Common cutaneous dermatophyte infections of the skin and nails

André Marais,Elzbieta Osuch

doi:10.4102/safp.v59i3.4689

Abstract

Superficial fungal infections occur in approximately 20% of the population. Dermatophyte infections are mainly caused by organisms from the Trichophyton, Epidermophyton, and Microsporum genera, and should not be confused with infections caused by Candida sp. since management may differ. The diagnosis of cutaneous dermatophyte infections are confirmed with potassium hydroxide (KOH) preparations as clinical diagnosis is not always accurate, and may result in inappropriate treatment. Most dermatophyte infections are successfully managed with topical antifungal preparations; however, systemic therapy provides an increased cure rate and reduces re-occurrence. This review focuses on the most common dermatophyte infections seen by South African health-care providers and briefly describes the available treatment options, which may differ from agents used elsewhere in the world.

Highlights

It is estimated that 10 – 20% of the global population is affected by fungal skin infections at any given time.[1]
Pityriasis versicolor and pityriasis capitis caused by yeasts in the genus Malassezia are some of the well-known examples
Cutaneous mycosis extends deeper into the epidermal structures including the keratinized layers of the skin, hair and nails

Summary

Introduction

It is estimated that 10 – 20% of the global population is affected by fungal skin infections (mycosis) at any given time.[1]. Clinical prevalence patterns may vary, but it is estimated that approximately 25% of the global population is infected by the two most common causative pathogens namely Trichophyton rubum and Trichophyton interdigitale.[2] South African epidemiological studies report a 41% prevalence rate, non-symptomatic and occult infections contribute 10–15% of positive culture results.[3, 4] Predisposing factors are dependent on geographical location (customary in tropical countries), socioeconomic status (commonplace in crowded living conditions and close proximity to animals), environmental exposure (mundane in warm, humid conditions, people wearing occlusive shoes, the use of public swimming pools), cultural norms (double the infection rate in Muslim communities), and co-morbid diseases (typical in diabetics, HIV/AIDS and hyperhidrosis). Lesions present with wavering degrees of inflammation, depth of involvement, and varying sizes These lesions may be single or multiple, and the size generally ranges from 1 to 5 cm, but larger lesions may occur.[11] Clinically it presents as a pruritic, round often erythematous, scaling patch that heals centrally with a remaining raised red active border around the hypopigmented central area (Figure 2). Inflammation is reduced with wet compresses of Burow’s solution, and appropriate oral antibiotic therapy if secondary bacterial infection is present.[12,13,14]

Tinea capitis

Tinea unguium

Disruptors of fungal cell wall integrity and synthesis

Inhibitors of ergosterol synthesis and cell membrane function

Findings

Disruptors of intracellular metabolism