Bloodstream infection by Fusarium Solani Complex in a paediatric patient affected by acute lymphoblastic leukaemia and P450 cytochrome polymorphism: A case report

Background and Purpose: Fusarium species are causative agents of a wide range of opportunistic infections, ranging from superficial to disseminated forms, particularly in nosocomial settings. Children with haematological malignancies may develop severe fungal infections, such as fusariosis, that have proven notoriously challenging to diagnose and treat, with high mortality rates. Case Presentation: This report aimed to describe an invasive Fusarium bloodstream infection in an eleven-year-old male patient treated for high-risk acute lymphoblastic leukaemia. The patient presented with neutropenic fever and necrotic papular skin lesions. Fusarium solani complex was identified in blood cultures. Initial empirical therapy with voriconazole led to partial improvement, but therapeutic drug monitoring showed persistently low plasma levels. Genetic analysis revealed CYP2C19*17 polymorphism, classifying the patient as an ultrarapid metabolizer. Treatment was switched to liposomal amphotericin B, resulting in clinical recovery. Conclusion: This case highlighted the importance of early diagnosis, targeted antifungal treatment, therapeutic drug monitoring, and pharmacogenetic testing in pediatric Fusarium infections.