title: Plasmid-mediated quinolone resistance: Two decades on.
abstract: After two decades of the discovery of plasmid-mediated quinolone resistance (PMQR), three different mechanisms have been associated to this phenomenon: target protection (Qnr proteins, including several families with multiple alleles), active efflux pumps (mainly QepA and OqxAB pumps) and drug modification [AAC(6')-Ib-cr acetyltransferase]. PMQR genes are usually associated with mobile or transposable elements on plasmids, and, in the case of qnr genes, are often incorporated into sul1-type integrons. PMQR has been found in clinical and environmental isolates around the world and appears to be spreading. Although the three PMQR mechanisms alone cause only low-level resistance to quinolones, they can complement other mechanisms of chromosomal resistance to reach clinical resistance level and facilitate the selection of higher-level resistance, raising a threat to the treatment of infections by microorganisms that host these mechanisms.
authors.affiliation: Departamento de Microbiología, Universidad de Sevilla, Sevilla, Spain; 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: Departamento de Microbiología, Universidad de Sevilla, Sevilla, Spain; Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III, Madrid, Spain; Unidad de Enfermedades Infecciosas y Microbiología Clínica, Hospital Universitario Virgen Macarena, Sevilla, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Machuca
authors.affiliation: Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III, Madrid, Spain; Hospital Universitario Marqués de Valdecilla-IDIVAL, Santander, Spain.
authors.forename: María Eliecer
authors.initials: ME
authors.lastname: Cano
authors.affiliation: Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III, Madrid, Spain; Hospital Universitario Marqués de Valdecilla-IDIVAL, Santander, Spain.
authors.forename: Jorge
authors.initials: J
authors.lastname: Calvo
authors.affiliation: Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III, Madrid, Spain; Hospital Universitario Marqués de Valdecilla-IDIVAL, Santander, Spain; Departamento de Biología Molecular, Universidad de Cantabria, Santander, Spain. Electronic address: lmartinez@humv.es.
authors.forename: Luis
authors.initials: L
authors.lastname: Martínez-Martínez
authors.affiliation: Departamento de Microbiología, Universidad de Sevilla, Sevilla, Spain; Spanish Network for the Research in Infectious Diseases (REIPI RD12/0015), Instituto de Salud Carlos III, Madrid, Spain; Unidad de Enfermedades Infecciosas y Microbiología Clínica, Hospital Universitario Virgen Macarena, Sevilla, Spain.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Pascual
mesh_terms: D000123:Acetyltransferases / Q000235:genetics / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001424:Bacterial Infections / Q000188:drug therapy / Q000382:microbiology; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002876:Chromosomes, Bacterial / Q000737:chemistry / Q000378:metabolism; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D006094:Gram-Positive Bacteria / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D015363:Quinolones / Q000494:pharmacology; D017211:Treatment Failure
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D020033:Protein Isoforms; C524438:QepA protein, E coli; C485385:Qnr protein, Klebsiella pneumoniae; D015363:Quinolones; D000123:Acetyltransferases; C056532:aminoglycoside N(6')-acetyltransferase
keywords: AAC(6′)-Ib-cr; OqxAB; Plasmid; QepA; Qnr; Quinolone; Resistance