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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Food Safety and Enteric Pathogens Research » Research » Publications at this Location » Publication #401690
Research Project: Analysis of Genetic Factors that Increase Foodborne Pathogen Fitness, Virulence, and Antimicrobial Resistance Transfer, to Identify Interventions against Salmonella and Campylobacter in Food Animals

Location: Food Safety and Enteric Pathogens Research

Title: Genomic and phenotypic characterization of turkey outbreak-associated Salmonella enterica serovar reading

Author
item Bearson, Shawn
item SIVASANKARAN, SATHESH - Iowa State University
item Bearson, Bradley - Brad
item Trachsel, Julian

Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: 3/19/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Poultry and their products are a common source of Salmonella-associated foodborne illness, and an estimated 17% of human illnesses are attributed to turkey products. From November 2017 to March 2019, a turkey-associated outbreak of Salmonella enterica serovar Reading (S. Reading) was linked to 358 human infections in 42 U.S. states and Canada. Because S. Reading was seldom linked to human illness prior to this outbreak, the current study compared genomic sequences of S. Reading isolates prior to the outbreak (pre-outbreak) to strains isolated during the outbreak period, focusing on genes that were different between the two outbreak groups but common within a group. Following whole genome sequence analysis of five pre-outbreak and five outbreak turkey isolates of S. Reading, 37 genes located within two distinct chromosomal regions were present only in the pre-outbreak isolates: 1) an ~5 kb region containing 4 protein-coding genes including uidA which encodes beta-glucuronidase, pgdA encoding peptidoglycan deacetylase, and two hypothetical proteins as well as 2) an ~28 kb region comprised of 32 phage-like genes and the xerC gene which encodes tyrosine recombinase (frequently associated with phage genes). Another genetic difference detected in the five outbreak isolates was a deletional event introducing a premature stop codon within the cirA gene, which encodes a colicin Ia/b receptor. Occurrence of the identified genetic differences were examined in 75 S. Reading human isolates. Of the 36 S. Reading isolates collected before/in 2017, 83% (30/36) and 94% (34/36) of the isolates contained the uidA and pgdA genes, respectively, but only 28% (11/39) of the isolates collected after 2017 harbored the uidA and pgdA genes (uidA P = 8.55E-06 and pgdA P = 3.29E-06). A similar result was observed in comparing the cirA gene; truncation of the CirA protein was significantly higher (P = 3.98E-06) in isolates collected after 2017 compared to before/in 2017. Phenotypic analysis of the S. Reading isolates for colicin sensitivity (CirA) and ß-methyl-D-glucuronic acid utilization (UidA and accessory proteins) supported the genomic data. Overall, a similar genome reduction pattern was generally observed in both the turkey and human isolates of S. Reading during the outbreak period, and the genetic differences were present in genes that could potentially contribute to variation in Salmonella colonization, fitness or virulence.