Superficial Fungal Skin Infections

Common cause of skin infection, which may be misdiagnosed for other skin conditions, particularly eczema, contact dermatitis and bacterial infections. The 2 links under Internet and Further Reading below provide many illustrations to help with diagnosis when there is any uncertainty. There are two main types of superficial fungal infection:

• Dermatophytes, particularly Trichophyton rubrum, Trichophyton mentagrophytes, Trichophyton tonsurans and Epidermophyton floccosum.
• Yeasts, mainly Candida albicans

There are three main genera of fungi: Trichophyton, Mycrosporum, Epidermophyton. These are moulds, also known as 'ringworm' or 'tinea'. Dermatophytes can be transmitted from human to human. Humans can also catch animal ringworm, particularly Microsporum canis and Trichophyton verrucosum, from domestic animals. Names of infections are derived from the area infected:

• Tinea pedis: foot (athlete's foot): mainly occurs between the toes. Is either dry with scaling or moist with maceration, peeling and fissuring of toe webs. The skin is red and itchy, often presenting in late childhood or young adulthood:
  • Moccasin type: on soles, heels and lateral borders of feet. Erythema with minute papules on margin, fine white scaling, hyperkeratosis. Usually both feet are affected; is chronic with exacerbations. Susceptible to secondary infection, especially in people with diabetes and those who have undergone coronary by-pass surgery with harvesting of leg veins.
  • Inflammatory/bullous type: vesicles or blisters filled with clear fluid on sole, instep and between toes; may also lead to secondary bacterial infection.
  • Ulcerative type: interdigital; Tinea pedis extends onto dorsal and plantar foot, often with bacterial infection.
• Tinea manuum (hand):
  • Usually only affects the dominant hand and associated with Tinea pedis
  • Well-demarcated patches of scaling, hyperkeratosis especially on creases of palm
  • Often involves dorsa and sides of fingers
• Tinea cruris (groin):
  • Large well-demarcated plaques of scaling dull red/brown skin with possible papules or pustules at margin in groin and on thighs, with possible extension to buttocks
• Tinea corporis (body/trunk):
  • Sharply marginated plaques, scaling and/or with pustules or vesicles; enlarges from the edge with central clearing with concentric rings.
  • Usually single patch. Infection caught from animals are more inflamed with vesicles, crusting and blisters.
• Tinea facialis (face):
  • More common in children, mainly asymptomatic.
  • May present as well-demarcated macule or plaque of variable size with elevated border and central regression, minimal scaling usual.
  • Area pink to red and hyperpigmented in black patients.
  • Can affect any area of the skin but not usually symmetrical.
• Tinea incognito:
  • Occurs with infection of area treated with topical steroids.
  • Maybe asymptomatic or very itchy or even painful.
  • Skin deep red with follicular papules or pustules.
• Tinea unguum (nail):
  • Dermatophyte infection of hair shaft
  • Scalp or beard area; well circumscribed pruritic scaling area of hair loss, with variable inflammatory response
  • May cause extensive hair loss, skin atrophy leading to permanent alopecia, and scales on remaining hairs
  • Examination under Wood's light helps to confirm the diagnosis and establish causative organism

• Candidiasis:
  • Caused by yeast, usually Candida albicans. Common cause of infection to skin, mouth and vagina.
  • Usually occurs in moist, occluded sites e.g. under breasts, axillae, between buttocks. Also on hands between fingers and on feet, between toes.
  • In babies, presents as nappy dermatitis. Usually erythematous patches with small pustular lesions at the edges.
  • Angular cheilitis may be associated with Candida infection
• Pityriasis versicolor:
  • Is caused by an overgrowth of Malassezia furfur, which is part of the normal skin flora. Pityrosporon orbiculare, Pityrosporon ovale, and Malassezia ovalis are synonyms for M furfur.¹
  • Pityrosporum orbiculare and Pityrosporum ovale; cause Pityrosporum Folliculitis.
  • Often confused with acne vulgaris (but no comedones or cysts).
  • Is a chronic, asymptomatic condition, appearing as well demarked scaling patches of variable pigmentation, mainly found on the trunk.

