Athlete's foot, or tinea pedis, can range from mild flaking of the skin to severe inflammation with blistering, itching, and pain. Recurrence is common.
Athlete’s foot is caused by invasion of the superficial layers of the skin by dermatophytes (molds) that require keratin for nutrition. These fungi must live on skin, hair or nails in order to survive.
All human dermatophyte infections are caused by species from three genera of fungi: Trichophyton, Epidermophyton, and Microsporum. These fungi differ from infections caused by Candida species in that they rarely, if ever, become invasive—that is, they only cause localized infection. (The Merck Manual, 18th Edition. Dermatophytoses. 2006. Pp 988-93)
How Do People Get Athlete’s Foot?
- Athlete’s foot typically spreads from person to person. Usually, an infected individual deposits the fungus on environmental surfaces—showers, tubs, socks, shoes, etc.—and another person acquires the infection by walking in the same area or by sharing contaminated footwear.
- Infection can also be transferred from one person’s feet to another through direct contact (i.e., by touching bare feet).
- Most people who are exposed to the molds that cause athlete’s foot don’t develop signs or symptoms; those who do may have deficiencies in their immune systems (inherited or acquired) that allow the infection to take hold.
What Does Athlete’s Foot Look Like?
Athlete’s foot has three common presentations:
- Interdigital form: This is the most common presentation. It is characterized by fissuring, scaling, and maceration (softening and shriveling) in the spaces between the toes—usually the third, fourth and fifth toes. Affected persons often complain of burning and itching.
- Chronic hyperkeratotic form: This form manifests as a persistent, moccasin-like distribution of thickened skin, redness, and flaking along the soles, heels and sides of the feet. Itching and burning are prominent symptoms; cracking and bleeding may also occur.
- Vesiculobullous form: This form, which can be acutely painful, is characterized by the development of vesicles (small, fluid filled bumps), pustules, and bullae (large, fluid-filled blisters). Inflammation—usually more prominent on the soles of the feet—is common. This form may mimic other conditions, such as contact dermatitis (e.g., poison ivy) or pustular psoriasis.
Secondary infection by Streptococcus is a potential complication of all three forms of athlete’s foot. The bacterium is able to colonize the web spaces between the toes after the fungi have broken down some of the skin’s normal immune defenses.
How is Athlete’s Foot Treated?
- Athlete’s foot usually responds to topical applications of antifungal creams to the web spaces between the toes and other affected areas. Some studies show that cure rates are higher and treatment is of shorter duration with fungicidal medications (e.g., Naftin, Lamisil) than with fungistatic agents (e.g., Lotrimin, Nizoral, Micatin). (Evans E, et al. Comparison of terbinafine and clotrimazole in treating tinea pedis. BMJ 1993;307:645-7 and Evans E. Tinea pedis: clinical experience and efficacy of short treatment. Dermatology 1997;194[suppl 1]:3-6).
- Many people respond adequately to topical applications of tea tree oil, goldenseal, undecylenic acid (a castor oil byproduct that is also sometimes used to treat nail fungus), or other herbal products.
- Occasionally, oral therapy with antifungal agents is required: refractory cases, severe infections, or cases with coexisting toenail infection may merit systemic treatment. Furthermore, when bacterial co-infection is suspected—in cases of vesiculobullous tinea pedis, for example—antifungal medications may be combined with antibiotic therapy.
Prevention of Athlete’s Foot
- Reinfection or recurrence of athlete’s foot is common, particularly if the toenails are involved. Therefore, nail infections should also be addressed to reduce the chances of recurrent or refractory infection.
- Footwear should be disinfected each day—by spraying with Lysol spray, dusting with antifungal powders, etc.—and feet should be kept dry. For individuals whose feet sweat excessively, this may entail multiple daily changes of socks (cotton is recommended).
- Shoes should allow free movement of air; occlusive leather or plastic footwear traps moisture and increases the ambient temperature around the feet.
- Patients who have athlete’s foot—and those who have been previously infected—should wear sandals in shower areas, particularly in public places such as locker rooms and swimming facilities.
(From Hainer B. Dermatophyte infections. Am Fam Phys. 2003;67(1):101-8)
The copyright of the article Athlete's Foot in Skin Disease is owned by Stephen Allen Christensen. Permission to republish Athlete's Foot in print or online must be granted by the author in writing.
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