Tinea Pedis
Also known as: Tinea Manuum, Athlete's Foot
Tinea pedis is dermatophyte infection of the soles, interdigital spaces and sides of the feet. It is the commonest dermatophytosis of adults, affects roughly 10 to 15 percent of the population at any one time, and is rare before puberty. Tinea manuum is the corresponding infection of the palms and interdigital spaces of the hands. It nearly always accompanies tinea pedis and is usually acquired from the feet by autoinoculation.
Tinea pedis is clinically important beyond itch. It is the reservoir for onychomycosis, tinea cruris and tinea corporis, and a portal of entry for streptococcal cellulitis, particularly in diabetes and after saphenous vein harvest.
| Organism | Typical pattern |
|---|---|
| Trichophyton rubrum | Commonest; chronic interdigital and moccasin disease; tinea manuum |
| Trichophyton interdigitale | Vesiculobullous and interdigital disease; more inflammatory |
| Epidermophyton floccosum | Interdigital disease; communal outbreaks |
| Trichophyton mentagrophytes (zoophilic) | Occasional inflammatory disease |
| Trichophyton tonsurans | Occasional, linked to scalp disease and contact sport |
| Trichophyton indotineae | Reported in extensive disease; terbinafine resistant |
Arthroconidia are shed in scale and persist for months on floors and surfaces in swimming pools, communal showers, changing rooms, mosques, hostels and military accommodation. Infection follows walking barefoot on contaminated floors, shared footwear and shared towels.
Risk factors: occlusive footwear, sweating, age, communal bathing, diabetes mellitus, peripheral arterial disease, immunosuppression, family history, HIV, and the presence of onychomycosis or tinea pedis in a household member.
Tinea pedis is uncommon in populations that go barefoot or wear open sandals, and common where closed, occlusive footwear is worn. Footwear, not skin type, accounts for the geographical difference.
| Pattern | Typical organism | Features |
|---|---|---|
| Interdigital (intertriginous) | Trichophyton rubrum, Trichophyton interdigitale, Epidermophyton floccosum | White, macerated, sodden scale, fissures and erosions in the web spaces, usually the third and fourth; itch; may spread to the sole and toes |
| Moccasin (chronic hyperkeratotic) | Trichophyton rubrum | Diffuse erythema and fine silvery scale over the sole, lateral border and heel in a moccasin distribution; mild itch; often unilateral at first; commonly accompanied by onychomycosis |
| Vesiculobullous (inflammatory) | Trichophyton interdigitale | Tense vesicles and bullae on the arch, instep and sides of the foot; intense itch; may flare with secondary bacterial infection or precipitate cellulitis |
| Acute ulcerative | Dermatophyte with gram negative bacteria | Macerated, purulent, foul smelling erosions and ulcers in the web spaces, with spread across the foot; associated with Pseudomonas aeruginosa and other gram negative bacilli |
Dermatophytosis complex describes a mixed fungal and bacterial infection of the toe webs in which bacteria cause maceration, odour and erosion, and dermatophyte persistence causes recurrence if only the bacteria are treated.
- Dry, diffuse hyperkeratosis and scale of the palm, accentuated in the palmar creases, with little or no inflammation, usually on one hand.
- The classic association is the one hand, two feet pattern: unilateral hand disease with bilateral moccasin tinea pedis.
- Vesicular or annular lesions of the dorsal hand, fingers and interdigital spaces.
- Fingernail involvement and onychomycosis of the affected hand.
- Autoinoculation by scratching the feet.
- Bilateral, symmetrical palmar involvement rarely represents tinea.
- In patients who handle animals, zoophilic species cause inflammatory vesicular tinea manuum.
- Bacterial cellulitis and lymphangitis: fissured, macerated web spaces allow entry of group A streptococci and Staphylococcus aureus. Recurrent leg cellulitis is an indication to examine and treat the toe webs.
- Diabetic foot disease: fissures and erosions become ulcers in the presence of neuropathy and ischaemia, and antifungal treatment of the toe webs is part of foot care.
- Dermatophytid (id) reaction: a sterile vesicular eruption on the palms and sides of the fingers, in response to circulating antigen from an acute inflammatory focus on the foot, with no fungal elements in the id lesions. It settles when the foot infection is controlled.
- Onychomycosis: direct spread to the nail bed.
- Spread: to the groin and trunk through towels, clothing and hands.
