Fungal infections of the skin and nails

Organisms called dermatophytes cause the majority of superficial fungal infections of the skin, hair and nails. The most common dermatophytes that infect humans belong to 

Superficial fungal infections can usually be treated with topical preparations, but systemic antifungal drugs can be necessary for nail and scalp infections, or if skin infection is extensive and unresponsive to topical therapy. 

---

The fungal infections of the skin and nails include Tinea pedis (athlete s foot), T. capitis and T. 

Indications Fungal infections of the skin and nails Category Antimycobacterial Half-life 22-26 hours... 

For example, griseofulvin has an affinity for keratin. Since this drug can be used to treat fungal infections of the skin and nails its sequestration into keratin is something of an advantage. 

Drugs used to treat fungal infection of the skin and nails... 

Tolnaftate, a much older drug, is chemically a thiocarbamate but has the same mechanism of action as the allyl amines. These drugs have a more limited spectrum of activity than the azoles and are effective only against dermatophytes. Therefore, they are employed in the treatment of fungal infections of the skin and nails (35). 

Gupta AK, Cooper EA, Ryder JE, et al. Optimal management of fungal infections of the skin, hair, and nails. Am J Clin Dermatol 2004 5 225-237. 

Suhonen, R. E., Dawber, R. P. R., and Ellis, D. H. (1999). Fungal Infections of the Skin, Hair and Nails. London Martin Dunitz. 

Terbinafine interferes with ergosterol biosynthesis, and thereby with the formation of the fungal cell membrane. It is absorbed from the gastrointestinal tract and undergoes extensive metabolism in the liver (tj 14 h). Terbinafine is used topically for dermatophyte infections of the skin and orally for infections of hair and nails where the site (e.g. hair), severity or extent of the infection render topical use inappropriate (see p. 315). Treatment (250 mg/d) may need to continue for several weeks. It may cause nausea, diarrhoea, dyspepsia, abdominal pain, headaches and cutaneous reactions. 

Tinea infections are superficial fungal infections in which the pathogen remains within the keratinous layers of the skin or nails. Typically these infections are named for the affected body part, such as tinea pedis (feet), tinea cruris (groin), and tinea corporis (body). Tinea infections are commonly referred to as ringworm due to the characteristic circular lesions. In actuality, tinea lesions can vary from rings to scales and single or multiple lesions. 

Dermatophyte is the term applied to a range of fungi capable of colonizing the skin, nails or hair. The principal dermatophytic fungi are Trichophyton, Microsporum and Epidermophyton species. The most commonly encountered dermatophytic infections are athlete s foot (infection of the foot) and ringworm (fungal infection of the scalp or skin). 

The most widespread are dermatophytic fungal infections, which include skin, hair, and nails. Most infections can be cured by using topical drugs, such as tolnaftate, undecylenic acid, haloprogin, clotrimazole, and miconazole. Griseofulvin is used orally for deep infections, in particular for infections of the nail bed. Currently, ketoconazole is widely used for treating chronic dermatophytes. 

Over the last fifty years, as chemotherapeutics for the treatment of cancer, bacterial infections, and to prevent transplant rejections have improved, there has been a concomitant increase in the number of patients suffering from fungal infections. In the past, most fungal infections were superficial, affecting only the skin, hair, or nails. However, as medical science has progressed in other disease areas, many more patients are immunocompromised, which has resulted in a greater incidence of systemic fungal infections. 

Athlete s foot is the commonest of a group of topical fungal infections (see Chapter 28) caused by dermatophytes, organisms that invade and proliferate on the outermost horny layer (stratum corneum) of the skin, hair and nails. They do not normally penetrate deeper into the skin or tissues. Dermatophytes tend to thrive in areas of the body that are occluded and moist. 

---