Fungal Infection

Definition/diagnostic criteria Fungal infections, or mycoses, are conditions caused by the invasion of the skin, hair or nails by fungi, which include yeasts and moulds. They range from superficial, localised skin conditions to deeper tissue infections and serious lung, blood or systemic diseases.

Fungal infections are broadly classified into superficial and systemic mycoses, depending on the degree and site of infection. Diagnosis is typically confirmed where necessary through direct microscopic examination of skin scrapings, nail clippings or plucked hair submerged in a potassium hydroxide (KOH) solution, culture tests, and, in some cases, histopathological examinations.

Epidemiology In the UK, fungal skin infections are common community problems. Conditions such as athlete’s foot (tinea pedis), jock itch (tinea cruris) and ringworm (tinea corporis) are widespread. Factors such as communal showers, certain occupations and lifestyles can increase the risk of contracting a fungal infection. Systemic mycoses are less common but can be serious, especially in immunocompromised individuals.

Diagnosis
Clinical features: Superficial infections present with symptoms including itching, scaling and redness. Nails may become thickened, discoloured and brittle in onychomycosis. Systemic infections may present with fever, cough and weight loss, among other symptoms, depending on the organ affected.

Investigations: Diagnosis is primarily clinical, supported by skin scrapings or nail clippings examined under KOH, which reveal fungal elements. Culture helps identify the specific fungus.

For systemic infections, blood tests, imaging and possibly biopsies may be indicated. Typical abnormalities found include hyphae in skin lesions, yeast cells in mucosal scrapings, and elevated inflammatory markers in systemic infections.

Treatment: Treatment depends on the type and severity of the fungal infection. For superficial mycoses, topical antifungals like clotrimazole or miconazole are usually sufficient. Oral antifungals, such as terbinafine or fluconazole, may be necessary for more extensive infection or onychomycosis.

For systemic infections, long-term oral or intravenous antifungals like amphotericin B, itraconazole or voriconazole are used. Treatment duration varies from weeks to months, depending on the infection’s location and severity.

Prognosis The prognosis for superficial fungal infections is generally good with appropriate treatment. Recurrence is common, especially if predisposing factors are not addressed. Systemic infections carry a more guarded prognosis, significantly if diagnosed late or in immunocompromised individuals. Continuous monitoring and long-term antifungal therapy may be required for chronic or recurrent cases.