Value of galactomannan detection by sandwich enzyme-linked immunosorbent assay in the early diagnosis and follow-up of invasive aspergillosis

A new sandwich enzyme-linked immunosorbent assay (ELISA), capable of detecting 1 ng of galactomannan (GM) per ml, was prospectively evaluated for use in the diagnosis of invasive aspergillosis (IA). In the study, 723 serum samples sequentially collected from 76 immunocompromised children were analysed. The detection of GM was positive in 15 patients, and IA developed in eight of them. For seven patients, the results were considered false positives. No case of IA was observed in patients negative for GM. In this pilot study, the sensitivity, specificity, positive and negative predictive values of the test were 100%, 89%, 53% and 100% respectively. In six patients with IA, antigen detection was positive before the onset of clinical or radiological signs. Seven infected patients who cleared their antigenemia survived to aspergillosis. One patient with continuously high levels of GM died of uncontrolled infection. In spite of the possibility of false positive results, sandwich ELISA is a highly sensitive method, useful for the early diagnosis of IA and for the follow-up of infected patients.