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Les ilôts de résistance de type SGI1 (Salmonella Genomic Island 1) et apparentés dans des souches humaines cliniques de Porteus mirabilis et Salmonella enterica

Abstract : Salmonella genomic island (SGI1) is an integrative mobilizable element initially described in an epidemic multidrug-resistant Salmonella Typhimurium DT104. Since this first report, many variants and related genomic islands (Proteus genomic island 1 (PGI1)) have been described among Salmonella enterica serovars and in Proteus mirabilis. These islands have a stable backbone and a highly variable multidrug-resistant (MDR) region. The objective of this work was to study SGI1 from clinical P. mirabilis isolates (University hospitals of Dijon and Lariboisière - Paris) and S. enterica (University hospital of Dijon) The prevalence of these islands ranged from 5% to 16% in P. mirabilis with at least one acquired resistance. The genotypic analysis revealed a wide diversity among isolates but also the presence of some clonal isolates harbouring SGI1 or PGI1. Genomic island sequencing revealed the great plasticity of MDR regions, primarily mediated by IS26. Thanks to IS26 movements, the MDR region gains resistance genes (such as blaCTX-M-15) present in structures initially detected in plasmids from widely distributed Enterobacteriaceae. Many species of Enterobacteriaceae that harbour IncA/C plasmids are able to acquire islands by conjugation. These islands are then incorporated into specific sites on the chromosome (trmE). They could also be completely excised from Enterobacteriaceae under antibiotic pressure in the presence of an IncA/C plasmid. Genomic islands should be regarded on the one hand as a steady interface of resistance and on the other hand as a dynamic interface conveying resistance genes. Finally, SGI1 of S. enterica was not found to increase virulence in a Caenorhabditis elegans model or in a retrospective clinical study (12% of prevalence). However, it seems that P. mirabilis becomes more virulent when it harbours SGI1 in Caenorhabditis elegans
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Claire Goulard de Curraize. Les ilôts de résistance de type SGI1 (Salmonella Genomic Island 1) et apparentés dans des souches humaines cliniques de Porteus mirabilis et Salmonella enterica. Bactériologie. Université Bourgogne Franche-Comté, 2017. Français. ⟨NNT : 2017UBFCE013⟩. ⟨tel-02495619⟩

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