Sensitivity of dairy calfSalmonella entericaserotype Cerro isolates to infection-relevant stressors

Abstract

AbstractSalmonella entericaserotype Cerro (S.Cerro) is an emergingSalmonellaserotype isolated from cattle, but the association ofS.Cerro with disease is not well understood. While comparative genomic analyses of bovineS.Cerro isolates have indicated mutations in elements associated with virulence, the correlation ofS.Cerro fecal shedding with clinical disease in cattle varies between epidemiologic studies. The primary objective of this study was to characterize the infection-relevant phenotypes ofS.Cerro fecal isolates obtained from neonatal calves born on a dairy farm in Wisconsin, USA. TheS.Cerro isolates varied in biofilm production and sensitivity to the bile salt deoxycholate. AllS.Cerro isolates were sensitive to sodium hypochlorite, hydrogen peroxide, and acidic shock. However,S.Cerro isolates were resistant to nitric oxide stress. TwoS. Cerro isolates were unable to compete withS.Typhimurium during infection of calf ligated intestinal loops, indicating decreased fitnessin vivo. Together, our data suggest thatS.Cerro is sensitive to some innate antimicrobial defenses present in the gut, many of which are also used to controlSalmonellain the environment. The observed phenotypic variation inS.Cerro isolates from a single farm suggest phenotypic plasticity that could impact infectious potential, transmission, and persistence on a farm.ImportanceSalmonella entericais a zoonotic pathogen that threatens both human and animal health.Salmonella entericaserotype Cerro is being isolated from cattle at increasing frequency over the past two decades, however its association with clinical disease is unclear. The goal of this study was to characterize infection-relevant phenotypes ofS.Cerro isolates obtained from dairy calves from a single farm. Our work shows that there can be variation among temporally-relatedS.Cerro isolates and that these isolates are sensitive to killing by toxic compounds of the innate immune system and those used for environmental control ofSalmonella. This work contributes to our understanding of the pathogenic potential of the emerging pathogenS. Cerro.