Species diversity, antifungal susceptibility and phenotypic and genotypic characterisation of Exophiala spp. infecting patients in different medical centres in Brazil

• Published in: Mycoses 2017-05, Vol.60 (5), p.328-337
• Main Authors: Silva, Wendy C., Gonçalves, Sarah S., Santos, Daniel W. C. L., Padovan, Ana Carolina B., Bizerra, Fernando C., Melo, Analy S. A.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Amphotericin B; Amphotericin B - pharmacology; Antifungal agents; Antifungal Agents - pharmacology; antifungal susceptibility; Brazil - epidemiology; Caspofungin; Child; Child, Preschool; Clinical isolates; DNA, Ribosomal Spacer - genetics; Echinocandins - pharmacology; Electron microscopy; Exophiala; Exophiala - classification; Exophiala - drug effects; Exophiala - genetics; Exophiala - ultrastructure; Exophiala spp; Female; Fungi; Genetic Variation; Genotype; Humans; Itraconazole; Itraconazole - pharmacology; Lipopeptides - pharmacology; Male; Microbial Sensitivity Tests; Microscopy, Electron, Scanning; Middle Aged; Minimum inhibitory concentration; Phaeohyphomycosis - blood; Phaeohyphomycosis - epidemiology; Phaeohyphomycosis - microbiology; Phenotype; Posaconazole; Scanning electron microscopy; Species diversity; species identification; Terbinafine; Triazoles; Voriconazole
• ISSN: 0933-7407; 1439-0507
• DOI: 10.1111/myc.12597

Summary The Exophiala genus is responsible for many superficial and invasive infections resulting from black fungi. Identification of Exophiala at the species level is based on morphological observations complemented by molecular tests. The aim of this study was to identify 23 clinical isolates of Exophiala spp. and evaluate the antifungal susceptibility to seven different agents. Molecular identification was based on an analysis of ITS region of rDNA using genomic databases. The micromorphology was evaluated by microculture and scanning electron microscopy. The susceptibility tests were performed using the antifungal agents 5‐fluorocytosine (5‐FC), amphotericin B (AMB), itraconazole (ITC), voriconazole (VRC), posaconazole (PSC), caspofungin (CFG) and terbinafine (TRB). The ITS analysis identified 100% of the following isolates as: E. dermatitidis (8), E. xenobiotica (6), E. bergeri (4), E. oligosperma (3), E. spinifera (1) and E. mesophila (1). The antifungal susceptibility tests showed that the triazoles compounds were in vitro the most active agents against Exophiala. ITS sequencing enabled the accurate identification of the 23 tested isolates. The triazoles, particularly itraconazole and posaconazole, exhibited MIC values lower than AMB, CAS and 5‐FC. Although the guidelines do not indicate AMB for treatment against Exophiala spp., this study showed activity for all of the tested species, except E. mesophila.