Salmonella in swine: Prevalence, multidrug resistance, and vaccination strategies

Authors: Bearson, Shawn

Submitted to: Annual Review of Animal Biosciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/2021
Publication Date: 10/26/2021
Citation: Bearson, S.M. 2021. Salmonella in swine: Prevalence, multidrug resistance, and vaccination strategies. Annual Review of Animal Biosciences. 10:373-393. https://doi.org/10.1146/annurev-animal-013120-043304.
DOI: https://doi.org/10.1146/annurev-animal-013120-043304

Interpretive Summary: The Centers for Disease Control and Prevention (CDC) estimates 1.3 million Salmonella infections and 420 deaths annually in the U.S. with an estimated economic burden of $3.7 billion. The National Outbreak Reporting System (NORS) reported 1,798 outbreaks from 2010-2017, with several of those outbreaks associated with the consumption of food animal products such as turkey, chicken, ground beef, shell eggs, and pork. Pork is the most consumed meat worldwide; thus, optimizing Salmonella control strategies at critical control points along the farm-to-fork pork production chain will offer the greatest success for improving food safety and public health while diminishing the need for product recalls. This review discusses Salmonella prevalence in swine, antimicrobial resistance and metal tolerance in Salmonella, a recent outbreak of Salmonella I 4,[5],12:i:- in pork, and the use of vaccination to reduce Salmonella in swine, thereby reducing environmental and food product contamination.

Technical Abstract: An estimated 1.3 million Salmonella infections and 420 deaths occur annually in the U.S. with an estimated economic burden of $3.7 billion. Over 50% of swine operations test positive for Salmonella in the U.S. (National Animal Health Monitoring System), and 20% of Salmonella from swine are multidrug resistant (MDR; resistant to >3 antimicrobial classes) according to the National Antimicrobial Resistance Monitoring System. The focus of this review on Salmonella in swine addresses the current status of these topic areas by describing antimicrobial resistance and metal tolerance in Salmonella, and the contribution of horizontal gene transfer in the MDR status of Salmonella. A major challenge in controlling Salmonella is that Salmonella is a foodborne pathogen in humans, but is often a commensal in food animals, thereby establishing an asymptomatic reservoir state in food animals, including swine. The need for Salmonella interventions intensifies as food animal production systems continue to expand, yet antimicrobial usage becomes more limiting. Vaccination against Salmonella in swine limits animal, environmental and food contamination.