Novel ELISA Detects Invasive Aspergillosis

Aspergillus spp. is a ubiquitous sac fungus, which is found in soil or compost or on damp walls. Inhalation of spores can lead to severe infections in individuals with a weakened immune system.

In invasive aspergillosis (IA) the fungus spreads from the lungs to other parts of the body such as the nervous system, eyes, heart, kidneys and skin. Infections affecting the nervous system are nearly always fatal. Patients with neutropenia, leukaemia, or septic granulomatosis are especially at risk of IA.

Invasive aspergillosis is also a frequent complication in advanced AIDS or following chemotherapy or bone marrow or organ transplants. Early diagnosis and prompt treatment are crucial for survival. Since clinical and radiological signs of IA are often non-specific, additional diagnostics tests such as antigen detection and culture are nearly always required to substantiate diagnosis.

A CE-marked assay, Aspergillus Antigen ELISA (EUROIMMUN, Luebeck, Germany) is based on a monoclonal antibody for the detection of the Aspergillus-specific galactomannoprotein, which is produced during active fungal growth. The analysis is performed on patient serum or bronchoalveolar lavage (BAL) fluid. Results can be evaluated either quantitatively in pg/mL using a six-point calibration curve or semi-quantitatively by means of a cut-off ratio. Semi-automated processing is available, for example using the EUROIMMUN Analyzer I.

In the most comprehensive clinical study to date, carried out by the Ludwig-Maximilians-Universität München (Munich, Germany) based on 120 sera from 45 patients with proven IA as well as control sera, the EUROIMMUN Aspergillus Antigen ELISA yielded comparable sensitivity and specificity to another commercially available Aspergillus antigen test the Platelia Aspergillus Ag Assay. The EUROIMMUN assay identified 56% of the cases, while the Bio-Rad test detected 47%. The specificity amounted to 97% for the EUROIMMUN assay and 99% for the Bio-Rad test. To overcome the relatively low sensitivity of Aspergillus antigen detection, the authors recommend serial testing of patients at risk. The original study was published on June 25, 2019, in the Journal of Clinical Microbiology.