False-positive Aspergillus antigen testing due to application of piperacillin/tazobactam—is it still an issue?

We evaluated the impact of piperacillin/tazobactam (PT) therapy on galactomannan enzyme immunoassay (GEI) testing (Platelia™; Bio-Rad, Marnes La Coquette, France). Galactomannan contents of PT batches were highly variable. We found that false-positive GEI results can be avoided by performance of blood sampling before PT administration and by using separate sites for blood sampling and for administration of antibiotics.