What treatment options are available for a patient with extensive athlete's foot that has not responded to topical treatment and oral terbinafine (Lamisil)?

Treatment of Refractory Extensive Athlete's Foot

For extensive athlete's foot that has failed both topical therapy and oral terbinafine, switch to oral itraconazole as the next-line systemic antifungal agent.

Immediate Next Steps

Verify Treatment Failure and Obtain Cultures

• Before switching therapy, obtain fungal cultures and consider discontinuing antifungals for a few days to optimize specimen collection 1
• Confirm the diagnosis is truly dermatophyte infection rather than bacterial superinfection or a mimicking condition 2
• Assess for secondary bacterial overgrowth (particularly gram-negative organisms like Pseudomonas or aerobic diphtheroids), which commonly complicates extensive tinea pedis and requires concurrent treatment 3

Second-Line Oral Antifungal Therapy

Oral itraconazole is the recommended alternative when terbinafine fails:

• Use pulse dosing: 200-400 mg per day for 1 week per month 1
• For extensive tinea pedis, consider continuous dosing for 2 weeks at 100 mg daily 4
• Itraconazole has similar mycological efficacy to terbinafine but may have slightly higher relapse rates 1
• Take with food and acidic pH for optimal absorption 4

Alternative option - Oral fluconazole (less effective but useful if itraconazole contraindicated):

• Fluconazole is less effective than both terbinafine and itraconazole for dermatophyte infections 1
• Dosing: 150 mg once weekly as pulse therapy 1
• Has fewer drug interactions due to weaker cytochrome P450 inhibition 1

Critical Adjunctive Measures

Address Bacterial Superinfection

• Bacterial overgrowth is essential to suppress in symptomatic athlete's foot 3
• The wet, macerated presentation indicates bacterial involvement (aerobic diphtheroids or gram-negative organisms) 3
• Consider topical antibacterial agents or aluminum chloride solution for its dual antimicrobial and drying properties 3

Optimize Environmental Factors

• Drying is the decisive element in treatment success 3
• Expose feet to air (wear sandals) to enhance water evaporation 3
• Apply foot powder after bathing (reduces recurrence from 8.5% to 2.1%) 1
• Change socks daily and clean athletic footwear periodically 1

Prevent Reinfection Sources

• Examine and treat concomitant onychomycosis, as nail infection serves as a reservoir for reinfection 1, 2
• Check for dermatophyte infection at other body sites (groin, body folds, hands) - present in 25% of cases 1
• Treat all infected family members simultaneously to prevent reinfection 1
• Address contaminated footwear as a source of recurrence 1

Monitoring and Follow-Up

• Monitor liver function tests at baseline and during prolonged therapy, especially with itraconazole 4
• Follow up carefully to ensure treatment effectiveness 4
• Consider culture at end of treatment to confirm mycological clearance 4

Common Pitfalls to Avoid

• Do not assume treatment failure is due to drug resistance alone - poor compliance, inadequate drug penetration, bacterial superinfection, or reinfection from nails/footwear are more common causes 4
• Do not neglect to dry between toes thoroughly - moisture accumulation stimulates bacterial overgrowth that perpetuates symptoms 3
• Do not treat the feet in isolation - failure to address nail involvement or other body sites leads to recurrence 1, 2