[The value of serum galactomannan antigen for detection of invasive aspergillosis in hematological patients]

Abstract

Objective: The incidence of invasive aspergillosis (IA) is increasing in patients with hematological disorders and it may lead to a high mortality rate. This study was to evaluate serum aspergillus galactomannan (GM) antigen assay as a potential early diagnosis and follow-up of IA.

Methods: From October 2004 to October 2005, 302 blood samples were obtained from 81 neutropenic hematological patients with fever over 38.5 degrees C and shown to have no response to broad-spectrum antibiotics treatment. Blood samples were collected twice a week. The detection of aspergillus GM antigen was carried out with a sandwich enzyme-linked immunosorbent assay and a GM positivity was defined as A index > 1.5 in two consecutive mensuration. Furthermore, the patients with positive GM test received preemptive antifungal therapy with amphotericin B or itraconazole.

Results: Twenty seven patients (33.0%) were considered GM test positive from a total of 81 cases and 11 patients were diagnosed as proven or probable IA. The GM test correctly identified 7 of the 11 patients who had aspergillus antigen (63.6% sensitivity). When 14 patients without signs or symptoms of invasive fungal infection (IFI) were tested, the test correctly identified 12 of the 14 (85.7% specificity) as not having the antigen. GM positivity allowed also the anticipation of IA diagnosis (from 3 to 30 days before mycological culture). 19 of 27 GM test positive patients were given preemptive anti aspergillus therapy and there was a good response in 12 patients but no response in 7 cases with 36.8% mortality. After treatment, GM antigen decreased to normal with a good response. Otherwise, an elevated value hinted a unsatisfactory result as judged with Wilcoxon signed rank test (P < 0.0005).

Conclusions: It is suggested that serum GM antigen detection may be a useful test for early diagnosis of IA and GM test-based preemptive antifungal therapy in hematological patients at high risk can decrease mortality of IA substantively. Moreover, the dynamic change of GM test value can be useful for assessing therapeutic response.