Files
Abstract
Salmonella enterica is among the most common causes of healthcare-associated infections in horses. Outbreaks in veterinary hospitals and other equine facilities are often costly in terms of morbidity, mortality, and financial impact. While the detection and prevention of Salmonella infections in horses have long been recognized as a priority of equine infection control programs, these efforts continue to be a challenge, in part due to remaining gaps in our understanding of the epidemiology of this pathogen in horses, as well as limitations of available diagnostic tests. To address the lack of objective information about the sensitivity and specificity of the most commonly used tests to detect Salmonella in equine fecal samples – culture and polymerase chain reaction (PCR) – we first performed a systematic review of the literature to evaluate the performance of these tests, which revealed wide variability in reported test methods. In the second study, we compared the performance of a novel rapid test for Salmonella in horses against culture and PCR, demonstrating the utility of the rapid test as a point-of-care screening test for use in equine facilities, and providing objective information about the sensitivity and specificity of existing tests. Next, we addressed two key pieces of the epidemiology of Salmonella in horses that have been poorly described to date – the duration of fecal shedding among infected horses, and the relationship of Salmonella shedding and the equine gastrointestinal microbiome. By following Salmonella-positive horses over time, we demonstrated that they shed the bacteria in their feces for a median of thirteen days but are likely to shed longer if they have experienced clinical illness. Additionally, we provided preliminary evidence that among horses with subclinical Salmonella infections, gastrointestinal microbiome composition may be associated with Salmonella shedding patterns over time. Altogether, this work fills key knowledge gaps that have historically hindered the effective management of Salmonella-positive horses in hospital settings and the provision of evidence-based clinical guidance to the owners of these horses. The tools and evidence provided herein bring us closer to reducing the negative impact of Salmonella infections on equine populations.