Conflict of interest: none declared.
Clinical dermatology • Original article
A rationale for systemic treatment in onychomycosis with negative results on fungal examination
Article first published online: 30 MAY 2011
© The Author(s). CED © 2011 British Association of Dermatologists
Clinical and Experimental Dermatology
Volume 36, Issue 7, pages 724–727, October 2011
How to Cite
Amichai, B., Davidovici, B., Trau, H., Lyakhovitsky, A., Grunwald, M. H. and Shemer, A. (2011), A rationale for systemic treatment in onychomycosis with negative results on fungal examination. Clinical and Experimental Dermatology, 36: 724–727. doi: 10.1111/j.1365-2230.2011.04082.x
- Issue published online: 20 SEP 2011
- Article first published online: 30 MAY 2011
- Accepted for publication 6 February 2011
Background. Fungal infection of the nail affects millions of people worldwide, and has an estimated prevalence of about 10% of the general population. Laboratory confirmation of fungal infection is currently accepted as a requirement before initiation of antifungal treatment in clinical practice.
Aim. To examine the rationale for systemic treatment in cases of clinical onychomycosis with negative results on fungal examination (potassium hydroxide test and fungal culture).
Methods. In total, 147 patients with suspected clinical toenail onychomycosis but with negative results on fungal examination underwent up to three consecutive fungal examinations of the affected nails. Patients who were negative after these examinations underwent a fourth set of investigations, including PCR.
Results. Of the 147 cases initially thought to be negative, 138 (94%) were rated as positive after up to four consecutive sets of laboratory mycological investigations including PCR. Trichophyton rubrum was by far the commonest dermatophyte cultured from all samples.
Conclusions. In the majority of cases of initially negative examinations, consecutive laboratory fungal tests will eventually produce positive results. These findings suggest that systemic antifungal treatment should be started in patients with suspected fungal infections, even if they have negative laboratory fungal examinations.