Three cases of Candida fermentati fungemia following hematopoietic stem cell transplantation

Bloodstream infection with non-Candida albicans Candida species is one of the serious complications among patients with hematological malignancies who receive long-term prophylactic antifungal agents. Here we describe three cases of Candida fermentati (C. fermentati) candidemia after allogeneic stem cell transplantation for hematological malignancies. Case 1 is fluconazole-breakthrough C. fermentati fungemia, which was well controlled with liposomal amphotericin B. Case 2 and 3 were caspofungin-breakthrough C. fermentati fungemia. In case 2, blood culture turned negative for Candida responding to liposomal amphotericin B. Although in vitro susceptibility data for the isolated pathogen suggested the efficacy of both caspofungin and liposomal amphotericin B in all three cases, clinically liposomal amphotericin B seemed to have been more effective for eradication of the pathogen from blood stream. C. fermentati needs to be considered as a possible cause for breakthrough candidemia among post-transplant patients with prolonged antifungal prophylaxis. Discrepancy between in vitro and in vivo susceptibility to antifungals, especially to echinocandins, might provide a clue for the optimal choice of antifungals for C. fermentati infections.