Differentiating the Dermatophytes

Extract

Dermatophytosis is one of the most common communicable diseases in the world.¹ Dermatophytes are fungi whose primary sites of infection are hair, skin, and nails.² The identification of dermatophytes is clinically important because of the various infections that they can cause.³ Among some of the more common and difficult diseases are Tinea capitis, Tinea unguium, Tinea barbae, and Tinea pedis.

Tinea capitis is a form of ringworm that most commonly infects the scalp. It can cause ulcers on the scalp of the patient and loss of hair. Tinea unguium is a form of ringworm that most commonly infects fingernails and toenails. It can cause the patient's nail to become brittle, cracked, and crumbly. Tinea barbae is an infection of the bearded area of the face and neck of adult males. It can cause lesions with severe inflammation and extensive hair loss. Tinea pedis is the most common dermatophyte infection and infects the feet. It can cause the affected area of the feet to become pruritic with peeling of the foot tissue.

Since dermatophytes only invade the keratinized layers of hair, skin, and nails, clinical material must be obtained properly and can be sent to the laboratory for culture and direct examination. Direct examination of clinical material from patients with dermatomycosis can aid in the diagnosis and treatment of the patient.⁴ A piece of the clinical material from a patient can be observed in a potassium hydroxide (KOH) preparation at the same time it is cultured. If hyphae are seen in…

ABBREVIATIONS: KOH = potassium hydroxide; PDA = potato-dextrose agar.