Invasive Aspergillus infections in hematologic malignancy patients

The incidence of invasive Aspergillus (IA) infections in patients with hematologic malignancies continues to increase. The most common species include Aspergillus fumigatus (approximately 90% of cases), A. flavus, A. niger, A. terreus, and A. nidulans. Most infections involve the pulmonary parenchyma, though systemic dissemination of the fungus from a primary pulmonary focus or the paranasal sinuses after hyphal invasion into blood vessels is frequent. Early diagnosis and initiation of appropriate antifungal therapy has been shown to improve the prognosis of patients afflicted with this condition. The definitive diagnosis of IA is based on showing the hyphal invasion in tissue specimens together with a positive culture for Aspergillus species from the same specimen. The detection of circulating fungal antigens and DNA seems to be a promising, rapid, and sensitive diagnostic tool for early diagnosis of aspergillosis. The current antifungals available for the treatment of IA include amphotericin B deoxycholate and lipid formulations, itraconazole and caspofungin acetate. New investigational antifungal drugs include the triazoles voriconazole, posaconazole and ravuconazole, liposomal nystatin, and 2 echinocandin derivatives (anidulafungin [VER-002] and micafungin [FK463]). Preventive measures include reduction of environmental exposure of patients from sources of infection and antifungal prophylaxis. Specialized air-handling systems capable of excluding Aspergillus spores, such as high-efficiency particulate air (HEPA) filtration with or without laminar air flow ventilation has proven to be very efficacious. Targeted antifungal prophylaxis for hematologic patients who are at high risk for developing invasive fungal infections is not currently standardized.