<i>Salmonella</i>in Swine: Prevalence, Multidrug Resistance, and Vaccination Strategies

Abstract

An estimated 1.3 million <i>Salmonella</i> infections and 420 deaths occur annually in the United States, with an estimated economic burden of $3.7 billion. More than 50% of US swine operations test positive for <i>Salmonella</i> according to the National Animal Health Monitoring System, and 20% of <i>Salmonella</i> from swine are multidrug resistant (resistant to ≥3 antimicrobial classes) as reported by the National Antimicrobial Resistance Monitoring System. This review on <i>Salmonella</i> in swine addresses the current status of these topics by discussing antimicrobial resistance and metal tolerance in <i>Salmonella</i> and the contribution of horizontal gene transfer. A major challenge in controlling <i>Salmonella</i> is that <i>Salmonella</i> is a foodborne pathogen in humans but is often a commensal in food animals and thereby establishes an asymptomatic reservoir state in such animals, including swine. As food animal production systems continue to expand and antimicrobial usage becomes more limited, the need for <i>Salmonella</i> interventions has intensified. A promising mitigation strategy is vaccination against <i>Salmonella</i> in swine to limit animal, environmental, and food contamination.