Laboratory of Animal Microbiology, Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, 468-1, Aramaki Aza Aoba, Aoba-ku, Sendai 980-0845, Japan.
Animal Research Center, Sapporo Medical University, Minami 1, Nishi 16, Sapporo 060-8556, Japan.
Pathog Dis. 2019 Jun 1;77(4). doi: 10.1093/femspd/ftz036.
Susceptibility to enterohemorrhagic Escherichia coli (EHEC) infection varies among humans. The intestinal microbiota seems to play an essential role in host defense against EHEC; thus, we hypothesized that indigenous bacteria, such as Clostridium ramosum and Clostridium perfringens, could influence the susceptibility to EHEC infection. To evaluate the effect of indigenous bacteria on EHEC infection, germ-free mice were precolonized with each indigenous bacterium, and then infected with EHEC O157:H7. Precolonization with C. ramosum or C. perfringens completely prevented death from EHEC infection througout a test period. Precolonization with C. ramosum also reduced the level of secreted Shiga toxin (Stx) 2 and prevented histopathological changes in the kidneys in a similar way to precolonization with Bifidobacterium longum, which is used as a model for preventing EHEC infection. In contrast, the mice precolonized with C. perfringens showed mild renal injuries. When evaluated using an in vitro co-culturing system, again C. ramosum inhibited the growth and Stx production of EHEC more potently than C. perfringens. These results indicate that C. ramosum and C. perfringens suppressed EHEC infection; however, the extent of their preventive effects differed. Therefore, the susceptibility to EHEC infection and its severity can depend on the functional bacteria present in the intestinal microbiota of individuals.
人类对肠出血性大肠杆菌（EHEC）感染的易感性存在差异。肠道微生物群似乎在宿主防御 EHEC 方面发挥着重要作用；因此，我们假设土著细菌，如 C. ramosum 和 C. perfringens，可以影响 EHEC 感染的易感性。为了评估土著细菌对 EHEC 感染的影响，无菌小鼠用每种土著细菌预先定植，然后用 EHEC O157:H7 感染。用 C. ramosum 或 C. perfringens 预先定植可完全预防 EHEC 感染导致的死亡，整个试验期间都是如此。用 C. ramosum 预先定植还以类似于用长双歧杆菌（用作预防 EHEC 感染的模型）预先定植的方式降低了分泌型 Shiga 毒素（Stx）2 的水平，并防止了肾脏的组织病理学变化。相比之下，用 C. perfringens 预先定植的小鼠显示出轻微的肾脏损伤。当使用体外共培养系统进行评估时，C. ramosum 再次比 C. perfringens 更有效地抑制了 EHEC 的生长和 Stx 产生。这些结果表明 C. ramosum 和 C. perfringens 抑制了 EHEC 感染；然而，它们的预防效果程度不同。因此，EHEC 感染的易感性及其严重程度可能取决于个体肠道微生物群中存在的功能性细菌。
