Escherichia coli, de la colonisation oropharyngée à l'infection pulmonaire : épidémiologie et physiopathologie

Abstract : Ventilator associated pneumonia (VAP) is the main infectious complication in intensive care unit (ICU) patients. Its pathophysiology relies on oropharyngeal colonisation, and so does its prevention. Escherichia coli is one of its main responsible pathogen. Nevertheless, data on E. coli implication in this context is cruelly missing.We tend to a multi-facets approach of E. coli VAP. This thesis’ objectives are: to update current VAP epidemiology, with regard to enterobacteriaceae in general, and E. coli in particular; to describe phenotypic and genotypic characteristics of E. coli isolates responsible for respiratory colonization or infection; to study pathogenic Gram-negative bacilli oropharyngeal colonization in populations of various severity; and to describe phenotypic and genotypic characteristics of oropharyngeal E. coli isolates and compare them to their rectal counterpart.In our first work, we confirm the importance of enterobacteriaceae as first-line VAP pathogens. Among those, E. coli is of particular matter, with regard to antimicrobial resistance. Predominance of B2 phylogroup among E. coli respiratory isolates has been confirmed in a single-ICU study, and a wide national survey of ICU patients. Furthermore, B2 phylogroup has been shown to prevail in oropharyngeal and rectal E. coli isolates. Next, we confirmed extra-intestinal virulence with a correlation between virulence factor content and mortality in a mouse pneumonia model. Last, a large-scale epidemiological study of oropharyngeal colonization in general, and of E. coli characteristics which composes it, in patients of different severity and in healthy subjects is ongoing. This data will allow a deeper insight of VAP pathophysiology, a better knowledge of E. coli population of oropharyngeal colonization and causing VAP. Targeted preventive measures could therefore be evaluated.
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Jonathan Messika. Escherichia coli, de la colonisation oropharyngée à l'infection pulmonaire : épidémiologie et physiopathologie. Microbiologie et Parasitologie. Université Sorbonne Paris Cité, 2017. Français. ⟨NNT : 2017USPCC285⟩. ⟨tel-02186131⟩

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