Laboratory Studies
- In suspected tinea pedis, order direct potassium hydroxide (KOH) staining for fungal elements. Usually, the fungal elements are easily identified from scaly lesions. Using counterstains may enhance the visibility of the hyaline hyphae found in dermatophyte infections. Examples include the chitin-specific stains chlorazol black E, which stains hyphae blue-black, and calcofluor, which fluoresces hyphae under a fluorescent microscope.
- A sample from skin scrapings may be obtained using a No. 15 blade.
- When blisters are present, the highest fungal yield is obtained by scraping the roof of the vesicle.
- A fungal culture may be performed to confirm the diagnosis of tinea pedis and to identify the pathogenic species.
- Common media include dermatophyte test medium, Mycosel, or mycobiotic agar.
- Use caution when choosing the correct culture medium because certain media (eg, dermatophyte test medium) contain cycloheximide, which inhibits the growth of nondermatophyte molds. Because these fungi can be a factor in tinea pedis, use agar without cycloheximide.
Histologic Findings
A skin biopsy and histopathological study are rarely needed to confirm a diagnosis of tinea pedis. Fungal elements within the stratum corneum can usually be identified using periodic acid-Schiff or Gomori methenamine-silver stain but may be sparse or absent in inflammatory or interdigital tinea pedis complicated by secondary bacterial infection. Neutrophils may be noted within the stratum corneum, a finding that should prompt consideration of a dermatophyte infection. In vesicular tinea pedis, spongiotic intraepidermal vesicles are present; in the chronic hyperkeratotic (moccasin) type, hyperkeratosis and epidermal acanthosis usually are present. Both types are associated with an acute or chronic dermatitis that may contain eosinophils.
Pellizzari C. Recherche sur Trichophyton tonsurans. G Ital Mal Veneree. 1888;29:8.
Lopez-Martinez R, Manzano-Gayosso P, Hernandez-Hernandez F, Bazan-Mora E, Mendez-Tovar LJ. Dynamics of dermatophytosis frequency in Mexico: an analysis of 2084 cases. Med Mycol. Nov 3 2009;[Medline].
Zhan P, Ge YP, Lu XL, She XD, Li ZH, Liu WD. A case-control analysis and laboratory study of the two feet-one hand syndrome in two dermatology hospitals in China. Clin Exp Dermatol. Oct 23 2009;[Medline].
Leyden JJ. Progression of interdigital infections from simplex to complex. J Am Acad Dermatol. May 1993;28(5 Pt 1):S7-S11. [Medline].
Gentles JC. The isolation of dermatophytes from the floors of communal bathing places. J Clin Pathol. Nov 1956;9(4):374-7. [Medline].
Gentles JC, Evans EG. Foot infections in swimming baths. Br Med J. Aug 4 1973;3(5874):260-2. [Medline].
Parish LC, Parish JL, Routh HB, Fleischer AB Jr, Avakian EV, Plaum S, et al. A randomized, double-blind, vehicle-controlled efficacy and safety study of naftifine 2% cream in the treatment of tinea pedis. J Drugs Dermatol. Nov 1 2011;10(11):1282-8. [Medline].
Weinberg JM, Koestenblatt EK. Treatment of interdigital tinea pedis: once-daily therapy with sertaconazole nitrate. J Drugs Dermatol. Oct 1 2011;10(10):1135-40. [Medline].
Carrillo-Muñoz AJ, Tur-Tur C, Cárdenes DC, Estivill D, Giusiano G. Sertaconazole nitrate shows fungicidal and fungistatic activities against Trichophyton rubrum, Trichophyton mentagrophytes, and Epidermophyton floccosum, causative agents of tinea pedis. Antimicrob Agents Chemother. Sep 2011;55(9):4420-1. [Medline]. [Full Text].
Gupta AK, Baran R, Summerbell R. Onychomycosis: strategies to improve efficacy and reduce recurrence. J Eur Acad Dermatol Venereol. Nov 2002;16(6):579-86. [Medline].
Matricciani L, Talbot K, Jones S. Safety and efficacy of tinea pedis and onychomycosis treatment in people with diabetes: a systematic review. J Foot Ankle Res. Dec 4 2011;4:26. [Medline]. [Full Text].
Savin R, De Villez RL, Elewski B, et al. One-week therapy with twice-daily butenafine 1% cream versus vehicle in the treatment of tinea pedis: a multicenter, double-blind trial. J Am Acad Dermatol. Feb 1997;36(2 Pt 1):S15-9. [Medline].
