title: Micafungin is more active against Candida albicans biofilms with high metabolic activity.
abstract: BACKGROUND
  The ability to form biofilm enables Candida spp. to cause catheter-related candidaemia. The use of agents with in vitro activity against Candida albicans biofilms, such as micafungin, could obviate catheter removal. The metabolic activity of C. albicans biofilms is strain-dependent, and cell wall formation is thought to be more prominent in biofilms showing high metabolic activity.
  
  
  METHODS
  We studied the antifungal activity of micafungin against 265 C. albicans isolates with different degrees of metabolic activity causing fungaemia in 246 patients admitted to Gregorio Marañón Hospital (January 2007 to June 2013). All strains were classified according to the metabolic activity of their biofilm, which was classified as low, moderate and high using XTT. Micafungin MICs for planktonic and sessile cells were assessed using the EUCAST E.Def 7.2 procedure and XTT reduction assay, respectively. The MIC was defined as a 50% and 80% reduction in metabolic activity compared with the control well.
  
  
  RESULTS
  Micafungin was uniformly more active against planktonic cells than against sessile cells (MIC50 ≤ 0.015 versus 8 mg/L), although it was not consistently active against all C. albicans biofilms. Isolates with low metabolic activity biofilms showed the lowest susceptibility to micafungin, followed by moderate and high metabolic activity biofilms (P < 0.001).
  
  
  CONCLUSIONS
  Our study suggests that the metabolic activity of biofilm may have a role in future evaluations of micafungin for the eradication of C. albicans biofilms (e.g. the lock therapy approach).
authors.affiliation: Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio Marañón, Madrid, Spain Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain.
authors.forename: Laura Judith
authors.initials: LJ
authors.lastname: Marcos-Zambrano
authors.affiliation: Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio Marañón, Madrid, Spain Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain CIBER Enfermedades Respiratorias-CIBERES (CB06/06/0058), Madrid, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Escribano
authors.affiliation: Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio Marañón, Madrid, Spain Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain.
authors.forename: Marcela
authors.initials: M
authors.lastname: González del Vecchio
authors.affiliation: Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio Marañón, Madrid, Spain Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain CIBER Enfermedades Respiratorias-CIBERES (CB06/06/0058), Madrid, Spain Medicine Department, School of Medicine, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: Emilio
authors.initials: E
authors.lastname: Bouza
authors.affiliation: Clinical Microbiology and Infectious Diseases, Hospital General Universitario Gregorio Marañón, Madrid, Spain Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain CIBER Enfermedades Respiratorias-CIBERES (CB06/06/0058), Madrid, Spain Medicine Department, School of Medicine, Universidad Complutense de Madrid, Madrid, Spain jguineaortega@yahoo.es.
authors.forename: Jesús
authors.initials: J
authors.lastname: Guinea
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology* / Q000627:therapeutic use; D018441:Biofilms / Q000187:drug effects*; D002176:Candida albicans / Q000187:drug effects* / Q000302:isolation & purification / Q000378:metabolism*; D058387:Candidemia / Q000188:drug therapy / Q000378:metabolism; D054714:Echinocandins / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D055666:Lipopeptides / Q000494:pharmacology* / Q000627:therapeutic use; D000077551:Micafungin
chemical_list: D000935:Antifungal Agents; D054714:Echinocandins; D055666:Lipopeptides; D000077551:Micafungin
keywords: C. albicans; XTT; antifungal activity; candidaemia; fungaemia