What is the treatment for onychomycosis caused by Cladosporium and Pithomyces?

Treatment of Onychomycosis Caused by Cladosporium and Pithomyces

For onychomycosis caused by non-dermatophyte molds like Cladosporium and Pithomyces, oral itraconazole is the first-line treatment, administered as 400 mg daily for 1 week per month (pulse therapy) for 2-3 months for fingernails and 3-4 months for toenails. 1

Diagnostic Confirmation

Before initiating treatment:

• Obtain mycological confirmation through microscopy and culture
• Ensure proper identification of the causative organism
• Interpret cultures of non-dermatophyte molds carefully, as they may be saprophytic in previously damaged nails 1

Treatment Algorithm

First-Line Treatment:

• Oral Itraconazole:
  • Dosage: 400 mg daily for 1 week per month (pulse therapy)
  • Duration: 2 months for fingernail infection, 3-4 months for toenail infection 1
  • Take with food for optimal absorption in an acidic environment 1
  • Monitor hepatic function tests in patients with pre-existing liver issues or those receiving continuous therapy for more than a month 1

Alternative Options:

• Terbinafine: While highly effective for dermatophytes, it has limited efficacy against non-dermatophyte molds like Cladosporium and Pithomyces
• Fluconazole: May be considered if itraconazole is not tolerated, at 150-450 mg weekly for 3-6+ months 1

Adjunctive Measures:

• Nail Debridement: Consider partial nail removal if treatment fails due to subungual dermatophytoma (dense fungal mass preventing drug penetration) 1
• Topical Therapy: Can be used as adjunctive treatment but is generally insufficient as monotherapy for non-dermatophyte mold infections 1

Prevention of Recurrence

Recurrence is common with onychomycosis. Implement these preventive measures:

• Discard old, contaminated footwear or sanitize using naphthalene mothballs in a sealed plastic bag for 3+ days 1, 2
• Apply antifungal powders (miconazole, clotrimazole, tolnaftate) inside shoes 1, 2
• Wear protective footwear in public bathing facilities, gyms, and hotel rooms 1, 2
• Keep nails short and avoid sharing nail clippers 1
• Wear cotton, absorbent socks 1
• Treat all infected family members simultaneously to prevent reinfection cycles 1, 2

Treatment Challenges and Considerations

• Non-dermatophyte molds like Cladosporium and Pithomyces are generally more resistant to standard antifungal therapy than dermatophytes
• Complete cure may take 6-12 months due to slow nail growth 2
• Set appropriate expectations regarding treatment duration and potential for recurrence
• Monitor for common adverse effects:
  • Itraconazole: Headache and gastrointestinal upset 1
  • Terbinafine: Headache, taste disturbance, and gastrointestinal upset 1
  • Fluconazole: Headache and gastrointestinal upset 1

Treatment Failure Management

If initial treatment fails:

1. Verify diagnosis with repeat mycological testing
2. Consider partial nail removal to eliminate subungual dermatophytoma 1
3. Try an alternative systemic antifungal agent
4. Consider combination therapy with both oral and topical antifungals

Remember that onychomycosis should not be considered a trivial disease, as it can impact quality of life and potentially lead to complications, especially in elderly or diabetic patients 2.