Risk factors for pre- and post-engraftment bloodstream infections after allogeneic hematopoietic stem cell transplantation

Background Bloodstream infections (BSI) are frequently observed after allogeneic hematopoietic stem cell transplant (HSCT), and could cause morbidity and mortality. Methods We retrospectively evaluated the incidence, characteristics of, and risk factors for BSI at both pre‐ and post‐engraftment in 209 adult HSCT patients at our institute between June 2006 and December 2013. The median age at transplantation was 45 years (range, 15–65). A total of 122 patients received bone marrow, 68 received peripheral blood stem cells, and 19 received umbilical cord blood. Results The cumulative incidences of pre‐ and post‐engraftment BSI were 38.9% and 17.2%, respectively. Nine patients had both pre‐ and post‐engraftment BSI. In the pre‐ and post‐engraftment periods, respectively, 67.4% and 84.1% of isolates were gram‐positive bacteria (GPB), 28.3% and 11.4% were gram‐negative bacteria (GNB), and 4.3% and 4.5% were fungi. Coagulase‐negative staphylococci were the most commonly isolated GPB, while Stenotrophomonas maltophilia and Pseudomonas aeruginosa were the most commonly isolated GNB. Pre‐engraftment BSI was associated with an increased risk of death. Overall survival at day 180 for patients with or without pre‐engraftment BSI was 70.0% and 82.7%, respectively (P = 0.02). Conclusions Risk factors for BSI in the pre‐engraftment period were the interval between diagnosis and transplantation (261 days or more), engraftment failure, and high‐risk disease status at HSCT in a multivariate analysis. No significant risk factor for BSI in the post‐engraftment period was identified by a univariate analysis. These findings may be useful for deciding upon empiric antibacterial treatment for HSCT recipients.