title: In Vivo Evolution of Bacterial Resistance in Two Cases of Enterobacter aerogenes Infections during Treatment with Imipenem.
abstract: Infections caused by multidrug resistant (MDR) bacteria are a major concern worldwide. Changes in membrane permeability, including decreased influx and/or increased efflux of antibiotics, are known as key contributors of bacterial MDR. Therefore, it is of critical importance to understand molecular mechanisms that link membrane permeability to MDR in order to design new antimicrobial strategies. In this work, we describe genotype-phenotype correlations in Enterobacter aerogenes, a clinically problematic and antibiotic resistant bacterium. To do this, series of clinical isolates have been periodically collected from two patients during chemotherapy with imipenem. The isolates exhibited different levels of resistance towards multiple classes of antibiotics, consistently with the presence or the absence of porins and efflux pumps. Transport assays were used to characterize membrane permeability defects. Simultaneous genome-wide analysis allowed the identification of putative mutations responsible for MDR. The genome of the imipenem-susceptible isolate G7 was sequenced to closure and used as a reference for comparative genomics. This approach uncovered several loci that were specifically mutated in MDR isolates and whose products are known to control membrane permeability. These were omp35 and omp36, encoding the two major porins; rob, encoding a global AraC-type transcriptional activator; cpxA, phoQ and pmrB, encoding sensor kinases of the CpxRA, PhoPQ and PmrAB two-component regulatory systems, respectively. This report provides a comprehensive analysis of membrane alterations relative to mutational steps in the evolution of MDR of a recognized nosocomial pathogen.
authors.affiliation: UMR-MD1 -Transporteurs Membranaires, Chimiorésistance et Drug Design-Aix-Marseille Université et Institut de Recherche Biomédicale des Armées (IRBA), 27 Boulevard Jean Moulin, 13385 Marseille cedex 05, France.
authors.forename: Nadège
authors.initials: N
authors.lastname: Philippe
authors.affiliation: UMR-MD1 -Transporteurs Membranaires, Chimiorésistance et Drug Design-Aix-Marseille Université et Institut de Recherche Biomédicale des Armées (IRBA), 27 Boulevard Jean Moulin, 13385 Marseille cedex 05, France.
authors.forename: Laure
authors.initials: L
authors.lastname: Maigre
authors.affiliation: Laboratoire Information Génomique et Structurale-CNRS UMR7256 -Institut de Microbiologie de la Méditerranée (IMM, FR3479) Parc Scientifique de Luminy- 163 Avenue de Luminy-Case 934 FR-13288, Marseille cedex 09, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Santini
authors.affiliation: UMR-MD1 -Transporteurs Membranaires, Chimiorésistance et Drug Design-Aix-Marseille Université et Institut de Recherche Biomédicale des Armées (IRBA), 27 Boulevard Jean Moulin, 13385 Marseille cedex 05, France.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Pinet
authors.affiliation: Laboratoire Information Génomique et Structurale-CNRS UMR7256 -Institut de Microbiologie de la Méditerranée (IMM, FR3479) Parc Scientifique de Luminy- 163 Avenue de Luminy-Case 934 FR-13288, Marseille cedex 09, France.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Claverie
authors.affiliation: UMR-MD1 -Transporteurs Membranaires, Chimiorésistance et Drug Design-Aix-Marseille Université et Institut de Recherche Biomédicale des Armées (IRBA), 27 Boulevard Jean Moulin, 13385 Marseille cedex 05, France.
authors.forename: Anne-Véronique
authors.initials: AV
authors.lastname: Davin-Régli
authors.affiliation: UMR-MD1 -Transporteurs Membranaires, Chimiorésistance et Drug Design-Aix-Marseille Université et Institut de Recherche Biomédicale des Armées (IRBA), 27 Boulevard Jean Moulin, 13385 Marseille cedex 05, France.
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Pagès
authors.affiliation: UMR-MD1 -Transporteurs Membranaires, Chimiorésistance et Drug Design-Aix-Marseille Université et Institut de Recherche Biomédicale des Armées (IRBA), 27 Boulevard Jean Moulin, 13385 Marseille cedex 05, France.
authors.forename: Muriel
authors.initials: M
authors.lastname: Masi
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002463:Cell Membrane Permeability; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D021902:Enterobacter aerogenes / Q000187:drug effects / Q000235:genetics*; D004756:Enterobacteriaceae Infections / Q000188:drug therapy / Q000382:microbiology*; D019143:Evolution, Molecular; D016680:Genome, Bacterial; D006801:Humans; D015378:Imipenem / Q000494:pharmacology* / Q000627:therapeutic use; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA
chemical_list: D000900:Anti-Bacterial Agents; D015378:Imipenem