title: An observational study of phagocytes and Klebsiella pneumoniae relationships: different behaviors.
abstract: Klebsiella pneumoniae is a bacterium that can be in relation with free living amoebae like Acanthamoeba castellanii in natural environments such as soil and water. This pathogen, which is responsible for community-acquired pneumonia and for nosocomial infections, also has interactions with host defense mechanisms like macrophages. As it has been shown that A. castellanii shares some traits with macrophages, in particular the ability to phagocyte bacteria, we have studied the uptake and the fate of the bacteria after contact with the two phagocytic cells. In our conditions, K. pneumoniae growth was increased in coculture in presence of A. castellanii or Thp-1 macrophagic cells and bacterial development was also increased by A. castellanii supernatant. In addition, we showed that the presence of the bacteria had a negative effect on the macrophages whereas it does not affect amoeba viability. Using gentamicin, which kills bacteria outside cells, we showed that only macrophages were able to internalize K. pneumoniae. This result was confirmed by electron microscopy. We have consequently reported some differences in bacterial uptake and internalization between a free living amoeba and macrophagic cells, highlighting the fact that results obtained with this amoebal model should not be extrapolated to the relationships between K. pneumoniae and macrophages.
authors.affiliation: Laboratoire Ecologie et Biologie des Interactions, Equipe Microbiologie de l'Eau, Université de Poitiers, UMR CNRS 7267, F-86073 Poitiers, France. Electronic address: elodie.maisonneuve@univ-poitiers.fr.
authors.forename: Elodie
authors.initials: E
authors.lastname: Maisonneuve
authors.affiliation: Laboratoire Ecologie et Biologie des Interactions, Equipe Microbiologie de l'Eau, Université de Poitiers, UMR CNRS 7267, F-86073 Poitiers, France; Laboratoire de parasitologie et mycologie médicale, Faculté de médecine et de pharmacie, 6, Rue de la Milétrie, 86034 Poitiers Cedex, France.
authors.forename: Estelle
authors.initials: E
authors.lastname: Cateau
authors.affiliation: Laboratoire de parasitologie et mycologie médicale, Faculté de médecine et de pharmacie, 6, Rue de la Milétrie, 86034 Poitiers Cedex, France.
authors.forename: Marion
authors.initials: M
authors.lastname: Delouche
authors.affiliation: Unité de pathologie ultrastructurale et expérimentale, Laboratoire d'anatomie et cytologie pathologiques, CHU la Milètrie, 2, Rue de la Milètrie, BP 577, 86021 Poitiers Cedex, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Quellard
authors.affiliation: Laboratoire Ecologie et Biologie des Interactions, Equipe Microbiologie de l'Eau, Université de Poitiers, UMR CNRS 7267, F-86073 Poitiers, France; Laboratoire de parasitologie et mycologie médicale, Faculté de médecine et de pharmacie, 6, Rue de la Milétrie, 86034 Poitiers Cedex, France.
authors.forename: Marie-Helene
authors.initials: MH
authors.lastname: Rodier
mesh_terms: D048248:Acanthamoeba castellanii / Q000378:metabolism* / Q000382:microbiology; D002460:Cell Line; D018920:Coculture Techniques; D005839:Gentamicins / Q000494:pharmacology; D054884:Host-Pathogen Interactions / Q000276:immunology / Q000502:physiology*; D006801:Humans; D007711:Klebsiella pneumoniae / Q000254:growth & development*; D008264:Macrophages / Q000276:immunology*; D010587:Phagocytosis / Q000502:physiology*
chemical_list: D005839:Gentamicins
keywords: Acanthamoeba castellanii; Interactions; Klebsiella pneumoniae; Macrophages