Malassezia: is it a pulmonary pathogen in the stem cell transplant population?

Malassezia furfur is a yeast that can cause a variety of infections, most commonly in normal hosts, and also in immunocompromised hosts. This yeast typically colonizes the skin, and is the causative agent of tinea versicolor. However, in immunocompromised hosts, it can more commonly cause catheter-related fungemia or folliculitis. Pulmonary infections from Malassezia have not been commonly recognized. Unlike many other common opportunistic fungal infections in immunocompromised hosts, neutropenia and the use of broad-spectrum antibiotics do not appear to be significant risk factors for Malassezia infections in the stem cell transplant (SCT) population. Additionally, disseminated infection, despite fungemia, is uncommon. A series of patients who underwent SCT at the University of Minnesota between 2004 and 2006 were reviewed for the occurrence of suspected Malassezia infections in the post-transplant period. Four cases of possible pulmonary M. furfur infection were identified in our SCT recipients. The clinical characteristics of these patients, the infections, treatment, and outcome are described. In addition, we discuss the possible pathogenicity of this yeast in the pulmonary setting.