title: Decreased permeability and enhanced proton-dependent active efflux in the development of resistance to quinolones in Morganella morganii.
abstract: Five quinolone-resistant strains were developed from a clinical Morganella morganii isolate (M1 strain) which was susceptible to nalidixic acid and fluoroquinolones. All five in vitro selected mutants showed diminished norfloxacin accumulation and two of them also decreased the expression of the AgO in the outer membrane lipopolysaccharide with respect to their parent strain and to the M. morganii NCTC-235 type strain. Likewise, the M1 strain did not express a 37-38 kDa protein and accumulated less norfloxacin than the M. morganii NCTC-235 strain. The decreased norfloxacin uptake in the five mutants compared with the M. morganii NCTC-235 strain was due to an enhanced proton-dependent active efflux plus a pre-existent decreased expression of a 37-38 kDa protein in the parent strain.
authors.affiliation: Microbiology, Department of Clinical Sciences, School of Medicine, University of Las Palmas de G.C., Dr Pasteur s/n, 35080, Las Palmas, Spain. mmtavio@retemail.es
authors.forename: M M
authors.initials: MM
authors.lastname: Tavío
authors.forename: J
authors.initials: J
authors.lastname: Vila
authors.forename: J
authors.initials: J
authors.lastname: Ruiz
authors.forename: A M
authors.initials: AM
authors.lastname: Martín Sánchez
authors.forename: M T
authors.initials: MT
authors.lastname: Jiménez de Anta
mesh_terms: D042462:4-Quinolones; D000890:Anti-Infective Agents / Q000493:pharmacokinetics / Q000494:pharmacology*; D001693:Biological Transport, Active; D002463:Cell Membrane Permeability; D004352:Drug Resistance, Microbial / Q000235:genetics; D008826:Microbial Sensitivity Tests; D020613:Morganella morganii / Q000187:drug effects* / Q000235:genetics; D009154:Mutation; D011522:Protons
chemical_list: D042462:4-Quinolones; D000890:Anti-Infective Agents; D011522:Protons