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Abstract Invasive fungal infections are important causes of morbidity and mortality in patients with hematological malignancies and those who are undergoing hemopiotic stem cell transplantation (HSCT). The most significant risk factors in these settings are prolonged ad profound neutropenia and therapy with high doses of corticosteroids. The overall frequency of invasive fungal infections in patients with acute leukemia and following allogenic HSCT (the patient population at highest risk) is between 10% and 25%; the overall case fatality rate exceeds 50% and is close to 100% in disseminated infections or persistent neutropenia. While Aspergillus and Candida species traditionally accounts for the majority documented infections, recent epidemiologic trends indicate a shift towards infections by Aspergillus species, non-albicans Candida species, and previously uncommon fungi that often have little susceptibility to current antifungal agents (Andreas et al., 2002). Increased awareness among physicians, improved blood culture technique, and the advent of high-resolution imaging techniques have had considerable impact on improving the clinical diagnosis of invasive fungal infections, and major progress has been made in harmonizing disease definitions, in defining paradigms for antifungal intervention, and designing and implementing clinical trials. Despite these advances, however, invasive fungal infections remain difficult to diagnose and to manage and there is a contributing and urgent need for improved diagnosis, treatment and prevention (Andreas et al., 2002). Aetiology: Aspergillus and Candida species account for most fungal infections in cancer patients. However, life-threatening infections caused by emerging pathogens such as Trichosporon beigelii, Fusarium species, Pseudallescheria boydii, Zygomycetes (agents of mucormycosis), and Malassezia furfur are increasing in frequency The major risk factors for infections with these organisms are prolonged neutropenia and impaired cell-mediated immunity due either to the cancer or to the use of medications such as cytotoxic drugs or corticosteroids. |