Gul U, Cakmak SK, Ozel S, Bingol P, Kaya K. Skin disorders in patients with hemiplegia and papaplegia. J Rehabil Med. Jul 2009;41(8):681-3. [Medline].
Bristow IR, Spruce MC. Fungal foot infection, cellulitis and diabetes: a review. Diabet Med. May 2009;26(5):548-51. [Medline].
[Guideline] Wound, Ostomy, and Continence Nurses Society (WOCN). Guideline for management of wounds in patients with lower-extremity venous disease. National Guideline Clearinghouse. 2005.
[Guideline] Frykberg RG, Zgonis T, Armstrong DG, et al. American College of Foot and Ankle Surgeons. Diabetic foot disorders: a clinical practice guideline. J Foot Ankle Surg. Sep-Oct 2006;45(5):S2-66.
Bolognia JL, Jorizzo JL, Rapini RP, et al. Dermatology. New York, NY: Mosby; 2003:1174-85.
Brodell RT, Elewski B. Antifungal drug interactions. Avoidance requires more than memorization. Postgrad Med. Jan 2000;107(1):41-3. [Medline].
Brodell RT, Elewski BE. Clinical pearl: systemic antifungal drugs and drug interactions. J Am Acad Dermatol. Aug 1995;33(2 Pt 1):259-60. [Medline].
[Guideline] Drake LA, Dinehart SM, Farmer ER, et al. Guidelines of care for superficial mycotic infections of the skin: tinea corporis, tinea cruris, tinea faciei, tinea manuum, and tinea pedis. Guidelines/Outcomes Committee. American Academy of Dermatology. J Am Acad Dermatol. Feb 1996;34(2 Pt 1):282-6. [Medline].
Elewski B, Hay RJ. International summit on cutaneous antifungal therapy. Boston, Massachusetts, Nov. 11-13, 1994. J Am Acad Dermatol. Nov 1995;33(5 Pt 1):816-22. [Medline].
Elewski BE. Tinea pedis and tinea manuum. In: Demis DJ. Clinical Dermatology. Vol 3. Philadelphia, Pa: Lippincott; 1999:Unit 17-9; 1-11.
Elewski BE. Cutaneous mycoses in children. Br J Dermatol. Jun 1996;134 Suppl 46:7-11: discussion 37-8. [Medline].
Elewski BE. Mechanisms of action of systemic antifungal agents. J Am Acad Dermatol. May 1993;28(5 Pt 1):S28-S34. [Medline].
Elewski BE. Trichophyton rubrum: Dermatophytoses in evolution. Adv Dermatol. 1994;9:110-11.
Elewski BE, Haley HR, Robbins CM. The use of 40% urea cream in the treatment of moccasin tinea pedis. Cutis. May 2004;73(5):355-7. [Medline].
Elewski BE, Malden MA. Cutaneous Fungal Infections. 2nd ed. London: Blackwell Science; 1998:13-72, 321-46.
Freedberg IM, Eisen AZ, Wolff K, et al. Fitzpatrick's Dermatology in General Medicine. 5th ed. New York, NY: McGraw-Hill; 1999:2349-51.
Leyden JJ, Kligman AM. Interdigital athlete's foot. The interaction of dermatophytes and resident bacteria. Arch Dermatol. Oct 1978;114(10):1466-72. [Medline].
Malcolm B. Tinea pedis. Practitioner. Mar 1998;242(1584):225. [Medline].
Medical Economics Staff. Physicians' Desk Reference. 53rd ed. Montvale, NJ: Thomson Healthcare; 1999.
Mitchell JH. Ringworm of hands and feet. J Am Med Assoc. Jun 9 1951;146(6):541-6. [Medline].
Noble SL, Forbes RC, Stamm PL. Diagnosis and management of common tinea infections. Am Fam Physician. Jul 1998;58(1):163-74, 177-8. [Medline].
Resnik SS, Lewis LA, Cohen BH. The athlete's foot. Cutis. Sep 1977;20(3):351-3, 355. [Medline].
Rippon JW. Medical Mycology: The Pathogenic Fungi and the Pathogenic Actinomycetes. 3rd ed. Philadelphia, Pa: WB Saunders; 1988:169-275.
Watanabe K, Taniguchi H, Katoh T. Adhesion of dermatophytes to healthy feet and its simple treatment. Mycoses. 2000;43(1-2):45-50. [Medline].
Weidman FD. Laboratory aspects of epidermophytosis. Arch Dermatol. 1927;15:415-50.

