Bloodstream Infections Are an Improbable Cause of Positive Serum (1,3)--D-Glucan in Hematology Patients

Ninety-one serum samples from 51 hematology patients with bacteremia infections were tested for (1,3)--D-glucan (BG). Eleven samples (15%) from 7 patients (14%) were positive for BG. Of these 7 patients with positive BG results, 4 (8%) had inva-sive aspergillosis and 3 (6%) had no invasive fungal disease. Bacteremia was an unlikely cause of the false-positive BG results. Amajor cell wall component of various clinically importantfungi is (1,3)--D-glucan (BG). Serum levels of BG are in-cluded in the updated European Organization for the Research and Treatment of Cancer-Mycoses Study Group (EORTC/MSG) diagnostic criteria for invasive fungal disease (IFD) in immuno-compromised patients (1). One of the limitations reported for the BG assay is the high number of potential causes of false-positive results, including bacterial bloodstream infections (BSIs), partic-ularly those due to Pseudomonas aeruginosa, Streptococcus pneu-moniae, orAlcaligenes faecalis (2–5). However, existing data on the frequency of false-positive BG results during BSI with the afore-mentioned bacteria are inconsistent (6–12). While older studies reported up to 66 % (10/15) of patients with a BSI due to Gram-positive cocci having more than one sample positive for BG, a more recent analysis found only one positive BG result among 70 patients with BSI and no IFD (7, 12). The aim of this study was to investigate the rate of BG positivity in patients with hematological malignancies and BSI in whom the BG assay was used for IFD screening twice per week. All the patients who were admitted to the hematology units of San Martino University Hospital and who developed a BSI be