[Fungi causing onychomycoses in The Netherlands].

OBJECTIVE

To obtain information about prevalences of fungi responsible for onychomycosis in the Netherlands.

DESIGN

Retrospective.

SETTING

Mycological laboratory of the Dermatological department, University Hospital, Leiden, the Netherlands.

METHODS

The results of mycological tests of nail samples collected in the period of 1987-1992 were analysed. If the culture was positive, the nature of the yeast or dermatophyte was determined.

RESULTS

Nail samples were obtained from 861 patients (22% fingernails, 78% toenails). No mycological confirmation of clinical diagnosis could be obtained in 60% of fingernail samples and 45% of toenail samples. Of the mycologically confirmed finger onychomycoses 77.5% were caused by yeasts, the remaining part by Trichophyton rubrum. Toenail onychomycosis in 9.9% of the cases was caused by yeasts, in 11.8% by T. mentagrophytes, in 1.2% by Epidermophyton floccosum, and in under 1% by non-dermatophytes. Just as in fingernail onychomycosis, the major cause of toenail onychomycosis is T. rubrum.

CONCLUSION

Onychomycosis cannot be diagnosed on clinical grounds, without mycological testing. Since antimycotic treatment is not always effective in onychomycosis caused by yeasts and non-dermatophytes, mycological diagnosis is necessary.