Vancomycin Has No Role in Treating Blastomycosis
Vancomycin is not effective for treating blastomycosis and should never be used for this fungal infection. Vancomycin is an antibacterial agent with activity exclusively against gram-positive bacteria and has no antifungal properties 1.
Why Vancomycin is Inappropriate
- Vancomycin's mechanism of action involves inhibition of bacterial cell-wall biosynthesis and has no activity against fungi 1
- The FDA-approved indications for vancomycin are limited to bacterial infections caused by gram-positive organisms such as Staphylococcus, Streptococcus, and Enterococcus species 1
- Blastomycosis is caused by the thermally dimorphic fungus Blastomyces dermatitidis, which requires antifungal therapy, not antibacterial agents 2, 3, 4
Correct Treatment Options for Blastomycosis
Life-Threatening or CNS Disease
- Amphotericin B (lipid formulation preferred) at 3-5 mg/kg/day is the mandatory first-line treatment for severe/life-threatening blastomycosis, CNS involvement, immunocompromised patients, and pregnant women 5
- For CNS blastomycosis specifically, use lipid amphotericin B 5 mg/kg/day for 4-6 weeks, followed by step-down azole therapy for at least 1 year 5
- Mortality rates of 30-40% occur in immunocompromised patients, with most deaths in the first few weeks, making early aggressive amphotericin B treatment critical 2, 5
Mild to Moderate Disease
- Itraconazole 200-400 mg/day for 6-12 months is the preferred treatment for non-life-threatening, non-CNS blastomycosis in immunocompetent patients 2
- Alternative azoles include ketoconazole 400-800 mg/day or fluconazole 400-800 mg/day, though itraconazole is more efficacious 2
Step-Down Therapy Strategy
- After 1-2 weeks of amphotericin B for severe disease, switch to itraconazole 200 mg twice daily to complete 6-12 months total therapy for pulmonary disease and ≥12 months for disseminated disease 5
- Monitor serum itraconazole levels after 2 weeks with target >1.0 μg/mL 5
Critical Pitfall to Avoid
Using antibacterial agents like vancomycin for fungal infections will result in treatment failure and disease progression. Always confirm the diagnosis of blastomycosis through culture, histopathology showing characteristic broad-based budding yeast, or antigen detection before initiating appropriate antifungal therapy 2, 4.