What is the treatment for Aureobasidium pullulans infections?

Treatment of Aureobasidium pullulans Infections

The treatment of Aureobasidium pullulans infections requires amphotericin B (preferably liposomal formulation) as first-line therapy, often in combination with an echinocandin such as micafungin or caspofungin for severe or disseminated infections.

Identification and Clinical Presentation

Aureobasidium pullulans is a dematiaceous (dark-pigmented) yeast-like fungus that is ubiquitous in the environment. It can cause various clinical manifestations:

• Catheter-related fungemia and septic emboli
• Lymphatic system infections
• Skin and soft tissue infections
• Peritonitis (especially in patients with indwelling catheters)
• Keratitis (corneal infections)
• Systemic infections in immunocompromised hosts

Diagnostic Approach

• Blood cultures (may initially appear as oval yeast before transforming into a black mold on subculture) 1
• Tissue biopsy with fungal stains
• Molecular identification using ITS (Internal Transcribed Spacer) sequencing for definitive diagnosis 2
• Serum (1,3)-β-D-glucan levels can be used for diagnosis and monitoring treatment response 1

Treatment Recommendations

First-line Treatment

For invasive or disseminated infections:

• Liposomal amphotericin B (3-5 mg/kg/day IV) 3, 1
• Consider combination therapy with an echinocandin (micafungin 100-150 mg/day IV or caspofungin 70 mg loading dose followed by 50 mg/day IV) 1, 4

Alternative Therapies

• For triazole-susceptible isolates: voriconazole (6 mg/kg IV every 12h for 1 day, followed by 4 mg/kg IV every 12h; oral dosage is 200 mg every 12h) 3
• Posaconazole (400 mg BID PO after stabilization of disease) may be effective in some cases 4

Special Considerations

1. Catheter-related infections:

   • Removal of infected catheters is strongly recommended whenever possible 4
   • If catheter removal is not feasible, prolonged combination antifungal therapy is necessary 1

2. Ocular infections (keratitis):

   • Topical natamycin shows limited efficacy 5
   • Topical fluconazole or itraconazole has demonstrated better response 5
   • Severe cases may require systemic antifungal therapy with IV fluconazole 5
   • Therapeutic penetrating keratoplasty may be necessary in non-responsive cases 5

3. Duration of therapy:

   • For invasive infections: minimum 2-4 weeks after clinical resolution and negative cultures
   • For disseminated infections: extended therapy (months) may be necessary 1
   • Monitor serum (1,3)-β-D-glucan levels to assess response to therapy 1

Monitoring and Follow-up

• Regular assessment of clinical response within 48-72 hours of treatment initiation
• Monitor renal function when using amphotericin B formulations
• Serial serum (1,3)-β-D-glucan levels to track treatment response 1
• Follow-up blood cultures to confirm clearance of fungemia

Treatment Challenges

• A. pullulans may demonstrate resistance to triazole antifungals 1
• Nephrotoxicity with amphotericin B may require dosing adjustments (e.g., biweekly dosing during maintenance phase) 1
• Prolonged therapy is often necessary, especially in immunocompromised patients

Case-Specific Approaches

1. For catheter-related fungemia:

   • Combination of liposomal amphotericin B and micafungin or caspofungin 1, 4
   • Catheter removal whenever possible 4

2. For lymphatic system infections:

   • Amphotericin B deoxycholate has shown efficacy 6

3. For keratitis:

   • Topical fluconazole or itraconazole (after initial treatment with natamycin) 5
   • Consider systemic antifungal therapy in severe cases 5

While A. pullulans is a rare pathogen, it should be considered in immunocompromised patients with appropriate clinical presentations, especially those with indwelling catheters or other medical devices. Early identification and aggressive antifungal therapy are essential for successful treatment outcomes.