POTD: Tinea Pedis (Athlete's Foot)

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This PODT is inspired by a recent case I had in while working in Peds and is something we may encounter often in the summer. This is a perfect example of a fast track compliant that we may have not seen a lot of during COVID.

The patient was a young male in his 20s who works in construction and wears heavy boots and socks for about 8 hours of the day in the heat. He presented with 1 days of sloughing of the skin of both of his feet with discharge.

 Lets discuss Tinea Pedis (Athlete’s Foot):

 Tines pedis is a dermatophyte infection of the skin on the foot.

 Etiology and Risk Factors:

  • Usually occurs in adults and adolescents and is rare prior to puberty

  • Infection is acquired by means of direct contact with the causative organism

  • Commonly seen in patients who have a history of walking barefoot in locker rooms or swimming pool facilities

  • Also commonly seen in patients who wear occlusive footwear

Predisposing factors to consider

  • Diabetes Mellitus

  • Immunodeficiency, Systemic corticosteroid use, or use of immune suppressive agents

  • Poor peripheral circulation or lymphoedema

  • Excessive sweating (hyperhidrosis)

 Who would have know that there are different types of tinea pedis?

  •  Types of Tinea Pedis:

    • Interdigital tinea pedis: Manifests as pruritic erosions or scales between the toes, most commonly in the third and fourth digital interspaces

      • More severe form of this is known as Ulcerative tinea pedis. This is generally associated with secondary bacterial infection

    • Hyperkeratotic (Moccasin-Type): Characterized by diffuse hyperkeratotic eruption involving the soles and medial and lateral surfaces of the feet.    

    • Vesiculobullous (inflammatory-type): Pruritic, sometimes painful, vesicular or bullous eruption. Medial foot often affected 

Management:

  • Topical antifungal therapy is treatment of choice for most patients.

    1. Example of topical antifungal: Azoles, Allylamines, Butenafine, Ciclopirox, Tolnaftate, and Amorolfine. Recommended to apply once or twice a day for four weeks. (Refer to references for dosages and frequency)

    2. Beneficial and more effective for patients to use the suspension formulation of these medications

  • Systemic antifungal agents are primarily reserved for patients who fail topical therapy

    1.   Terbinafine 250mg per day for 2 weeks in adults

      1. Most check LFTs prior to administration and patients need to follow up and have LFTs checked while receiving treatment

      2. Peds dosing:

        • 10 to 20kg: 62.5mg/day

        • 20 to 40kg: 125mg/day

        • Above 40kg: standard adult dosing

    • Itraconazole 200mg per day for two weeks

      •   Peds dosing:

        • 3 to 5 mg/kg per day

    • Fluconazole 150mg once weekly for two to six weeks

      • Peds dosing:

        •   6mg/kg once weekly

  • ·Ulcerative Tinea Pedis;

    •   Always treatment with systemic antifungal agents in addition to topical antifungals

    • Make sure to add in addition to your antifungal an antibiotic such as Keflex

    • Outpatient podiatry follow up should be given to patients

  • Prevention

    • Use of sock with wick-away material

    • Use of desiccating foot powders

    • Tx of hyperhidrosis if there is history of moist feet

    •   Tx of shoes with antifungal powder

    •   Avoidance of occlusive foot wear

 We diagnosed our patient with ulcerative tinea pedis. We started the patient on Terbinafine, Ciclopriox, and Keflex and arranged for podiatry follow up. Our patients case was unique in the fact that the patient had bilateral involvement normally this occurs unilateral.

 References :

·      https://www.uptodate.com/contents/dermatophyte-tinea-infections?search=tinea%20pedis&source=search_result&selectedTitle=1~103&usage_type=default&display_rank=1#H2658711829

·      https://www.uptodate.com/contents/image?csi=18b425c8-5b1f-4694-a039-5bc8aa27c160&source=contentShare&imageKey=PC%2F76148

·      https://wikem.org/wiki/Tinea_pedis

·      https://www.aafp.org/afp/2014/1115/p702.html

·      https://accessemergencymedicine.mhmedical.com/content.aspx?sectionid=109447903&bookid=1658

·      https://dermnetnz.org/topics/tinea-pedis/

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