title: Assessment of Chromosomal DNA Fragmentation by Quinolones in an Isogenic Collection of Escherichia coli with Defined Resistance Mechanisms.
abstract: The aim of this study was to investigate the potential usefulness of DNA fragmentation as a quick and simple procedure for detecting resistance to fluoroquinolones (FQ) in isogenic Escherichia coli strains harboring defined and multiple quinolone resistance mechanisms, including low-level quinolone resistance (LLQR) phenotypes. DNA fragmentation assay (Micromax(®)) was evaluated for detecting resistance to FQ in 71 isogenic strains of E. coli harboring specific quinolone resistance mechanisms frequently found in clinical isolates. These isogenic strains represent a consistent and reliable model of increasing minimum inhibitory concentrations (MICs) of ciprofloxacin (CIP), ranging from 0.004 to 16 mg/L. According to CLSI criteria, the assay correctly identified all CIP-resistant strains (MIC ≥4 mg/L). As regards susceptible strains, 96% of bacterial strains were correctly assigned as susceptible to CIP. Moreover, the procedure enabled LLQR phenotypes to be efficiently identified; this subset may show different levels of DNA damage depending on the strain, even with similar MIC. Interestingly, despite increasing the dose according to the MIC, a lower response to quinolones occurs in strains with higher MIC values. This is a simple, rapid, and reliable test for evaluating susceptibility to FQ of E. coli, including the detection of strains harboring LLQR mechanisms.
authors.affiliation: 1 Department of Microbiology, University of Seville , Seville, Spain .|2 Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III , Madrid, Spain .
authors.forename: José-Manuel
authors.initials: JM
authors.lastname: Rodríguez-Martínez
authors.affiliation: 3 INIBIC-Complejo Hospitalario Universitario A Coruña , Unidad de Genética, A Coruña, Spain .|4 Laboratorio de Genética Molecular y Radiobiología, Centro Oncológico de Galicia , A Coruña, Spain .
authors.forename: Rebeca
authors.initials: R
authors.lastname: Santiso
authors.affiliation: 2 Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III , Madrid, Spain .|5 Infectious Diseases and Clinical Microbiology Unit, University Hospital Virgen Macarena , Seville, Spain .
authors.forename: Jesús
authors.initials: J
authors.lastname: Machuca
authors.affiliation: 2 Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III , Madrid, Spain .|6 INIBIC-Complejo Hospitalario Universitario A Coruña , Servicio de Microbiología, A Coruña, Spain .
authors.forename: Germán
authors.initials: G
authors.lastname: Bou
authors.affiliation: 1 Department of Microbiology, University of Seville , Seville, Spain .|2 Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III , Madrid, Spain .|5 Infectious Diseases and Clinical Microbiology Unit, University Hospital Virgen Macarena , Seville, Spain .
authors.forename: Álvaro
authors.initials: Á
authors.lastname: Pascual
authors.affiliation: 2 Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III , Madrid, Spain .|3 INIBIC-Complejo Hospitalario Universitario A Coruña , Unidad de Genética, A Coruña, Spain .|4 Laboratorio de Genética Molecular y Radiobiología, Centro Oncológico de Galicia , A Coruña, Spain .
authors.forename: José Luis
authors.initials: JL
authors.lastname: Fernández
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002876:Chromosomes, Bacterial / Q000737:chemistry / Q000187:drug effects*; D002939:Ciprofloxacin / Q000494:pharmacology*; D053938:DNA Fragmentation / Q000187:drug effects*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology; D005838:Genotype; D006801:Humans; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D012680:Sensitivity and Specificity
chemical_list: D000900:Anti-Bacterial Agents; D002939:Ciprofloxacin