Onychomycosis caused by Onychocola canadensis: the first report in Estonia and lessons to learn

A revision of malbranchea-like fungi from clinical specimens in the United States of America reveals unexpected novelty

The fungi of the order Onygenales can cause important human infections; however, their taxonomy and worldwide occurrence is still little known. We have studied and identified a representative number of clinical fungi belonging to that order from a reference laboratory in the USA. A total of 22 strains isolated from respiratory tract (40%) and human skin and nails (27.2%) showed a malbranchea-like morphology. Six genera were phenotypically and molecularly identified, i.e. Auxarthron/Malbranchea (68.2%), Arachnomyces (9.1%), Spiromastigoides (9.1%), and Currahmyces (4.5%), and two newly proposed genera (4.5% each). Based on the results of the phylogenetic study, we synonymized Auxarthron with Malbranchea, and erected two new genera: Pseudoarthropsis and Pseudomalbranchea. New species proposed are: Arachnomyces bostrychodes, A. graciliformis, Currahmyces sparsispora, Malbranchea gymnoascoides, M. multiseptata, M. stricta, Pseudoarthropsis crassispora, Pseudomalbranchea gemmata, and Spiromastigoides geomycoides, along with a new combination for Malbranchea gypsea. The echinocandins showed the highest in vitro antifungal activity against the studied isolates, followed by terbinafine and posaconazole; in contrast, amphotericin B, fluconazole, itraconazole and 5-fluorocytosine were less active or lacked in vitro activity against these fungi.

[Onychocola canadensis Sigler in onychomycosis : A new dermatophyte-like mould in Germany]

Moulds or non-dermatophyte moulds (NDM) are being increasingly isolated as causative agent of onychomycoses. Known causes of a NDM-OM are Scopulariopsis brevicaulis, Fusarium, Aspergillus, Acremonium, Neoscytalidium dimidiatum, Arthrographis kalrae, and Chaetomium. In this article, 5 patients with suspected nail infection due to Onychocola canadensis are reported for the first time in Germany. Systemic antifungal agents are not considered to be effective in NDM onychomycosis. In individual cases, however, terbinafine seems to be effective in Onychocola canadensis infection of the nails. Treatment of choice represents, however, nontraumatic nail avulsion using 40 % urea ointment followed by antifungal nail lacquer with ciclopirox olamine or amorolfine.