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European Journal of Dermatology

A new agent of onychomycosis in the elderly: Onychocola canadensis Volume 7, issue 2, March 1997

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  • Author(s): N. Contet-Audonneau, J.-L. Schmutz, A.-M. Basile, C. de Bièvre , Mycological Laboratory, School of Medicine (Pr. G. Percebois), BP 184, 54505 Vandœuvre-les-Nancy Cedex, France.
  • Key words: antifungals, elderly, nail biopsy, Onychocola, onychomycosis, leg ulcer.
  • Page(s) : 115-7
  • Published in: 2000

Onychocola canadensis is an agent of onychomycosis which has recently been identified in Canada, New Zealand and more recently in France. We report on the observations of 5 patients living in the East of France who have never travelled to any foreign countries. Onychocola canadensis was isolated in abundance from toenails in 4 out of 5 cases (one case associated with Candida ciferrii). Most of the patients affected were elderly, a majority of them female who had varicose terrain. In all cases it was noted that the nails were yellowish, slightly hyperkeratotic and very friable. Moreover, the infection frequently attacked all the toenails. In one case, Onychocola canadensis was also isolated from a dry and hyperkeratotic intertrigo of the feet. In all cases, direct microscopic examinations were positive and revealed small spores, 2-3 mm wide. They were associated with hyaline hyphae of varying widths. Four nail biopsies showed fungal elements with certain characteristics: small spores and fine filaments with boring hyphae. As with dermatophytes, the strains of Onychocola canadensis were resistant to cycloheximide and were urease positive. We discovered that they turned rose-violet in a tetrazolium medium. Sensitivity to antifungal substances was tested (griseofulvine, cyclopiroxolamine, amorolfine, terbinafine and ketoconazole). Onychocola canadensis is probably underestimated as an agent of onychomycosis because of the slow growth of the fungi in culture and the necessity for a subculture for identification.