ABSTRACT
Among the estimated 1.5 million fungal species that exist in nature, few cause disease in humans or animals. Candida and Aspergillus are the principal systemic pathogens in humans; in recent years, however, more yeasts and filamentous fungi, previously thought to represent contamination or harmless colonization, have become clinically significant, particularly in compromised hosts.1-13 Their pathogenic role has become clearly established. A large European study involving over 8000 autopsies performed between 1978 and 1992 revealed a significant rise in invasive infections due to fungi other than Candida and Aspergillus.14 Most occurred in patients with aplastic syndromes or hematological malignancies, were fatal, and were not diagnosed before death. In the setting of hematopoietic stem cell transplantation (HSCT), nearly one-third of invasive fungal infections were caused by emerging opportunistic fungi other than Candida and Aspergillus.8 A steady rise was documented in mold (Aspergillus as well as non-Aspergillus) infections during the late 1990s, especially in patients who received multiple stem cell transplants.15
