Inhibition of enterohemorrhagic O157:H7 infection in a gnotobiotic mouse model with pre-colonization by strains.

Enterohemorrhagic (EHEC) O157:H7 has been known to cause outbreaks of hemorrhagic colitis and hemolytic uremic syndrome. We previously demonstrated that intestinal flora contribute to the prevention of EHEC infection in a mouse model. However, it has not yet been determined whether , a predominant genus in the human intestine, contributes to the prevention of EHEC infection. The aim of the present study was to investigate the effect of () and (B. vulgatus) on EHEC O157:H7 infection using gnotobiotic mice. These strains were inoculated into germ-free mice to create a gnotobiotic mouse model. EHEC was inoculated into the mice, which were then monitored for 7 days for any change in symptoms. The mice that had been pre-colonized with the strains did not develop lethal EHEC infection, although several inflammatory symptoms were observed in the pre-colonized group. However, no inflammatory symptoms were identified in the pre-colonized group. Moreover, exerted an inhibitory effect on enterocyte-like cell apoptosis. protected HT29 cells from apoptosis caused by Shiga toxin. In conclusion, the findings of the present study demonstrated that colonization by strains can inhibit EHEC infection.