J Eur Acad Dermatol Venereol. 2021 Mar 24. doi: 10.1111/jdv.17240. Online ahead of print.
Nondermatophyte molds (NDM) onychomycosis is often difficult to diagnose as NDMs have been considered contaminants of nails. There are several diagnostic methods used to identify NDMs, however, repeated laboratory isolation at different time points is recommended to validate pathogenicity. With NDM and mixed infection (dermatophytes plus NDM) onychomycosis on the rise, accurate clinical diagnosis along with mycological tests are recommended. Systemic antifungal agents such as itraconazole and terbinafine (e.g. pulse regimen: 1 pulse = every day for one week, followed by no treatment for three weeks) have shown efficacy in treating onychomycosis caused by various NDM pathogens such as Aspergillus spp., Fusarium spp., Scopulariopsis brevicaulis, and Onychocola canadensis. Studies investigating topical therapy and devices for NDM onychomycosis treatment are limited. The emergence of antifungal resistance necessitates the incorporation of antifungal susceptibility testing into diagnosis, when possible, for the management of recalcitrant infections. Case studies documented in the literature show newer azoles such as posaconazole and voriconazole as sometimes effective in treating resistant NDM onychomycosis following determination of their minimum inhibitory concentration (MIC) values. Treatment with broad-spectrum antifungal agents (e.g. itraconazole and efinaconazole) and other combination therapy (oral+oral and/or oral+topical) may be considerations in the management of NDM onychomycosis.