Content provided in partnership with

Health Care Industry

Treating Onychomycosis

American Family Physician, Feb 15, 2001 by Phillip Rodgers, Mary Bassler

Onychomycosis accounts for one third of fungal skin infections. Because only about one half of nail dystrophies are caused by fungus, the diagnosis should be confirmed by potassium hydroxide preparation, culture or histology before treatment is started. Newer, more effective antifungal agents have made treating onychomycosis easier. Terbinafine and itraconazole are the therapeutic agents of choice. Although the U.S. Food and Drug Administration has not labeled fluconazole for the treatment of onychomycosis, early efficacy data are promising. Continuous oral terbinafine therapy is most effective against dermatophytes, which are responsible for the majority of onychomycosis cases. Intermittent pulse dosing with itraconazole is as safe and effective as short-term continuous therapy but more economical and convenient. With careful monitoring, patients treated with the newer antifungal agents have a good chance of achieving relief from onychomycosis and its complications. (Am Fam Physician 2001;63:663-72,677-8.)

Most Popular Articles in Health: Fuel your workout: exercisers who eat before they work out have more energy ...; Soothe a dry, itchy scalp: 5 easy expert solutions; Cocktails and calories: Beer, wine and liquor calories can really add up. ...; The sour truth about apple cider vinegar - evaluation of therapeutic use; The, six best supplements you've never heard of: these secret weapons can ...; More »

Onychomycosis (tinea unguium) is a fungal infection of the nail bed, matrix or plate. Toenails are affected more often than fingernails.(1,2) Onychomycosis accounts for one third of integumentary fungal infections and one half of all nail disease.(1) Tinea unguium occurs primarily in adults, most commonly after 60 years of age. The incidence of this infection is probably much higher than the reported 2 to 14 percent.(1) Occlusive footwear, locker room exposure and the dissemination of different strains of fungus worldwide have contributed to the increased incidence of onychomycosis.(3)

Tinea unguium is more than a cosmetic problem, although persons with this infection are often embarrassed about their nail disfigurement. Because it can sometimes limit mobility, onychomycosis may indirectly decrease peripheral circulation, thereby worsening conditions such as venous stasis and diabetic foot ulcers.(4) Fungal infections of the nails can also be spread to other areas of the body and, perhaps, to other persons.

Dermatophytes, yeasts and nondermatophytic molds can infect the nails.1 The clinical significance of molds is uncertain, because they may be colonizing organisms that are not truly pathogenic.3,5

Classification of Onychomycosis

DISTAL SUBUNGUAL ONYCHOMYCOSIS

The most common form of tinea unguium is distal subungual onychomycosis, which can also be distal and lateral (Figures 1 and 2). Distal subungual onychomycosis may develop in the toenails, fingernails or both. Some degree of tinea pedis is almost always present. The infection is usually caused by Trichophyton rubrum, which invades the nail bed and the underside of the nail plate, beginning at the hyponychium and then migrating proximally through the underlying nail matrix(2,3) (Figure 3). Susceptibility to distal superficial onychomycosis may occur in an autosomal dominant pattern within families.(1)

WHITE SUPERFICIAL ONYCHOMYCOSIS

White superficial onychomycosis accounts for only 10 percent of onychomycosis cases.(3) The toenails are usually affected (Figure 4). White superficial onychomycosis is caused by certain fungi that directly invade the superficial layers of the nail plate and form well-delineated opaque "white islands" on the plate. As the disease progresses, these patches coalesce to involve the entire nail plate. The nail becomes rough, soft and crumbly. The most common causative agent is Trichophyton mentagrophytes.(1-3)

PROXIMAL SUBUNGUAL ONYCHOMYCOSIS

Proximal subungual onychomycosis is the least common form of tinea unguium in healthy persons (Figure 5). It occurs when the infecting organism, usually T. rubrum, invades the nail unit through the proximal nail fold, penetrates the newly formed nail plate and then migrates distally. Fingernails and toenails are equally affected.(1) This form of onychomycosis usually occurs in immunocompromised persons and is considered a clinical marker of human immunodeficiency virus infection.(1) Proximal subungual onychomycosis can also arise secondary to local trauma.(1-3)

CANDIDAL ONYCHOMYCOSIS

Patients with chronic mucocutaneous candidiasis may develop candidal infection of the nails. Candida species may invade nails previously damaged by infection or trauma.(1,3) Candidal paronychia more commonly affects the hands and usually occurs in persons who frequently immerse their hands in water.(5)

Total Dystrophic Onychomycosis

Total dystrophic onychomycosis may be the end result of any of the four main forms of onychomycosis. This condition is characterized by total destruction of the nail plate.(3)

Diagnosis

Because fungi are responsible for only about one half of nail dystrophies, the diagnosis of onychomycosis may need to be confirmed by potassium hydroxide (KOH) preparation, culture or histology. Psoriasis, lichen planus, contact dermatitis, trauma, nail bed tumor and yellow nail syndrome may be mistakenly diagnosed as onychomycosis.(1,2) A fungal etiology is unlikely if all fingernail or toenails are dystrophic.(3)

Health Care Industry

Treating Onychomycosis

American Family Physician, Feb 15, 2001 by Phillip Rodgers, Mary Bassler

Find Research Guides for:

Find Featured Titles for: Technology

Most Popular Articles in Health

Most Popular Publications in Health