Shiga toxins decrease enterohaemorrhagic Escherichia coli survival within Acanthamoeba castellanii

Authors

  • Samuel M. Chekabab,

    1. Centre de Recherche en Infectiologie Porcine (CRIP), Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada
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  • France Daigle,

    1. Centre de Recherche en Infectiologie Porcine (CRIP), Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada
    2. Department of Microbiology and Immunology, University of Montreal, Montréal, QC, Canada
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  • Steve J. Charette,

    1. Institut de Biologie Intégrative et des Systèmes, Pavillon Charles-Eugène-Marchand, Université Laval, Quebec City, QC, Canada
    2. Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie de Québec (Hôpital Laval), Quebec City, QC, Canada
    3. Département de Biochimie, de Microbiologie et de Bio-Informatique, Faculté des Sciences et de Génie, Université Laval, Quebec City, QC, Canada
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  • Charles M. Dozois,

    1. Centre de Recherche en Infectiologie Porcine (CRIP), Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada
    2. INRS-Institut Armand-Frappier, Laval, QC, Canada
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  • Josée Harel

    Corresponding author
    • Centre de Recherche en Infectiologie Porcine (CRIP), Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada
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Correspondence: Josée Harel, Centre de Recherche en Infectiologie Porcine (CRIP), Université de Montréal, Faculté de Médecine Vétérinaire, C.P. 5000, Saint-Hyacinthe, QC, Canada J2S 7C6. Tel.: +1 450 773 8521; fax: +1 450 778 8108;

e-mail: josee.harel@umontreal.ca

Abstract

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.

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