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Invasive aspergillosis (IA) is a frequent complication of blood or marrow transplantation. Previous studies have reported that the Aspergillus galactomannan enzyme immunoassay (GM EIA) may be a useful diagnostic tool for IA, but its sensitivity is variable. We examined the performance of the GM EIA in 986 serum samples from 67 patients. Results demonstrated that decreasing the index cutoff for positivity to 0.5 increased its sensitivity, with minimal loss of specificity. The low cutoff increased the duration of test positivity before diagnosis by clinical means. Sensitivity was highest in patients who did not receive preventative mold-active antifungals (87.5%). A rabbit model demonstrated that the level of circulating antigen correlated with the tissue fungus burden. A quantifiable response to antifungal therapy in clinical samples and the rabbit model supports the development of this assay for early diagnosis and therapeutic monitoring. The 0.5 cutoff may allow for better performance as an early diagnostic test.

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Aspergillus antigenemia was followed up in 215 consecutively observed bone marrow transplant (BMT) patients over a period of two years, using both a latex agglutination test and a sandwich immunocapture enzyme immunoassay (EIA) with a rat antigalactomannan monoclonal antibody as capture and detector antibody. For each patient, sequential sera (3 to 20) were obtained before and after BMT. No positivity was observed before BMT. After BMT, the EIA and latex agglutination test were positive in 19 and 4 patients respectively of 25 patients with confirmed aspergillosis and 14 and 7 of 15 patients with probable aspergillosis. In 19 of 25 patients with confirmed aspergillosis and 9 of 15 patients with probable aspergillosis, the EIA was more sensitive and detected infection earlier than the latex test. In all positive cases, antigenemia rapidly increased in sequential samples and remained strongly positive. In 31 of 169 (19%) BMT patients without clinical signs of aspergillosis, the EIA was occasionally positive in samples taken within the first month after BMT, giving a specificity of 81% in these patients. In non-BMT patients suffering from other diseases (n = 77), the specificity was 98.7%. The overall positive and negative predictive values for the EIA were 54% and 95% respectively. These results favour the use of EIA for early diagnosis and monitoring of aspergillosis in BMT patients, although the predictive value of transient positivity remains to be ascertained.