Bloodstream infections due to Gram-negative bacteria in patients with hematologic malignancies: updated epidemiology and risk factors for multidrug-resistant strains in an Italian perspective survey

•High mortality rates in patients with hematological malignancies (HM) and bloodstream infections (BSI) caused by Gram-negative bacteria (GNB).•High prevalence of multidrug-resistant (MDR) strains among GNB causing BSI in HM patients.•Significant reduction in use of fluoroquinolone prophylaxis since 2009-2012 survey.•Increased rates of susceptibility to fluoroquinolones in most isolates and to most antibiotics tested among Pseudomonas aeruginosa isolates.•Fluoroquinolone prophylaxis and previous rectal colonization by MDR bacteria important independent risk factors for MDR GNB BSI.•Further studies needed to better understand the role of fluoroquinolone prophylaxis in countries with high prevalence of infections.