What is the treatment for Trichophyton rubrum infections?

Treatment of Trichophyton rubrum Infections

For T. rubrum infections, oral terbinafine 250 mg once daily is the most effective treatment, with topical ciclopirox olamine 0.77% cream/gel as the superior topical alternative when oral therapy is not indicated.

Treatment Selection by Site of Infection

Tinea Corporis (Body)

• Oral terbinafine 250 mg once daily for 1-2 weeks is superior for T. rubrum infections, offering convenient once-daily dosing and excellent efficacy 1, 2
• For patients over 40 kg, the recommended dose is 250 mg once daily for 2-4 weeks 1
• Oral itraconazole 100 mg once daily for 15 days achieves 87% mycological cure rates, significantly superior to griseofulvin's 57% cure rate 3, 1, 2
• Topical therapy with ciclopirox olamine 0.77% cream/gel applied twice daily for 4 weeks achieves approximately 60% cure at end of treatment and 85% cure two weeks after treatment completion, superior to clotrimazole 1, 2

Tinea Pedis (Athlete's Foot)

• Ciclopirox olamine 0.77% cream or gel applied twice daily for 4 weeks is the first-line topical treatment, with proven efficacy against T. rubrum and T. mentagrophytes 3, 4, 2
• Topical terbinafine 1% cream applied twice daily for 1 week achieves 66% effective cure rate 2
• For severe disease or failed topical therapy, oral terbinafine 250 mg once daily for 1 week provides faster clinical resolution than topical treatments 2
• Oral itraconazole 100 mg daily for 2 weeks has similar efficacy to terbinafine but slightly higher relapse rate 2

Onychomycosis (Nail Infections)

• Oral terbinafine 250 mg daily is the most effective treatment for T. rubrum nail infections 5, 6
• Standard treatment for toenail infections is 12 weeks of daily therapy, achieving 70% mycological cure and 59% effective treatment rates 5
• For fingernail onychomycosis, 250 mg daily for 6 months achieves clinical and mycological cure in all treated patients 7
• Intermittent pulse-dosed terbinafine (250 mg/day for 7 consecutive days every 3 months) is effective for distal subungual onychomycosis, with 93% cure rates, but treatment every 4 months shows significantly more failures 8

Treatment Endpoints and Monitoring

The endpoint of treatment must be mycological cure (negative microscopy and culture), not just clinical improvement, as clinical appearance may improve while infection persists 1

• If clinical improvement occurs but mycology remains positive, continue therapy for an additional 2-4 weeks 1
• Follow-up with repeat mycology sampling at the end of the standard treatment period is recommended 2
• Monitor for rare but serious adverse events with oral terbinafine, including neutropenia and liver failure, particularly in patients with preexisting conditions 2

Contraindications and Safety

Oral terbinafine is contraindicated in patients with:

• Active or chronic liver disease 1
• Lupus erythematosus 1
• Porphyria 1
• Known hypersensitivity to oral terbinafine 1

Drug Interactions

• Terbinafine interacts with multiple medications, including cyclosporine, fluconazole, and caffeine, requiring monitoring or adjustment when co-administered 1
• Terbinafine is extensively metabolized by at least seven CYP isoenzymes with major contributions from CYP2C9, CYP1A2, CYP3A4, CYP2C8, and CYP2C19 5

Prevention of Recurrence and Transmission

• Avoid skin-to-skin contact with infected individuals and cover active lesions 3, 1, 2
• Do not share towels, clothing, or other personal items (fomites) 3, 1, 2
• Thoroughly dry between toes after showering and change socks daily 4, 2
• Clean athletic footwear periodically and apply foot powder after bathing 4, 2
• Cover active foot lesions with socks before wearing underwear to prevent spread to the groin area 2
• Limit exposure to swimming pools associated with outbreaks 3, 1

Risk Factors to Address

• Swimming, running, and warm humid environments increase risk of T. rubrum pedis infections 3, 2
• Male gender, obesity, and diabetes are additional risk factors for tinea pedis 3, 4, 2
• Underlying conditions such as hay fever/asthma, atopic eczema, collagen disease, or ichthyosis may contribute to treatment failure 9

Common Pitfalls

• Failing to treat all infected family members simultaneously can result in reinfection 2
• Neglecting to address contaminated footwear can lead to recurrence 2
• Stopping treatment based on clinical improvement alone without confirming mycological cure leads to relapse 1
• In vitro resistance to antifungal agents is rare; treatment failures are more commonly due to underlying immunological abnormalities or inadequate treatment duration 10, 9