Laboratory Diagnosis of Aspergillosis

Kim, Sang Jae

Abstract

Aspergilli comprising less than 200 taxons are ubiquitous in the environment so that they cause a variety of illness in the susceptible individuals. The incidence of aspergillosis is rising with the increased use of antimicrobial agents and immunosuppressive drugs for treatment of malignant diseases or organ transplant recipients. Most of aspergillosis have been caused by Aspergillus fumigatus and less commonly by the other 15 species and 2 varieties. Aspergilli cause allergic disease most often in atopic individuals, charecterizing by asthma, by immediate skin reactivity against the corresponding fungal antigens, and by elevated level of total and specific IgE antibody and of specific IgG antibody. The various serological methods are useful for the diagnosis of those cases. Air space is vulnerable to the colonization of aspergilli forming fungus ball (aspergilloma), which hardly invade healthy tissue unless patients are immunosuppressive. They usually produce high level of specific antibody that can be easily detected by a simple immunodiffusion test. Invasive aspergillosis (IA) may develop in the immunocompromised hosts, who have had systemic corticosteroid therapy, are receiving cytotoxic drugs or have had a prolonged neutropenia. Organ transplantation, implantation of prosthetic devices or physiologic disorders also predispose patients to IA. Diagnosis of IA largely depends on demonstration of invading fungus in the clinical specimens derived from the affected lesions. While demonstration of specific antibody is rather disappointing for the diagnosis of IA, the various serological attempts to detect fungal antigen in serum or urine specimens of patients have shown a various degree of success.