title: [Tolerance and heteroresistance in Gram-positive microorganisms].
abstract: During the last few years, insufficient efficacy of currently recommended antimicrobial agents has been observed, mainly in the case of glycopeptides, during the treatment of infections due to methicillin-resistant Staphylococcus aureus, even if these isolates show MIC values within the susceptible range. The phenomena associated with this observation are tolerance (a genetic event in which a bactericidal antibiotic fails to kill a bacterial population), persistence (a non-inherited and transient phenotypic phenomenon in which a bacterial subpopulation -0.1%-10%- survive lethal antimicrobial concentrations irrespective of the mechanisms of action) and heteroresistance (an epigenetic event in which less susceptible isogenic subpopulations are recovered when the entire population is challenged with concentrations exceeding MIC values). New antimicrobials, including daptomycin, are less affected by these phenomena and should be considered as the treatment of choice when these events are demonstrated or suspected.
authors.affiliation: Servicio de Microbiología y CIBER de Investigación en Salud Pública, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Hospital Universitario Ramón y Cajal, Madrid, España.
authors.forename: María Isabel
authors.initials: MI
authors.lastname: Morosini
authors.forename: Rafael
authors.initials: R
authors.lastname: Cantón
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D018441:Biofilms / Q000187:drug effects; D017576:Daptomycin / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D013293:Enterococcus faecalis / Q000187:drug effects; D044127:Epigenesis, Genetic; D006020:Glycopeptides / Q000494:pharmacology / Q000627:therapeutic use; D006094:Gram-Positive Bacteria / Q000187:drug effects* / Q000235:genetics; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D006020:Glycopeptides; D017576:Daptomycin