulence-associated (cyaA) and non virulence (ushA) genes that contained descriptive SNPs for 4–5 serotypes (3 Enteriditis, Typhi, Typhimurim, Heidelberg, Fetus and Kentucky). Hybridization probes targeted these descriptive SNPs and Luminex MagPlex hybridization protocols were developed and optimized. Both assays were validated using strains recovered from environmental samples from throughout the production continuum. Results: Both assays were found to be highly specific and sensitive towards their respective SNP targets, even when testing samples containing all target SNPs for a given assay. For most environmental isolates tested, the assays were able to effectively pathotype different S. Enteriditis strains and serotype different S. enterica, as well as quickly differentiating between Kentucky and Enteriditis recovered as part of a poultry challenge study. Significance: These data highlight the potential of SNP-based assays to rapidly serotype poultry-related Salmonella enterica. Expanding this method to include other serotype-specific SNPs not already targeted by our current assays, or applying it directly to isolates recovered from challenge studies will allow us to not only rapidly determine which Salmonella are recovered, but also which environmental parameters control the survival of the serotypes within different poultry models.

Last Modified: 8/27/2014
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