Trichoderma harzianum fungemia following COVID-19-related immune dysregulation in an immunocompetent patient: a case diagnosed by mNGS

Abstract Background Trichoderma harzianum is a filamentous saprophytic fungus rarely implicated in human infections. Invasive Trichoderma infections are uncommon and are typically observed in immunocompromised hosts. Case presentation We report a 68-year-old immunocompetent male farmer who developed persistent fever and dizziness after COVID-19 infection. Initial empirical antibacterial and antiviral therapy failed to relieve symptoms. Repeated blood cultures and serological fungal tests were negative, whereas metagenomic next-generation sequencing (mNGS) of whole blood identified T. harzianum sequences (794 reads), confirming fungemia. The patient experienced severe infusion reactions to amphotericin B and visual disturbances with voriconazole, but responded well to posaconazole therapy. Fever subsided within seven days, mNGS sequence reads declined markedly, and no recurrence occurred during 12 weeks of follow-up. Conclusions This case represents the first documented instance of T. harzianum fungemia in an immunocompetent individual following transient immune dysregulation associated with COVID-19. The report underscores the diagnostic value of mNGS in detecting rare opportunistic fungi when conventional cultures are negative and highlights posaconazole as a potential therapeutic option.