Martin-Gutierrez, GuillermoRodriguez-Martinez, Jose ManuelPascual, AlvaroRodriguez-Beltran, JeronimoBlazquez, Jesus2023-02-122023-02-122017-04Martín-Gutiérrez G, Rodríguez-Martínez JM, Pascual Á, Rodríguez-Beltrán J, Blázquez J. Plasmidic qnr Genes Confer Clinical Resistance to Ciprofloxacin under Urinary Tract Physiological Conditions. Antimicrob Agents Chemother. 2017 Mar 24;61(4):e02615-160066-4804http://hdl.handle.net/10668/19015Escherichia coli variants expressing plasmid- mediated qnr genes are usually susceptible to fluoroquinolones by standard susceptibility testing. Here we show that, under specific urinary tract physiological conditions, susceptible laboratory and clinical strains harboring qnr determinants become fully resistant to ciprofloxacin (CIP). Therefore, physiological conditions, mainly urine pH values, should be considered when performing susceptibility testing of CIP activity against E. coli in treating urinary tract infection (UTI) and for selecting appropriate antibiotics for UTI treatment.enciprofloxacinEscherichia coliMICpHqnrurinary tract infectionMediated quinolone resistanceFluoroquinolone resistanceEscherichia-coliKlebsiella-pneumoniaeAac(6')-ib-crEpidemiologyInfectionsMutationsCiprofloxacinAnti-Bacterial AgentsFluoroquinolonesEscherichia coliUrinary Tract InfectionsPlasmidsHydrogen-Ion Concentrationresearch articleRestricted AccessInfecciones urinariasCiprofloxacinaFluoroquinolonasAntibacterianosPlásmidosLaboratorios10.1128/AAC.02615-161098-6596https://europepmc.org/articles/pmc5365700?pdf=render397598800079