title: Keratitis-associated fungi form biofilms with reduced antifungal drug susceptibility.
abstract: OBJECTIVE
  To investigate the biofilm-forming capacity of Fusarium solani, Cladosporium sphaerospermum, and Acremonium implicatum, and the activities of antifungal agents against the three keratitis-associated fungi.
  
  
  METHODS
  The architecture of biofilms was analyzed using scanning electron microscopy and confocal scanning laser microscopy (CSLM). Susceptibility against six antifungal drugs was measured using the CLSI M38-A method and XTT reduction assay.
  
  
  RESULTS
  Time course analyses of CSLM revealed that biofilm formation occurred in an organized fashion through four distinct developmental phases: adhesion, germling formation, microcolony formation, and biofilm maturation. Scanning electron microscopy revealed that mature biofilms displayed a complex three-dimensional structure, consisting of coordinated network of hyphal structures glued by the extracellular matrix (ECM). The antifungal susceptibility testing demonstrated a time-dependent decrease in efficacy for all six antifungal agents as the complexity of fungal hyphal structures developed. Natamycin (NAT), amphotericin B (AMB), and NAT were the most effective against F. solani, C. sphaerospermum, and A. implicatum biofilm, respectively.
  
  
  CONCLUSIONS
  Corneal isolates of F. solani, C. sphaerospermum, and A. implicatum could produce biofilms that were resistant to antifungal agents in vitro.
authors.affiliation: Department of Ocular Microbiology, Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital University of Medical Science, Beijing, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Zhang
authors.forename: Xuguang
authors.initials: X
authors.lastname: Sun
authors.forename: Zhiqun
authors.initials: Z
authors.lastname: Wang
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Wenbo
authors.initials: W
authors.lastname: Hou
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D003315:Cornea / Q000382:microbiology* / Q000473:pathology; D015821:Eye Infections, Fungal / Q000188:drug therapy / Q000382:microbiology* / Q000473:pathology; D005658:Fungi / Q000502:physiology*; D006801:Humans; D007634:Keratitis / Q000188:drug therapy / Q000382:microbiology* / Q000473:pathology; D008826:Microbial Sensitivity Tests / Q000379:methods*; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning
chemical_list: D000935:Antifungal Agents