Sensitivity of dairy calf <i>Salmonella enterica</i> serotype Cerro isolates to infection-relevant stressors

<i>Salmonella enterica</i> serotype Cerro (<i>S</i>. Cerro) is an emerging <i>Salmonella</i> serotype isolated from cattle, but the association of <i>S</i>. Cerro with disease is not well understood. While comparative genomic analyses of bovine <i>S</i>. Cerro isolates have indicated mutations in elements associated with virulence, the correlation of <i>S</i>. 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 of <i>S</i>. Cerro fecal isolates obtained from neonatal calves born on a dairy farm in Wisconsin, USA. The <i>S</i>. Cerro isolates varied in biofilm production and sensitivity to the bile salt deoxycholate. All <i>S</i>. Cerro isolates were sensitive to sodium hypochlorite, hydrogen peroxide, and acidic shock. However, <i>S</i>. Cerro isolates were resistant to nitric oxide stress. Two <i>S</i>. Cerro isolates were unable to compete with <i>S</i>. Typhimurium during infection of calf ligated intestinal loops, indicating decreased fitness <i>in vivo</i>. Together, our data suggest that <i>S</i>. Cerro is sensitive to some innate antimicrobial defenses present in the gut, many of which are also used to control <i>Salmonella</i> in the environment. The observed phenotypic variation in <i>S</i>. Cerro isolates from a single farm suggest phenotypic plasticity that could impact infectious potential, transmission, and persistence on a farm.IMPORTANCE<i>Salmonella enterica</i> is a zoonotic pathogen that threatens both human and animal health. <i>Salmonella enterica</i> serotype 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 of <i>S</i>. Cerro isolates obtained from dairy calves from a single farm. Our work shows that there can be variation among temporally related <i>S</i>. Cerro isolates and that these isolates are sensitive to killing by toxic compounds of the innate immune system and those used for environmental control of <i>Salmonella</i>. This work contributes to our understanding of the pathogenic potential of the emerging pathogen <i>S</i>. Cerro.