What is the treatment for a bacterial infection of the feet with athlete's foot (tinea pedis)?

Treatment of Bacterial Superinfection in Athlete's Foot

When athlete's foot becomes secondarily infected with bacteria (wet, macerated interdigital type), you must address BOTH the bacterial overgrowth and the underlying fungal infection simultaneously to prevent morbidity and restore quality of life.

Understanding the Pathophysiology

The key to effective treatment is recognizing that symptomatic, macerated athlete's foot represents a dermatophytosis complex where fungal invasion of the horny layer creates conditions for bacterial overgrowth 1. Moisture accumulation from sweating, tight shoes, or hot weather stimulates overgrowth of aerobic diphtheroids (causing common wet, macerated presentations) or gram-negative organisms like Pseudomonas and Proteus (causing more severe cases) 1.

Treatment Algorithm

Step 1: Immediate Bacterial Control (Critical First Priority)

• Suppress bacterial overgrowth through aggressive drying measures - this is the decisive element for symptomatic relief 1
• Apply aluminum chloride solution as the agent of choice, which combines broad-spectrum antimicrobial activity (including gram-negative coverage) with chemical drying properties 1
• Expose feet to air by wearing sandals to enhance water evaporation and prevent moisture accumulation that stimulates bacterial growth 1
• If aluminum chloride is unavailable, consider topical antibiotics with broad-spectrum coverage, though these lack the critical drying component 1

Step 2: Concurrent Antifungal Therapy

For interdigital tinea pedis with bacterial superinfection, use topical terbinafine 1% cream applied twice daily for 1 week - this is superior to longer courses of other agents 2, 3. The American Academy of Pediatrics specifically recommends this regimen for interdigital disease 2.

Alternative topical options if terbinafine is unavailable:

• Ciclopirox olamine 0.77% cream/gel twice daily for 4 weeks achieves 60% cure at end of treatment and 85% two weeks post-treatment 4, 2
• Clotrimazole 1% cream twice daily for 4 weeks, though less effective than terbinafine 4, 5

Step 3: Consider Oral Therapy for Severe Cases

Reserve oral antifungals for severe disease, failed topical therapy, concomitant nail involvement, or immunocompromised patients 2:

• Oral terbinafine 250 mg once daily for 1 week provides faster clinical resolution than 4 weeks of topical clotrimazole 4, 2
• Oral itraconazole 100 mg daily for 2 weeks has similar efficacy but slightly higher relapse rates 4, 2

Step 4: Essential Supportive Measures

• Wash affected skin with soap and water and dry completely between toes before applying any medication 3, 2
• Change socks daily and wear well-fitting, ventilated shoes 3, 2
• Clean athletic footwear periodically to prevent reinfection 2
• Apply foot powder after bathing (reduces recurrence from 8.5% to 2.1%) 2

Critical Pitfalls to Avoid

• Never treat only the fungus while ignoring bacterial overgrowth - the bacterial component causes the acute symptoms and morbidity 1
• Failing to achieve adequate drying is the most common cause of treatment failure in wet, macerated athlete's foot 1
• Neglecting contaminated footwear as a reinfection source leads to recurrence 2
• Not treating all infected family members simultaneously results in reinfection 2
• Cover active foot lesions with socks BEFORE wearing underwear to prevent spread to the groin 2

Special Considerations

• The dry, scaly type (dermatophytosis simplex) often alternates with the wet, macerated type (dermatophytosis complex), with flare-ups common in summer 1
• Risk factors include swimming, running, warm humid environments, male gender, obesity, and diabetes 4, 2
• No local treatment can permanently eradicate athlete's foot due to inevitable nail or sole reservoir infections that cause reinfection 1
• Terbinafine's fungicidal (not just fungistatic) action allows shorter treatment duration compared to azoles 5, 6
• Most concerning adverse events with oral terbinafine include occasional isolated neutropenia and rare liver failure in patients with pre-existing conditions 4

Treatment Endpoint

Mycological cure (not just clinical response) should be the definitive endpoint for adequate treatment 7. Consider follow-up with repeat mycology sampling at the end of the standard treatment period 7.