A case of onychomycosis caused by Aspergillus candidus

Abstract

Based on epidemiological studies, Aspergillus candidus has been demonstrated as an emerging fungal agent of toenail onychomycosis. Here we report a case of a toenail infection caused by A. candidus in a healthy 60-year-old woman. Based on macroscopic and microscopic characteristics of the culture as well as nucleotide sequencing of 28S region, the causative agent was identified as A. candidus.

Keywords: Aspergillus candidus; DNA sequencing; Onychomycosis.

Fig. 1

Clinical features of the toenail lesion caused by Aspergillus candidus. A total discolouration with a subungual hyperkeratosis is obviously observed.

Fig. 2

15% KOH slide preparation of the nail scraping showed rather broad septate and irregular hyphae (×400).

Fig. 3

Colony morphology of the causing agent of onychomycosis on Czapek Yeast Agar (CYA) after incubating at 25° C for 6 days. (a) The picture depicts a pale yellow colony. And the microscopic view of filaments after performing slide culture: (b) the fungus possesses white, typically globose, conidial heads producing globose or subglobose, smooth, thin-walled conidia with spherical vesicles and metulae cover the entire surface of the vesicle. (Scale bar: 2 μm.) (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.).

Fig. 4

After 72 h of incubation at 35 °C, it was found that the isolate was resistant to Caspofungin with MIC>32 μg/mL and moderately susceptible to Fluconazole with MIC 2 μg/mL. However it was susceptible to Posaconazole with MICs 0.032 μg/mL.