The following is a summary of “Clinical value of Aspergillus-specific IgG antibody test in the diagnosis of nonneutropenic invasive pulmonary aspergillosis,” published in the June 2023 issue of the Clinical Microbiology and Infection by Lu et al.
Aspergillus-specific IgG antibody (Asp IgG) has been used effectively to diagnose chronic pulmonary aspergillosis. Researchers investigated its value in nonneutropenic invasive pulmonary aspergillosis (IPA) through a prospective, multicenter, and controlled study. From February 2015 to August 2022, they enrolled 372 patients with clinically suspected nonneutropenic IPA. After excluding 4 cases with Aspergillus colonization, the remaining 368 cases were confirmed to be patients with IPA (n = 99) or non-IPA patients (n = 269) with community-acquired pneumonia (n = 206), tuberculosis (n = 22), nontuberculous mycobacteria (n = 5), lung abscess (n = 6), or noninfectious diseases (n = 30). Asp IgG in plasma samples was evaluated using an enzyme-linked immunosorbent assay.
At a cut-off value of ≥80 AU/mL, Asp IgG had much higher sensitivity (59.6% vs. 19.2%, P < 0.0001) but lower specificity (77.0% vs. 96.3%, P < 0.0001) than serum galactomannan (GM) (cut-off value of ≥1.0), and similar sensitivity (59.6% vs. 55.6%, P = 0.611) but lower specificity (77.0% vs. 91.2%, P = 0.001) than bronchoalveolar lavage fluid (BALF) GM (cut-off value of ≥1.0), respectively. The combination diagnosis of positive Asp IgG and BALF GM had a higher sensitivity (81.0% vs. 55.6%, P = 0.002) but lower specificity (75.2% vs. 91.0%, P = 0.001) than BALF GM alone.
The receiver operating characteristic curve revealed that the optimal diagnostic value for Asp IgG was 56.6 AU/ml, with a sensitivity of 78% and a specificity of 63%, respectively. In nonneutropenic IPA patients, the diagnostic value of Asp IgG is superior to serum GM and slightly inferior to BALF GM. It is a good screening and diagnostic method for nonneutropenic patients with IPA, particularly those who cannot tolerate invasive procedures due to the convenience of blood sampling.