The first case of onychomycosis in a koala (Phascolarctos cinereus) due to atypical isolates of Microsporum gypseum, a diagnostic challenge

Background & Superficial mycotic infections have been only poorly described in koalas and there are no reliable mycologically confirmed data regarding clinical isolation of dermatophytes in this animal.
We report of an 11-year-old female koala, kept in a zoo in Tokyo, Japan, and presenting with hyperkeratotic lesions and scaly plaques on forepaw claws and pads reminiscent of fungal infection. Direct microscopy of the scrapings was indicative of a dermatophyte infection. By culture and subsequent repeated subculturing of clinical specimens on Sabouraud dextrose agar, Mycobiotic agar, and Potato dextrose agar, two distinct strains with different colony morphotypes (designed as types I and II) were identified. Macro- and microscopic characteristics of the strains were suggestive of three different species, i.e. Microsporum canis, M. gypseum, and M. fulvum. However, partial sequencing of ITS-rRNA, translation elongation factor 1-α (Tef-1α), and beta tubulin (BT2) genes confirmed the identity of both isolates as M. gypseum. The animal was treated using a continuous terbinafine regimen, 250 mg/kg once daily for 12 weeks.
Disscusion: As far as we know this is the first proven case of dermatophytosis in a koala. The genetics underlying the variety of phenotypic traits in most classical dermatophyte species are unknown and more studies are needed to understand this phenomenon.