First report of bloodstream infection caused by Apiotrichum veenhuisii in a patient with acute lymphoblastic leukemia.

Apiotrichum veenhuisii (A. veenhuisii), a type of yeast found widely in nature, is a rare pathogen that induces human infection globally. Here, we report a case of a female patient with recurrent B-cell acute lymphoblastic leukemia (B-ALL) who developed severe febrile neutropenia following systemic chemotherapy. In the meantime, a certain species of fungus was repeatedly detected in her peripheral blood and bone marrow cultures. This strain was ultimately identified as A. veenhuisii through morphological examination and molecular genetic analysis. Fungemia was therefore diagnosed. After amphotericin B and voriconazole treatments, the patient's symptoms were resolved remarkably. No recurrent B-ALL was found in her bone marrow at 3 months of follow-up. This is the first evidence worldwide of bloodstream infection caused by A. veenhuisii in humans as far as we know. A precise aetiological diagnosis guides us on the correct path of antifungal treatment at a very early stage, making the patient recover with a favorable prognosis. Further functional annotation and phylogenetic analysis were performed after the whole genome was sequenced. This may help us better understand the biological characteristics and evolutionary relationships of this species.