Tinea pedis (athlete's foot)

Introduction

Fungal infection of the feet.

Etiology

• general
  • Trichophyton rubrum (most common cause of chronic Tinea pedis)
  • Trichophyton mentagrophytes causes more inflammatory lesions
  • Aspergillus spp
• interdigital type
  • dermatophytes
    • Trichophyton mentagrophytes
    • Trichophyton rubrum
    • Epidermophyton floccosum
  • non-dermatophytes
    • Candida albicans
    • Scytalidium hyalinum
    • Hendersonula toruloidea
• moccasin type
  • Trichophyton rubrum
  • Epidermophyton floccosum
• vesicular, inflammatory or bullous
  • Trichophyton mentagrophytes
• ulcerative
  • Trichophyton mentagrophytes
  • Trichophyton rubrum
  • Epidermophyton floccosum
• predisposing factors:
  • hot, humid weather
  • occlusive footwear
  • excessive sweating
  • diabetes mellitus

Epidemiology

• most frequent form of cutaneous fungal infection
• males > females
• most common ages 20-50 years
• acquired by walking barefoot on contaminated floors

Clinical manifestations

• 3 common forms
  • interdigital
    • macerated, red & scaly toe web space
    • often associated with fissures
    • 4th web space is most commonly affected
  • moccasin type
    • dry, thick, scaly skin on soles & sides of feet
    • erythematous soles
    • may be seen on 2 feet & 1 hand, or 1 foot & 2 hands
    • case with fungal rash extending to include lateral malleolus
    • chronic form
  • vesicular, inflammatory or bullous
    • erythema, scaling & vesicles, usually of the instep
    • 1-2 mm vesicles may be very pruritus (acute form)
    • vesicles may coalesce into larger bullae
• less common forms
  • ulcerative
    • an extension of interdigital type into dermis due to maceration & secondary bacterial infection
• dermatophytid
  • vesicular eruption of the fingers &/or palmar aspects of the hands
  • inflammatory response
  • secondary bacterial infection may occur
• infection tends to be chronic with exacerbations in hot weather

* images

Laboratory

(see Tinea)

Complications

• may provide portal of entry for cellulitis or lymphangitis in patients with chronic leg edema, especially after harvesting of leg veins for CABG

Differential diagnosis

• plantar wart (no erythema, no maceration, plaque vs scaly, may be covered with callus)

Management

• topical imidazole compound for 4 weeks
  • effective in treating dermatophyte, Candida & Malassezia infection
  • clotrimazole# (Lotrimin AF)
  • miconazole# (Monistat, Lotrimin AF)
  • ketoconazole (Nizoral)
  • econazole (Spectazole)
  • sulconazole (Exelderm)
  • oxiconazole (Oxistat)
  • terconazole (Terazol)
  • butenafine* (Lotrimin Ultra)
  • terbinafine (Lamisil)
• topical povidone iodine (Betadine) for initial management of severe cases
• oral antifungals
  • griseofulvin (ultramicrosize) 250-375 mg BID for 4-8 weeks
  • fluconazole 150 mg/week for 4 weeks
  • itraconazole 100 mg/day for 4 weeks
• patient education
  • avoid occlusive footwear
  • wear shower shoes in public showers
  • high-temperature (>= 60 degrees C) laundering of socks is needed for eradication of Trichphyton rubrum & Aspergillus species causing Tinea pedis

* fungicidal agent

# fungistatic agent

More general terms

• Tinea