• Diabetes mellitus
• Cushing's, corticosteroids
• Hodgkin's disease
• HIV infection
• Pregnancy
• Immunosuppressants or following a course of antibiotics

• Scraping for direct microscopy and culture; examination of skin scrapings are particularly important if systemic therapy is being considered or where there is doubt about the diagnosis.
• Examination with Wood's (UV) lamp - blue-green fluorescence of the scales (if patient hasn't bathed recently).
• Microscopy: If scale from Pityriasis versicolor is treated with KOH solution and heated, microscopy shows filamentous hyphae and round yeast forms called "spaghetti and meat balls".

Most localised fungal infections are treated with topical preparations. Systemic therapy may be necessary for nail or scalp infection or if the skin infection is widespread, disseminated or intractable².

Candidiasis

• Candidal skin infections:
  • May be treated with topical imidazole antifungals, e.g. clotrimazole, ketoconazole, miconazole; topical terbinafine is an alternative.
  • Topical application of nystatin is also effective for candidiasis but it is ineffective against dermatophytosis.
  • Refractory candidiasis requires systemic treatment, usually with fluconazole.
  • Systemic treatment with terbinafine is not appropriate for refractory candidiasis.
• Oropharyngeal candidiasis:
  • Usually responds to topical therapy with nystatin, amphotericin, or miconazole.
  • Fluconazole is effective for unresponsive infections. Itraconazole may be used for fluconazole-resistant infections.
• Angular cheilitis:
  • Nystatin ointment is used in the fissures of angular cheilitis when associated with Candida.
• Vaginal candidiasis (thrush):
  • May be treated with locally acting antifungals, with fluconazole given by mouth, or oral itraconazole for resistant organisms.

Dermatophytoses

• Scalp infection often requires systemic treatment but additional topical application of an antifungal may reduce the risk of transmission.
• Most other local ringworm infections can be treated with topical antifungal preparations (including shampoos, e.g. ketoconazole).
• The imidazole antifungals, e.g. clotrimazole, ketoconazole, miconazole, are all effective.
• Terbinafine cream is also effective but it is more expensive.
• Oral therapy is usually used for chronic conditions or when topical treatment has failed. Terbinafine is more effective than griseofulvin³.
• Antifungal powders are of little benefit and may cause skin irritation, but may have a role in preventing re-infection.
• Tinea infection of the nail:
  • Topical application of amorolfine or tioconazole may be effective for treating early onychomycosis but otherwise systemic therapy may be required (but not necessarily appropriate for just cosmetic purposes in view of cost).
  • Terbinafine and itraconazole have largely replaced griseofulvin for the systemic treatment of onychomycosis, particularly of the toenail; terbinafine is considered to be the drug of choice. Itraconazole can be administered as intermittent pulse therapy.
• Pityriasis versicolor:
  • May be treated with ketoconazole shampoo or selenium sulphide shampoo used as a lotion (diluted with water to reduce irritation).
  • Topical imidazole antifungals are alternatives but large quantities may be required. If topical therapy fails, or if the infection is widespread, pityriasis versicolor may require systemic treatment with itraconazole or fluconazole.
  • Relapse is common, especially in the immunocompromised.
• Compound topical preparations:
  • Combination of an imidazole and a mild corticosteroid (e.g. hydrocortisone 1%) may be of value in the treatment of eczematous intertrigo or a severely inflamed patch of ringworm.

Immunocompromised patients

• Immunocompromised patients are at particular risk of fungal infections and may receive antifungal drugs prophylactically; oral imidazole or triazole antifungals are the drugs of choice for prophylaxis.
• Fluconazole is better absorbed than itraconazole and ketoconazole, and is considered less toxic than ketoconazole for long-term use.
• Amphotericin by intravenous infusion is used for the empirical treatment of serious fungal infections. Fluconazole is used for treating Candida albicans infection.

• Often chronic and recurrent.