Successful Treatment of Paecilomyces variotii Pneumonia and Lupus Nephritis With Posaconazole-Cyclophosphamide Co-administration Without Drug Interaction–Induced Toxicity

Paecilomyces variotii is an opportunistic mold that causes pulmonary infections in immunosuppressed humans that are often treated with triazole therapy. Lupus nephritis is a major cause of progressive kidney disease in patients with systemic lupus erythematosus, often requiring cyclophosphamide-based therapies. Triazole-cyclophosphamide co-administration is challenging as triazoles increase cyclophosphamide concentrations, which can worsen cyclophosphamide toxicity. We describe herein a patient with Paecilomyces variotii pneumonia and concomitant lupus nephritis who was successfully treated with posaconazole and echinocandin-bridged interruptions to allow for cyclophosphamide therapy. This regimen was well-tolerated without cyclophosphamide toxicity and achieved improvements in both fungal pneumonia and renal function.