Application of nucleic acid sequence-based amplification for diagnosis of and monitoring the clinical course of invasive aspergillosis in patients with hematologic diseases

Background and methods. We evaluated nucleic acid sequence-based amplification (NASBA) and a galactomannan enzyme immunosorbent assay (GM-EIA) for the diagnosis of invasive aspergillosis (IA) in neutropenic febrile patients and for monitoring of its clinical course and outcome. Blood samples were collected twice per week from 128 patients with hematologic diseases during periods of neutropenic fever after undergoing chemotherapy or hematopoietic stem cell transplantation. A total of 448 blood samples were tested. Results. There were 14 patients with IA (2 patients with proven IA and 12 with probable IA). The median index of the initial NASBA in the IA group was more than 10-fold higher than that in the non-IA group. Galactomannan antigenemia (index, >0.5) was detected with a sensitivity of 86%. In receiver-operator characteristic analysis, the cutoff index of NASBA for the presumptive diagnosis of IA was determined to be 5.0. Combination of these 2 parameters (either a GM-EIA index of ≥0.5 or a NASBA index of ≥5.0) improved the sensitivity of diagnosis to 100%. There was a close relationship between patient outcome and the kinetics of NASBA values: failure of negative conversion during treatment resulted in death in almost all cases. Conclusion. If either GM-EIA or NASBA results suggest IA, the diagnostic yield for IA could be improved, and NASBA could be a useful marker for predicting the clinical course and outcome of treatment.