Pre-engraftment bloodstream infection after allogeneic haematopoietic cell transplant: 18-year trends in aetiology, resistance and mortality.

Bloodstream infections (BSI) are frequent complications after allogeneic hematopoietic cell transplant (HCT). This study reports data on pre-engraftment BSI in years 2016-2021 and analyses changes in incidence, aetiology, resistance and mortality compared with two previous periods (2004-2009 and 2010-2015). In years 2004-2021, 1364 patients received HCT. De-escalation strategy for empirical antibiotic therapy was introduced in 2011. In 381 patients from years 2016-2021, the incidence of pre-engraftment BSI was 37.8%. Independent predictors of BSI were older age, AML/MDS and active disease. In 1364 patients, the incidence of BSI increased from 22% in period 1 to 38% in period 3 (p = 0.008), particularly gram-negative BSI: from 10.1% to 19.7% (p = 0.001). Among gram-negatives, resistance to third-generation cephalosporins remained stable (40.2% in period 3), while resistance to carbapenems and fluoroquinolones decreased (respectively, 12.6% and 59.8% in period 3). Seven and 30-day mortality after the first BSI decreased, respectively, from 11% in period 1 to 1.4% in period 3 and from 20.5% to 4.9% (p < 0.001 for both). Less recent transplant period was the only factor associated with higher mortality (p = 0.001). Incidence of pre-engraftment BSI is high and increased overtime, particularly for gram-negatives. Resistance rates remained stable, and mortality decreased overtime, documenting improvements in the BSI management.