title: Comparison of the antifungal activity of micafungin and amphotericin B against Candida tropicalis biofilms.
abstract: Candida tropicalis is the fourth most common cause of candidaemia in hospitalized patients and associated mortality is high. C. tropicalis frequently causes biofilm-related infections. Echinocandins and amphotericin B show potent in vitro activity against C. albicans biofilms, but their activity against C. tropicalis biofilms has received little attention.
  
  
  
  We studied production of biofilm by 54 C. tropicalis isolates from blood and the antifungal susceptibility of these isolates to micafungin, amphotericin B and liposomal amphotericin B. Biofilm production was measured using the crystal violet assay to determine biomass and the XTT reduction assay to determine metabolic activity. The antifungal susceptibility of planktonic and sessile cells was measured using the EUCAST EDef 7.2 procedure and XTT reduction assay, respectively. The sessile MIC endpoint of SMIC80 was defined as an 80% reduction in the metabolic activity of the biofilm treated with the antifungal compared with the control well.
  
  
  
  The three drugs were very active against the isolates in planktonic form, with micafungin showing the highest activity (P < 0.001). Micafungin was the most active agent against C. tropicalis biofilms (P < 0.001). In contrast, liposomal amphotericin B showed poor antifungal activity.
  
  
  
  Micafungin was the most active drug against C. tropicalis biofilm. Although the echinocandins and liposomal amphotericin B are considered very active against Candida spp. biofilms, this is not true for C. tropicalis, as liposomal amphotericin B showed poor antifungal activity against biofilms.
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 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: D000666:Amphotericin B / Q000494:pharmacology*; D000935:Antifungal Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D018533:Biomass; D041022:Candida tropicalis / Q000187:drug effects* / Q000302:isolation & purification / Q000502:physiology; D058387:Candidemia / Q000382:microbiology; D054714:Echinocandins / Q000494:pharmacology*; D005562:Formazans / Q000032:analysis; D005840:Gentian Violet / Q000032:analysis; D006801:Humans; D055666:Lipopeptides / Q000494:pharmacology*; D000077551:Micafungin; D008826:Microbial Sensitivity Tests; D013194:Staining and Labeling; D013778:Tetrazolium Salts / Q000378:metabolism
chemical_list: D000935:Antifungal Agents; D054714:Echinocandins; D005562:Formazans; D055666:Lipopeptides; D013778:Tetrazolium Salts; C059087:2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-((phenylamino)carbonyl)-2H-tetrazolium hydroxide; C059088:1,5-bis(2-methoxy-4-nitro-5-sulfophenyl)-3-((phenylamino)carbonyl)formazan; D000666:Amphotericin B; D005840:Gentian Violet; D000077551:Micafungin