Abstract
Upon colonization of the intestinal epithelium, the attaching and effacing (AE) pathogen Enterohemorrhagic Escherichia coli (EHEC) effaces microvilli and forms pedestal-like structures beneath the adherent bacterium. The production of one of its virulence factors, the phage-encoded Shiga toxin (Stx) results in systemic disease, including the development of renal failure. Although EHEC does not productively infect conventional mice, EHEC infection can be modeled in mice utilizing a derivative of the natural murine AE pathogen Citrobacter rodentium (CR). Gavage of mice with CR(ΦStx2dact), a C. rodentium lysogenized by a phage encoding an Stx variant with high potency in mice, features AE lesion formation on intestinal epithelium and Stx-mediated systemic disease, including renal damage. This model is somewhat limited by mouse-to-mouse variation in the course of disease, with the time to severe morbidity (and required euthanasia) varying by as many as 5 days, a feature that limits pathological analysis at defined stages of disease. In the current study, we altered and optimized the preparation, dose, and mode of delivery of CR(ΦStx2dact), using food-borne route of infection to generate highly synchronous disease model. We found that food-borne inoculation of as few as 3 × 104 CR(ΦStx2dact) resulted in productive colonization and severe systemic disease. Upon inoculation of 1 × 108 bacteria, the majority of infected animals suffered weight loss beginning 5 days post-infection and all required euthanasia on day 6 or 7. This enhanced murine model for EHEC infection should facilitate characterization of the pathology associated with specific phases of Stx-mediated disease.
Highlights
Enterohemorrhagic E. coli (EHEC) is a member of the family of pathogenic bacteria known as attaching and effacing pathogens (AE pathogens), which include enteropathogenic E. coli (EPEC) and Citrobacter rodentium (CR)
Host-adapted C. rodentium present in the feces of infected mice are in a hyper-infectious state, i.e., highly transmissible and capable of accelerated colonic colonization, compared to C. rodentium grown in LB (Wiles et al, 2005)
Serious life-threatening cases of EHEC infection evolve through successive phases of illness, beginning asymptomatically but followed by the development of non-bloody diarrhea, bloody diarrhea, and, in the most serious cases, culminating in hemolytic uremic syndrome (HUS)
Summary
Enterohemorrhagic E. coli (EHEC) O157:H7 is a Gram-negative bacterium and a causative agent of intestinal and systemic disease (Wadolkowski et al, 1990a; Robinson et al, 2006; Mohawk and O’Brien, 2011; Melton-Celsa et al, 2012; Kaper and O’Brien, 2014). EHEC is a member of the family of pathogenic bacteria known as attaching and effacing pathogens (AE pathogens), which include enteropathogenic E. coli (EPEC) and Citrobacter rodentium (CR). These organisms are capable of Synchronous Model for EHEC Infection triggering localized actin assembly on epithelial cells beneath bound bacteria, forming pedestal-like structures (Brady et al, 2007; Vingadassalom et al, 2009; Lai et al, 2013). EHEC infection exhibits distinct clinical phases such as non-bloody diarrhea, followed by bloody diarrhea, and systemic disease, the latter manifested most commonly by hemolytic uremic syndrome (HUS), the triad of hemolytic anemia, thromobocytopenia and renal failure (Keepers et al, 2006; Obrig, 2010; Melton-Celsa et al, 2012; Davis et al, 2014; Melton-Celsa and O’Brien, 2014; Freedman et al, 2016)
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