Role of Aspergillus Galactomannan Antigen Test for the Screening of Invasive Aspergillosis in Patients with Hematological Malignancies

Background: Invasive aspergillosis (IA) is a leading cause of death among immunocompromised patients, particularly those with hematological malignancies. The use of galactomannan (GM) antigen as a biological marker for screening of IA in high-risk patients is attractive and non-invasive tool that detect evidence of IA prior to the appearance of clinical manifestations.

Objectives: The aim of this study was to compare the diagnostic value of the conventional blood culture technique to the serological detection of GM antigen using ELISA for screening of IA in neutropenic patients with hematological malignancies.

Methods: Forty patients with haematological malignancies from those admitted to the Clinical Oncology Department of Menoufia University Hospitals (MUH) were enrolled and classified to have either proven (5/40; 12.5%), probable (10/40; 25%) or possible (25/40; 62.5%) invasive aspergillosis based on the clinical criteria provided by the European Organization for research and treatment of Cancer (EORTC) and Mycoses Study Group (MSG). Blood samples were collected from all participants and subjected to conventional blood culture for isolation and identification of Aspergillus spp. ELISA technique was applied for serological detection of GM antigen in the patients’ serum samples.

Results: The sensitivity, specificity, PPV(positive predictive value) and NPV (negative predictive value of GM antigen ELISA testing were 100%, 74%, 36% and 100% respectively for both proven and probable cases. On applying the principle of test in series (the patient is positive if positive in both culture and the GM test), the results were improved to 100% sensitivity, 100% specificity, 100% PPV, 100% NPV and 100% accuracy. Galactomannan antigen testing proved excellent sensitivity (80%) compared to other clinical features and radiological criteria for diagnosis of probable aspergillosis and proved to be a good negative test.

Conclusion: With conjunction of clinical and radiological signs, Aspergillus GM test can assist physicians in the of diagnosis of IA in patients with hematological malignancies to allow initiation of effective antifungal therapy which is ultimately important in high-risk populations.