Opportunistic Fungal Infection

Opportunistic fungal infections are caused by fungi that are nonpathogenic in the immunocompetent host, many of which are part of the normal upper respiratory tract flora. These organisms may cause pulmonary infection in immunocompromised hosts. Immunocompromised patients and patients with febrile neutropenia with opportunistic fungal infections may have normal chest radiographs. Thus, chest CT should be performed for further evaluation. Imaging abnormalities in this patient population should raise suspicion for opportunistic infection. Neutropenia is the single most important risk factor for Aspergillosis. Aspergillus is the most common opportunistic infection in patients with hematologic malignancy and bone marrow transplantation. Aspergillus spp., Candida spp., and Cryptococcus spp. are the most common fungal infections in patients with solid organ transplantation. Pneumocystis jirovecii is the most common fungal infection in patients AIDS with CD4 count s<200 cells/mm3. Cryptococcal pneumonia is also common in this population. There has been a recent increase in uncommon fungal pathogens causing invasive pulmonary disease.