title: Modulation of Membrane Influx and Efflux in Escherichia coli Sequence Type 131 Has an Impact on Bacterial Motility, Biofilm Formation, and Virulence in a Caenorhabditis elegans Model.
abstract: Energy-dependent efflux overexpression and altered outer membrane permeability (influx) can promote multidrug resistance (MDR). The present study clarifies the regulatory pathways that control membrane permeability in the pandemic clone Escherichia coli sequence type 131 (ST131) and evaluates the impact of efflux and influx modulations on biofilm formation, motility, and virulence in the Caenorhabditis elegans model. Mutants of two uropathogenic E. coli (UPEC) strains, MECB5 (ST131; H30-Rx) and CFT073 (ST73), as well as a fecal strain, S250 (ST131; H22), were in vitro selected using continuous subculture in subinhibitory concentrations of ertapenem (ETP), chloramphenicol (CMP), and cefoxitin (FOX). Mutations in genes known to control permeability were shown for the two UPEC strains: MECB5-FOX (deletion of 127 bp in marR; deletion of 1 bp and insertion of an IS1 element in acrR) and CFT073-CMP (a 1-bp deletion causing a premature stop in marR). We also demonstrated that efflux phenotypes in the mutants selected with CMP and FOX were related to the AcrAB-TolC pump, but also to other efflux systems. Alteration of membrane permeability, caused by underexpression of the two major porins, OmpF and OmpC, was shown in MECB5-ETP and mutants selected with FOX. Lastly, our findings suggest that efflux pump-overproducing isolates (CMP mutants) pose a serious threat in terms of virulence (significant reduction in worm median survival) and host colonization. Lack of porins (ETP and FOX mutants) led to a high level of antibiotic resistance in an H30-Rx subclone. Nevertheless, this adaptation created a physiological disadvantage (decreased motility and ability to form biofilm) associated with a low potential for virulence.
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U1047, Université de Montpellier, UFR de Médecine, Nîmes, France Service de Microbiologie, CHU Carémeau, Nîmes University Hospital, Nîmes, France.
authors.forename: Alix
authors.initials: A
authors.lastname: Pantel
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U1047, Université de Montpellier, UFR de Médecine, Nîmes, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Dunyach-Remy
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U1047, Université de Montpellier, UFR de Médecine, Nîmes, France.
authors.forename: Christelle
authors.initials: C
authors.lastname: Ngba Essebe
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U1047, Université de Montpellier, UFR de Médecine, Nîmes, France.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Mesureur
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U1047, Université de Montpellier, UFR de Médecine, Nîmes, France Service de Maladies Infectieuses et Tropicales, CHU Carémeau, Nîmes University Hospital, Nîmes, France.
authors.forename: Albert
authors.initials: A
authors.lastname: Sotto
authors.affiliation: Transporteurs Membranaires, Chimiorésistance et Drug Design, Facultés de Médecine et Pharmacie, UMR-MD1, IRBA-Université Aix-Marseille, Marseille, France.
authors.forename: Jean-Marie
authors.identifier: 0000-0001-7092-7977
authors.initials: JM
authors.lastname: Pagès
authors.affiliation: Service de Microbiologie, Hôpital Beaujon, AP-HP, Clichy, France Faculté de Médecine, Université Paris Diderot, Paris, France INSERM, UMR 1149, Université Paris Diderot, Paris, France.
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Nicolas-Chanoine
authors.affiliation: Institut National de la Santé et de la Recherche Médicale, U1047, Université de Montpellier, UFR de Médecine, Nîmes, France Service de Microbiologie, CHU Carémeau, Nîmes University Hospital, Nîmes, France jean.philippe.lavigne@chu-nimes.fr.
authors.forename: Jean-Philippe
authors.identifier: 0000-0002-9484-0304
authors.initials: JP
authors.lastname: Lavigne
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects; D001692:Biological Transport / Q000502:physiology; D017173:Caenorhabditis elegans / Q000382:microbiology; D002440:Cefoxitin / Q000494:pharmacology; D002701:Chloramphenicol / Q000494:pharmacology; D000077727:Ertapenem; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D014774:Virulence; D047090:beta-Lactams / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D002701:Chloramphenicol; D002440:Cefoxitin; D000077727:Ertapenem