Genetic diversity of Aspergillus species isolated from onychomycosis and Aspergillus hongkongensis sp. nov., with implications to antifungal susceptibility testing

Abstract

Thirteen <i>Aspergillus</i> isolates recovered from nails of 13 patients (fingernails, n = 2; toenails, n = 11) with onychomycosis were characterized. Twelve strains were identified by multilocus sequencing as <i>Aspergillus</i> spp. (<i>Aspergillus sydowii</i> [n = 4], <i>Aspergillus welwitschiae</i> [n = 3], <i>Aspergillus terreus</i> [n = 2], <i>Aspergillus flavus</i> [n = 1], <i>Aspergillus tubingensis</i> [n = 1], and <i>Aspergillus unguis</i> [n = 1]). Isolates of <i>A. terreus</i>, <i>A. flavus</i>, and <i>A. unguis</i> were also identifiable by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The 13th isolate (HKU49<font size=-1>^T</font>) possessed unique morphological characteristics different from other <i>Aspergillus</i> spp. Molecular characterization also unambiguously showed that HKU49<font size=-1>^T</font> was distinct from other <i>Aspergillus</i> spp. We propose the novel species <i>Aspergillus hongkongensis</i> to describe this previously unknown fungus. Antifungal susceptibility testing showed most <i>Aspergillus</i> isolates had low MICs against itraconazole and voriconazole, but all <i>Aspergillus</i> isolates had high MICs against fluconazole. A diverse spectrum of <i>Aspergillus</i> species is associated with onychomycosis. Itraconazole and voriconazole are probably better drug options for <i>Aspergillus</i> onychomycosis.