title: Biofilm formation of the black yeast-like fungus Exophiala dermatitidis and its susceptibility to antiinfective agents.
abstract: Various fungi have the ability to colonize surfaces and to form biofilms. Fungal biofilm-associated infections are frequently refractory to targeted treatment because of resistance to antifungal drugs. One fungus that frequently colonises the respiratory tract of cystic fibrosis (CF) patients is the opportunistic black yeast-like fungus Exophiala dermatitidis. We investigated the biofilm-forming ability of E. dermatitidis and its susceptibility to various antiinfective agents and natural compounds. We tested 58 E. dermatitidis isolates with a biofilm assay based on crystal violet staining. In addition, we used three isolates to examine the antibiofilm activity of voriconazole, micafungin, colistin, farnesol, and the plant derivatives 1,2,3,4,6-penta-O-galloyl-b-D-glucopyranose (PGG) and epigallocatechin-3-gallate (EGCG) with an XTT reduction assay. We analysed the effect of the agents on cell to surface adhesion, biofilm formation, and the mature biofilm. The biofilms were also investigated by confocal laser scan microscopy. We found that E. dermatitidis builds biofilm in a strain-specific manner. Invasive E. dermatitidis isolates form most biomass in biofilm. The antiinfective agents and the natural compounds exhibited poor antibiofilm activity. The greatest impact of the compounds was detected when they were added prior cell adhesion. These findings suggest that prevention may be more effective than treatment of biofilm-associated E. dermatitidis infections.
authors.affiliation: Institute of Medical Microbiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
authors.forename: Lisa
authors.initials: L
authors.lastname: Kirchhoff
authors.affiliation: Institute of Medical Microbiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
authors.forename: Maike
authors.initials: M
authors.lastname: Olsowski
authors.affiliation: Institute of Medical Microbiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Zilmans
authors.affiliation: Institute of Medical Microbiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
authors.forename: Silke
authors.initials: S
authors.lastname: Dittmer
authors.affiliation: Institute of Medical Microbiology, Rheinisch-Westfälische Technische Hochschule Aachen University Hospital, Aachen, Germany.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Haase
authors.affiliation: Institute of Medical Microbiology and Hospital Epidemiology, Medical School Hannover (MHH), Hannover, Germany.
authors.forename: Ludwig
authors.initials: L
authors.lastname: Sedlacek
authors.affiliation: Institute for Experimental Virology, TWINCORE Centre for Experimental and Clinical Infection Research; a joint venture between the Medical School Hannover (MHH) and the Helmholtz Centre for Infection Research (HZI), Hannover, Germany.
authors.forename: Eike
authors.initials: E
authors.lastname: Steinmann
authors.affiliation: Institute of Medical Microbiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Buer
authors.affiliation: Institute of Medical Microbiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
authors.forename: Peter-Michael
authors.initials: PM
authors.lastname: Rath
authors.affiliation: Institute of Medical Microbiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
authors.forename: Joerg
authors.initials: J
authors.lastname: Steinmann
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D001422:Bacterial Adhesion / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D002392:Catechin / Q000031:analogs & derivatives / Q000494:pharmacology; D003091:Colistin / Q000494:pharmacology; D003550:Cystic Fibrosis / Q000150:complications* / Q000382:microbiology; D054714:Echinocandins / Q000494:pharmacology; D005093:Exophiala / Q000187:drug effects / Q000302:isolation & purification / Q000502:physiology*; D005204:Farnesol / Q000494:pharmacology; D006801:Humans; D055666:Lipopeptides / Q000494:pharmacology; D000077551:Micafungin; D008826:Microbial Sensitivity Tests; D009181:Mycoses / Q000382:microbiology*; D065819:Voriconazole / Q000494:pharmacology; D047071:beta-Glucans / Q000494:pharmacology
chemical_list: D000935:Antifungal Agents; D054714:Echinocandins; D055666:Lipopeptides; D047071:beta-Glucans; C069894:poly-1-6-glucopyranosyl-1-3-glucopyranose glucan; D005204:Farnesol; D002392:Catechin; C045651:epigallocatechin gallate; D065819:Voriconazole; D000077551:Micafungin; D003091:Colistin