Value of antigen detection using an enzyme immunoassay in the diagnosis and prediction of invasive aspergillosis in two adult and pediatric hematology units during a 4-year prospective study

BACKGROUND. Invasive aspergillosis (LA) is a well recognized, life-threaten ing infection in neutropenic patients and stem cell transplantation recipie nts. Early diagnosis is important to achieve the best outcome for these pat ients; however, definite proof often is difficult to obtain due to counteri ndicated invasive procedures. METHODS. This study evaluated the specificity and sensitivity of the detect ion of galactomannan (GM) for the diagnostic and prediction of IA in 347 ch ildren from the Pediatric Hematology Service and 450 patients from the Bone Marrow Transplantation Unit at the Hopital Saint-Louis in Paris. Serial sc reening of Aspergillus GM circulating antigen was evaluated using a double sandwich ELISA assay (Platelia Aspergillus) on 6209 sera. Among the patient s studied, 53 presented with confirmed IA (n = 27 patients) or probable IA (n = 26 patients). RESULTS. Antigen was detected on at least two sequential sera in 48 of 53 p atients, with a sensitivity of 90.6%. GM antigenemia was detected before th e onset of radiologic signs in 31 of 48 patients (64.6%), with a mean of -8 .4 days, and before clinical symptoms in 18 of 48 patients (39.6%), with a mean of -6.9 days. In patients without IA, 44 of 744 had positive antigenem ia, resulting in a specificity of 94%. False positive results could not be related to the presence of a concurrent mucositis. CONCLUSIONS. This large, prospective study allowed the authors to define be tter the conditions for the use of GM immunocapture ELISA in surveying pati ents who are at high risk for IA. The presence of antigen has a good diagno stic value mainly when there is an increase in the titer on two consecutive sera samples. A repeated negative result is a strong argument against the diagnosis of IA; however, an awareness of the possibility of unexplained fa lse negative results is important. (C) 2001 American Cancer Society.