- Chronic leg oedema and lymphatic damage: after repeated cellulitis.
| Condition | Discriminating features |
|---|---|
| Contact dermatitis (footwear, rubber chemicals, topical agents) | Distribution follows contact with the shoe; dorsum of the toes; sparing of the web spaces |
| Dyshidrotic eczema (pompholyx) | Deep vesicles on the palms, soles and sides of fingers, bilateral and symmetrical |
| Atopic dermatitis and juvenile plantar dermatosis | Children; forefoot; glazed, fissured skin; atopy |
| Psoriasis (palmoplantar) | Sharply demarcated scaly plaques, bilateral, nail pitting and psoriasis elsewhere |
| Palmoplantar pustulosis | Sterile pustules in crops, bilateral |
| Erythrasma (interdigital) | Coral red fluorescence; maceration without active edge |
| Candidal intertrigo of the toe webs or fingers | Moist, erosive, in wet working hands; yeasts on KOH |
| Pitted keratolysis | Malodorous, discrete crateriform pits on the pressure bearing sole; bacterial |
| Scabies | Burrows, sparing of fixed distribution, household itch |
| Keratoderma | Inherited or acquired, diffuse, bilateral, KOH negative |
| Secondary syphilis | Copper red scaly macules on palms and soles; serology positive |
| Bullous impetigo | Bullae, crusts and culture growing Staphylococcus aureus |
- Specimen: scale from the edge of a lesion or the roof of a vesicle, and material from between the toes. Hyperkeratotic scale is cleared in potassium hydroxide with dimethyl sulphoxide.
- Potassium hydroxide preparation: septate, branching hyphae and arthroconidia. Calcofluor white improves sensitivity.
- Culture: indicated for extensive or recurrent disease, before oral treatment, and in doubtful cases. Moccasin disease and onychomycosis give a higher yield.
- Bacterial culture: a swab from macerated or purulent webs, because gram negative bacteria change management.
- Histopathology: hyphae in the stratum corneum on periodic acid Schiff, with the sandwich sign.
- Nail inspection: nails are examined in every patient with tinea pedis.
Topical therapy
| Agent | Regimen |
|---|---|
| Terbinafine 1 percent cream | Twice daily for 1 week in interdigital disease; twice daily for 2 weeks in plantar disease |
| Naftifine 1 percent cream | Once daily for 2 weeks |
| Butenafine 1 percent cream | Once daily for 4 weeks, or twice daily for 1 week |
| Luliconazole 1 percent cream | Once daily for 2 weeks |
| Clotrimazole 1 percent cream | Twice daily for 4 weeks |
| Miconazole 2 percent cream | Twice daily for 4 weeks |
| Econazole 1 percent cream | Once daily for 4 weeks |
| Ketoconazole 2 percent cream | Once daily for 6 weeks |
| Sertaconazole 2 percent cream | Twice daily for 4 weeks |
| Ciclopirox 0.77 percent cream | Twice daily for 4 weeks |
| Tolnaftate 1 percent cream | Twice daily for 4 weeks |
Allylamines and butenafine give higher cure rates in shorter courses than azoles. Treatment is applied to the whole foot, including the sole and sides and not only the visible lesions, and continued for 1 to 2 weeks beyond clinical clearance. Hyperkeratotic disease responds poorly to topical therapy alone. A keratolytic (salicylic acid 6 percent, or urea 10 to 20 percent) is added, and oral therapy is usually needed.
Oral therapy
Oral therapy is for moccasin disease, extensive or hyperkeratotic disease, recurrent disease, tinea manuum, failure of topical therapy, onychomycosis, diabetes, and immunosuppression.
| Agent | Adult dose | Duration |
|---|---|---|
| Terbinafine | 250 mg once daily | 2 weeks for interdigital disease; 2 to 6 weeks for moccasin disease |
| Itraconazole | 200 mg twice daily, or 100 mg once daily | 1 week at 200 mg twice daily; 4 weeks at 100 mg daily |
| Fluconazole | 150 mg once weekly | 2 to 6 weeks |
| Griseofulvin (microsize) | 500 mg to 1 g daily | 4 to 8 weeks; lowest cure rate and highest relapse |
Specific situations
- Vesiculobullous disease: drying soaks (aluminium acetate 1 in 40, or potassium permanganate 1 in 10 000) for 15 to 20 minutes two to three times a day until vesicles dry, followed by an antifungal. A brief course of a topical corticosteroid may relieve severe inflammation, but only together with antifungal therapy.
- Bacterial superinfection: a topical or oral antibacterial effective against Staphylococcus aureus, streptococci and, in macerated webs, gram negative bacteria, according to culture. Ciprofloxacin is used when Pseudomonas aeruginosa is cultured from the toe webs.
- Cellulitis: treated with an oral or intravenous antibacterial, with the toe webs treated antifungally at the same time. Recurrent cellulitis needs long term control of tinea pedis.
- Diabetes and peripheral arterial disease: treated promptly, with foot examination at each visit.
- Tinea manuum: oral terbinafine 250 mg once daily for 2 to 6 weeks for hyperkeratotic disease, with a topical keratolytic and antifungal.
- Id reaction: treat the foot infection, with cool compresses and a topical corticosteroid for the id lesions.
- Pregnancy and breastfeeding: topical clotrimazole, miconazole or terbinafine. Oral agents are avoided unless the benefit outweighs the risk.
- Dry the feet and web spaces after bathing and swimming.
- Cotton or moisture wicking socks, changed daily and when damp.
- Rotate shoes, allow them to dry for 24 hours, and use an antifungal powder or spray in them.
- Wear sandals in communal showers, changing rooms and pool areas.
- Treat all affected sites together (feet, hands, nails, groin), and treat household members who are infected.
- Do not share towels, socks or footwear.
- Continue an antifungal powder or cream to the feet after clearance in recurrent disease.
