title: Inappropriate use of antibiotics in hospitals: the complex relationship between antibiotic use and antimicrobial resistance.
abstract: Hospitals are considered an excellent compartment for the selection of resistant and multi-drug resistant (MDR) bacteria. The overuse and misuse of antimicrobial agents are considered key points fuelling this situation. Antimicrobial stewardship programs have been designed for better use of these compounds to prevent the emergence of resistant microorganisms and to diminish the upward trend in resistance. Nevertheless, the relationship between antibiotic use and antimicrobial resistance is complex, and the desired objectives are difficult to reach. Various factors affecting this relationship have been advocated including, among others, antibiotic exposure and mutant selection windows, antimicrobial pharmacodynamics, the nature of the resistance (natural or acquired, including mutational and that associated with horizontal gene transfer) and the definition of resistance. Moreover, antimicrobial policies to promote better use of these drugs should be implemented not only in the hospital setting coupled with infection control programs, but also in the community, which should also include animal and environmental compartments. Within hospitals, the restriction of antimicrobials, cycling and mixing strategies and the use of combination therapies have been used to avoid resistance. Nevertheless, the results have not always been favorable and resistant bacteria have persisted despite the theoretical benefits of these strategies. Mathematical models as well as microbiological knowledge can explain this failure, which is mainly related to the current scenario involving MDR bacteria and overcoming the fitness associated with resistance. New antimicrobials, rapid diagnostic and antimicrobial susceptibility testing and biomarkers will be useful for future antimicrobial stewardship interventions.
authors.affiliation: Servicio de Microbiología, Hospital Universitario Ramón y Cajal and Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain; Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain; Unidad de Resistencia a Antibióticos y Virulencia Bacteriana, Consejo Superior de Investigaciones Científicas, Madrid, Spain. Electronic address: rafael.canton@salud.madrid.org.
authors.forename: Rafael
authors.initials: R
authors.lastname: Cantón
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Horcajada
authors.forename: Antonio
authors.initials: A
authors.lastname: Oliver
authors.forename: Patricia Ruiz
authors.initials: PR
authors.lastname: Garbajosa
authors.forename: Jordi
authors.initials: J
authors.lastname: Vila
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D024881:Drug Resistance, Bacterial; D006761:Hospitals; D006801:Humans; D057970:Inappropriate Prescribing
chemical_list: D000900:Anti-Bacterial Agents
keywords: Antibiotic use; Antimicrobial resistance; Bacterias multirresistentes; Compartimentos de selección; Multi-drug-resistant bacteria; Selección de resistencia; Selection compartments; Uso de antimicrobianos