Dermatophytes PDF

Dermatophytes Dr. Marwa Tariq Ahmed Department of medical microbiology T.U.C.O.M.  Dermatophytes Dermatophytes are fungi that require keratin for growth. Can cause superficial infections of the skin, hair, and nails. Dermatophytes are spread by...

Dermatophytes Dr. Marwa Tariq Ahmed Department of medical microbiology T.U.C.O.M.  Dermatophytes Dermatophytes are fungi that require keratin for growth. Can cause superficial infections of the skin, hair, and nails. Dermatophytes are spread by direct contact from other people (anthropophilic organisms), animals (zoophilic organisms), and soil (geophilic organisms), as well as indirectly from fomites. Dermatophyte infections can be readily diagnosed based on the history, physical examination, and potassium hydroxide (KOH) microscopy. Diagnosis occasionally requires fungal culture or histologic examination.  About 40 types of fungus can cause ringworm. They are typically of the Trichophyton, Microsporum, or Epidermophyton type. Risk factors include using public showers, contact sports such as wrestling, excessive sweating, contact with animals, obesity, and poor immune function. Ringworm can spread from other animals or between people.  Tinea Capitis Infection of the scalp and hair shafts. Most common in children. Transmission is fostered by poor hygiene and overcrowding, and contaminated hats, brushes, pillowcases, and other inanimate objects. Characterized by irregular or well-demarcated alopecia and scaling. When swollen hairs fracture a few millimeters from the scalp, “black dot” alopecia is produced.  Tinea Corporis Tinea corporis, or ringworm, typically appears as single or multiple, annular, scaly lesions with central clearing, a slightly elevated, reddened edge, and sharp margination on the trunk, extremities, or face. The border of the lesion may contain pustules or follicular papules. Itching is variable  Tinea Barbae Involves the skin and coarse hairs of the beard and mustache area. Occurs in adult men. Caused by zoophilic organism, therefore, farm workers are most often affected. Tinea barbae may cause scaling, follicular pustules, and erythema.  Tinea Faciei Occur in the non-bearded area of the face. May cause itching and burning, which become worse after sunlight exposure. Some round or annular red patches are present. Often, however, red areas may be indistinct, especially on darkly pigmented skin, and lesions may have little or no scaling or raised edges. Because of the subtle appearance, this dermatophytosis is sometimes known as “tinea incognito.”  Tinea Pedis Tinea pedis, or athlete's foot. It’s characterized by fissuring, maceration, and scaling in the interdigital spaces of the fourth and fifth toes. Cause itching or burning. It can cause a moccasin-like distribution pattern in which the plantar skin becomes chronically scaly and thickened, with hyperkeratosis and erythema of the soles, heels, and sides of the feet.  Tinea Manuum Infection of one or, occasionally, both hands. It often occurs in patients with tinea pedis. The palmar surface is diffusely dry and hyperkeratotic. When the fingernails are involved, vesicles and scant scaling may be present, and the condition resembles dyshidrotic eczema.  Tinea Cruris Is a dermatophyte infection of the groin. More common in men than in women and is frequently associated with tinea pedis. Tinea cruris occurs when ambient temperature and humidity are high. Affects the proximal medial thighs and may extend to the buttocks and abdomen. Causes burning and pruritus. Pustules and vesicles at the active edge of the infected area, along with maceration, are present on a background of red, scaling lesions with raised borders.  Tinea Unguium Infection of the nail, is a subset of onychomycosis, which also may be caused by yeast and non-dermatophyte molds. Risk factors for this infection include aging, diabetes, poorly fitting shoes, and the presence of tinea pedis. Thank you