Abstract
Blood and radiological tests are used to diagnose invasive aspergillosis (IA), but it remains unknown which is more useful. We recently made a prospective study to compare the usefulness of chest CT scan, latex agglutination test (LA) and determination of plasma (1→3)-beta-D-glucan (BDG) levels for IA diagnosis. Of 215 patients, 16 were diagnosed as definite IA. While sensitivities of LA and BDG were 44% and 63%, respectively, all the patients showed some abnormal signs on chest CT scans. On average, CT scans preceded LA by 7.1 days and BDG by 11.5 days. Interestingly, false-positive rate of the blood tests increased during neutropenia. Because lung is the usual portal of Aspergillus, chest CT scan may be more beneficial than the blood tests for early diagnosis of IA. Care is necessary in interpreting the results of these tests, especially when patients are neutropenic.
Blood tests must be sensitive and their results must be interpreted quantitatively. We recently developed a new quantitative diagnostic system for IA using real-time PCR. In vitro examination using 102 copies of Aspergillus DNA showed that linearity was obtained when there were more than 20 copies. We examined 323 samples taken from 122 patients with hematological malignancies. Blood samples were subjected to real-time PCR, enzyme-linked immunosorbent assay (EIA) and BDG. Sensitivity of real-time PCR, ETA and BDG was 79, 58 and 67%, respectively. Specificity of each assay was 92, 97 and 84%, respectively. Real-time PCR was highly sensitive for IA diagnosis, and quantification was accurate.
