Candida ciferrii, a new fluconazole-resistant yeast causing systemic mycosis in immunocompromised patients

Systemic infections related to fluconazole-resistant yeasts are increasingly observed in immunocompromised patients receiving fluconazole as a prophylactic antifungal treatment. Here, we report a case of invasive candidiasis caused by Candida ciferrii in a patient with acute myeloid leukemia and who suffered a relapse after autologous peripheral blood progenitor cell transplantation. Erythematous skin papulae and spotted pulmonary infiltrations were present. A skin biopsy led to the diagnosis of invasive candidiasis, emphasizing the diagnostic usefulness of this procedure. The yeast was identified as Candida ciferrii and in vitro susceptibility testing revealed its resistance to fluconazole. Until now, Candida ciferrii has not been known to cause invasive fungal infections in humans. Thus, we add another fungus to the list of flucanozole-resistant yeasts and suggest that in vitro susceptibility testing of isolated fungi should be performed for the selection of appropriate antimycotic drugs.