title: Co-resistance: an opportunity for the bacteria and resistance genes.
abstract: Co-resistance involves transfer of several genes into the same bacteria and/or the acquisition of mutations in different genetic loci affecting different antimicrobials whereas pleiotropic resistance implies the same genetic event affecting several antimicrobials. There is an increasing prevalence of isolates with co-resistance which are over-represented within the so-called high-risk clones. Compensatory events avoid fitness cost of co-resistance, even in the absence of antimicrobials. Nevertheless, they might be selected by different antimicrobials and a single agent might select co-resistant isolates. This process, named as co-selection, is not avoided with cycling or mixing strategies of antimicrobial use. Co-resistance and co-selection processes increase the opportunity for persistence of the bacteria and resistance genes and should be considered when designing strategies for decreasing antimicrobial resistance.
authors.affiliation: Servicio de Microbiología and CIBER en Epidemiología y Salud Pública, Hospital Universitario Ramón y Cajal and Instituto Ramón y Cajal de Investigación Sanitaria, Carretera Colmenar Km 9.1. 28034 Madrid, Spain. rcanton.hrc@salud.madrid.org
authors.forename: Rafael
authors.initials: R
authors.lastname: Cantón
authors.forename: Patricia
authors.initials: P
authors.lastname: Ruiz-Garbajosa
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D001419:Bacteria / Q000187:drug effects / Q000235:genetics; D001424:Bacterial Infections / Q000188:drug therapy / Q000235:genetics*; D002999:Clone Cells; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004363:Drug Utilization; D005798:Genes, Bacterial / Q000187:drug effects; D019450:Genes, MDR / Q000235:genetics; D056084:Genetic Fitness; D006801:Humans; D009154:Mutation; D012641:Selection, Genetic / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents