Centre de Recherche en Infectiologie Porcine (CRIP), Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada.
FEMS Microbiol Lett. 2013 Jul;344(1):86-93. doi: 10.1111/1574-6968.12158. Epub 2013 Apr 29.
Enterohaemorrhagic Escherichia coli (EHEC) are zoonotic pathogens transmitted to humans through contaminated water or bovine products. One of the strategies used by pathogenic bacteria to survive in aquatic environments is using free-living amoebae as hosts. Acanthamoeba castellanii is an amoeba known to host several waterborne pathogens. This study investigates the survival of EHEC with A. castellanii, which could contribute to its spread and transmission to humans. We used a gentamicin protection assay as well as fluorescence and electron microscopy to monitor the intra-amoebae survival of EHEC O157:H7 over 24 h. The results showed that EHEC were able to survive within A. castellanii and that this survival was reduced by Shiga toxins (Stx) produced by EHEC. A toxic effect mediated by Stx was demonstrated by amoebae mortality and LDH release during co-culture of EHEC and amoeba. This work describes the ability of EHEC to survive within A. castellanii, and this host-pathogen interaction is partially controlled by the Stx. Thus, this ubiquitous amoeba could represent an environmental niche for EHEC survival and transmission.
产志贺毒素（Shiga toxins，Stx）的肠出血性大肠杆菌（Enterohaemorrhagic Escherichia coli，EHEC）是通过污染的水或牛产品传播给人类的人畜共患病病原体。致病性细菌在水生环境中生存的策略之一是利用自由生活的变形虫作为宿主。已知棘阿米巴（Acanthamoeba castellanii）是几种水源性病原体的宿主。本研究调查了 EHEC 与棘阿米巴的共生情况，这可能有助于其传播和传播给人类。我们使用庆大霉素保护试验以及荧光和电子显微镜来监测 24 小时内 EHEC O157:H7 在变形虫内的存活情况。结果表明，EHEC 能够在棘阿米巴内存活，并且这种存活被 EHEC 产生的志贺毒素（Stx）所减少。通过 EHEC 和变形虫共培养过程中的变形虫死亡率和 LDH 释放，证明了 Stx 介导的毒性作用。本工作描述了 EHEC 在棘阿米巴内生存的能力，这种宿主-病原体相互作用部分受到 Stx 的控制。因此，这种无处不在的变形虫可能代表了 EHEC 生存和传播的环境小生境。
