1,3-β-d-Glucan contamination of common antimicrobials

1,3-beta-d-Glucan (BDG) is a fungal cell wall constituent used in the diagnosis of invasive fungal infections. BDG testing, although endorsed by the European Organization for Research and Treatment of Cancer, suffers from limited specificity. False-positive results have been linked to haemodialysis membranes, blood products, antineoplastic agents and antimicrobial use. The aim of this study was to determine whether false-positive BDG results in the context of antimicrobial use are caused by BDG present in infusion solutions. We obtained 35 antimicrobial drugs (30 antibiotics and 5 antifungals) and analysed their BDG content using two different assays. Twenty-five antimicrobials (20 antibiotics and all the tested antifungals) contained enough BDG to trigger a positive test. Depending on the substance, BDG varied between 9 and 2818 pg/mL. A majority of the available antimicrobial substances contained BDG, potentially limiting the utility of BDG testing in the context of prior exposure to these drugs. As the cumulative effects of repeated BDG exposure are unknown, efforts to reduce contamination should be considered.