Can Aspergillus fumigatus conidia cause false-positive results in the galactomannan enzyme immunoassay test?

INTRODUCTION:  Several factors can cause false-positive results in the galactomannan (GM) test; however, others remain unknown. Presently, the impact of airborne contamination by Aspergillus conidia during enzyme-linked immunosorbent assay (ELISA) remains uninvestigated.

METHODS:  We studied 12 A. fumigatus isolates. Fungal conidia were serially diluted and tested for GM detection using the Platelia® Aspergillus enzyme immunoassay (EIA).

RESULTS:  The conidia concentration required for an EIA-positive result was 4.8 × 10³ (median).

CONCLUSIONS:  This is the first study to evaluate the impact of environmental contamination on the Platelia® Aspergillus EIA assay. Only massive contamination can interfere with GM optical readings, suggesting that environmental contamination does not cause false-positive test results.

Keywords:
Invasive aspergillosis; Diagnosis; Platelia® Aspergillus EIA; Galactomannan; Air quality