title: Multiple species of Trichosporon produce biofilms highly resistant to triazoles and amphotericin B.
abstract: Invasive infections caused by Trichosporon spp. have increased considerably in recent years, especially in neutropenic and critically ill patients using catheters and antibiotics. The genus presents limited sensitivity to different antifungal agents, but triazoles are the first choice for treatment. Here, we investigated the biofilm production and antifungal susceptibility to triazoles and amphotericin B of 54 Trichosporon spp. isolates obtained from blood samples (19), urine (20) and superficial mycosis (15). All isolates and 7 reference strains were identified by sequence analysis and phylogenetic inferences of the IGS1 region of the rDNA. Biofilms were grown on 96-well plates and quantitation was performed using crystal violet staining, complemented with Scanning Electron Microscopy (SEM). Susceptibility tests for fluconazole, itraconazole, voriconazole and amphotericin B were processed using the microdilution broth method (CLSI) for planktonic cells and XTT reduction assay for biofilm-forming cells. Our results showed that T. asahii was the most frequent species identified (66.7%), followed by T. faecale (11.1%), T. asteroides (9.3%), T. inkin (7.4%), T. dermatis (3.7%) and one T. coremiiforme (1.8%). We identified 4 genotypes within T. asahii isolates (G1, G3, G4 and G5) and 2 genotypes within T. faecale (G1 and G3). All species exhibited high adhesion and biofilm formation capabilities, mainly T. inkin, T. asteroides and T. faecale. Microscopy images of high biofilm-producing isolates showed that T. asahii presented mainly hyphae and arthroconidia, whereas T. asteroides exhibited mainly short arthroconidia and few filaments. Voriconazole exhibited the best in vitro activity against all species tested. Biofilm-forming cells of isolates and reference strains were highly resistant to all antifungals tested. We concluded that levels of biofilm formation by Trichosporon spp. were similar or even greater than those described for the Candida genus. Biofilm-forming cells were at least 1,000 times more resistant to antifungals than planktonic cells, especially to voriconazole.
authors.affiliation: Laboratório Especial de Micologia, Disciplina de Infectologia, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Isabel Antonieta
authors.initials: IA
authors.lastname: Iturrieta-González
authors.affiliation: Laboratório Especial de Micologia, Disciplina de Infectologia, Universidade Federal de São Paulo, São Paulo, SP, Brazil; Departamento de Microbiologia e Imunologia, Instituto de Ciências Biomédicas, Universidade Federal de Alfenas, Alfenas, MG, Brazil.
authors.forename: Ana Carolina Barbosa
authors.initials: AC
authors.lastname: Padovan
authors.affiliation: Laboratório Especial de Micologia, Disciplina de Infectologia, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Fernando César
authors.initials: FC
authors.lastname: Bizerra
authors.affiliation: Laboratório de Micologia, Faculdade de Medicina, Universidade Federal do Mato Grosso, Cuiabá, MT, Brazil.
authors.forename: Rosane Christine
authors.initials: RC
authors.lastname: Hahn
authors.affiliation: Laboratório Especial de Micologia, Disciplina de Infectologia, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
authors.forename: Arnaldo Lopes
authors.initials: AL
authors.lastname: Colombo
mesh_terms: D000666:Amphotericin B / Q000494:pharmacology*; D000935:Antifungal Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D001769:Blood / Q000382:microbiology; D001938:Brazil; D004275:DNA, Ribosomal; D025141:Drug Resistance, Fungal / Q000187:drug effects; D006801:Humans; D008826:Microbial Sensitivity Tests; D008855:Microscopy, Electron, Scanning; D014230:Triazoles / Q000494:pharmacology; D014250:Trichosporon / Q000187:drug effects* / Q000302:isolation & purification / Q000502:physiology; D060586:Trichosporonosis / Q000382:microbiology; D014556:Urine / Q000382:microbiology
chemical_list: D000935:Antifungal Agents; D004275:DNA, Ribosomal; D014230:Triazoles; D000666:Amphotericin B