Evaluation of diagnostic methods for invasive aspergillosis in haematological malignancy

Invasive aspergillosis (IA) remains a life-threatening infection in immunocompromised patients and is the most important cause of fungal death in cancer patients. In bone marrow transplant recipients the mortality rate is still approaching 90%. The purpose of this study was to investigate methods for the early diagnosis of invasive aspergillosis in patients with haematological malignancy, and to examine the best strategy for sampling. The study compared clinical, microbiological and histopathological data with newer diagnostic techniques such as antigen detection (Pastorex latex agglutination and sandwich ELISA tests), high resolution computed tomography (CT) scanning and the polymerase chain reaction. The research involved both a retrospective and a prospective study. The initial retrospective study was performed over 24 months. During this time, 38 bronchoalveolar lavage (BAL) fluid and 178 serum samples were collected from 38 febrile neutropenic and bone marrow transplant (BMT) patients. BAL and serum samples from 12 immunocompetent and 20 asymptomatic HIV+ patients were used as controls. The results suggested that the sandwich ELISA provides a simple, effective and rapid screening test. The relatively high negative predictive value of all these investigations may allow for better use of empirical antifungal therapy. Regular prospective monitoring of sequential serum samples with BAL and CT scanning in high risk immunocompromised patients allows for the earlier diagnosis of invasive aspergillosis. Based on the promising findings of the retrospective study, a one year prospective study was performed. However, the prospective study results suggests that effective prophylaxis with itraconazole may be superior to pre-emptive therapy, even at an early stage of infection