Aspergillus and Aspergillosis

The genus Aspergillus contains about 180 validly described saprophytic species. Nearly 10 percent of these species can cause a wide spectrum of infectious disease including life threatening invasive aspergillosis, colonization of the sinus and respiratory organs as well as allergic diseases. Cases of life threatening invasive aspergillosis have been steadily rising throughout the world. While prophylactic antifungal drugs have reduced the mortality due to invasive aspergillosis in immunosuppressed and immunodeficient patients, the overall case fatality rate remains well above 50% making it one of the most difficult microbial diseases to manage. A. fumigatus is by far the most common cause of invasive aspergillosis regardless of the underlying conditions of patients. Old concepts regarding the identification of Aspergillus species have strictly been based on morphological characteristics which have often been problematic due to their variability. The new classification concept employs phenotypic characteristics with multigene DNA sequences. The new method allowed differentiation of genetically distinct but morphologically similar sister species of A. fumigatus. The recently described A. lentinus is one such example which had previously been identified as A. fumigatus. Clinical diagnosis of invasive aspergillosis without waiting for isolation of culture has also made significant progress during the past 10 years. This lecture will focus on recent developments in the diagnosis of aspergillosis and the biological characteristics of A. fumigatus which renders it to be the primary cause of invasive aspergillosis. [Kor J Med Mycol 2007; 12(1): 31-56] Invited Lecture