Mycological Considerations in the Topical Treatment of Superficial Fungal Infections

Abstract

Trichophyton rubrum remains the most common pathogenic dermatophyte in the United States, Europe, and industrialized Asia, although other species are predminant elsewhere. Candida albicans is the most common pathogenic yeast, with other species occasionally encountered. Just a few of the 14 described species of Malassezia cause pityriasis versicolor worldwide. FDA approval does not always accurately reflect the potential utility of any given topical antifungal agent. Azole, hydroxypyridone, and allylamine agents are beneficial in the management of dermatophytosis; however, the allylamines may lead to faster symptom resolution and a higher degree of sustained response. Although in actual clinical use the allylamines have all shown some activity against superficial cutaneous candidiasis and pityriasis versicolor, the azole agents remain drugs of choice. Ciclopirox is an excellent broad-spectrum antifungal agent. Optimal topical therapy for superficial fungal infections cannot yet be reliably based upon in-vitro laboratory determination of sensitivity. Inherent antibacterial and anti-inflammatory properties possessed by some antifungal agents may be exploited for clinical purposes. Candida species may be azole-insensitive due to efflux pumps or an altered target enzyme. So-called "antifungal resistance" of dermatophyets is actually due to poor patient adherence (either in dosing or treatment duration), or to reinfection.