This patient has tinea pedis, which is characterized by superficial scaling in a “moccasin” distribution on the feet, maceration in the toe webs spaces, and often dystrophic toenails corresponding to onychomycosis. The recommended treatment is a topical antifungal agent such as clotrimazole. Other azole-based agents or topical terbinafine (squalene epoxidase inhibitors) may also be used. Over-the-counter and prescription preparations are equally effective in treating tinea pedis. A 2- to 4-week course in conjunction with washing footwear to help remove any fomites also is necessary. Other associated management may include use of foot powder as a drying agent to prevent maceration, avoidance of occlusive footwear, and treating shoes with antifungal powders before being worn.
Topical betamethasone is a topical glucocorticoid that is beneficial in treated eczematous dermatitis. Although it may initially help with the inflammation of tinea pedis, it may result in a florid infection and potentially a pustular eruption known as Majocchi granuloma.
Although FDA approved, clotrimazole-betamethasone combination cream also is not the preferred treatment for dermatophyte infections as it can lead to increased side effects because of the potent topical glucocorticoid. Although this combination of a glucocorticoid and an antifungal agent is commonly prescribed, the combined agents can partially suppress a superficial dermatophyte infection but may ultimately make the infection more severe and deeper, requiring systemic antifungal agents to treat the disease. The use of this combination cream should be avoided because it can lead to treatment failures and skin atrophy related to prolonged topical glucocorticoid use, and has an increased cost compared with topical antifungal agents alone. It can be effective in treating chronic paronychia.
Although topical nystatin is an antifungal medication, it is effective only against Candida spp. and is ineffective against other dermatophytes. Tinea pedis is secondary to dermatophytes, not Candida, so nystatin should not be used in this patient.
