Post-engraftment Bloodstream Infections After Allogeneic Hematopoietic Cell Transplantation: Risk Factors and Association with Mortality.

Background: Bloodstream infections (BSIs) are major cause of morbidity and mortality after allogeneic hematopoietic cell transplantation (allo-HCT). This study aimed to analyze the incidence, etiology, risk factors and outcomes of post-engraftment BSI in allo-HCT recipients.

Materials and methods: The retrospective study included 261 patients with documented engraftment after first allo-HCT performed from January 2018 till September 2021.

Results: Of 261 patients 29 (11.1%) developed at least one post-engraftment BSIs episode with a median time to post-engraftment BSI of 49 days (range, 1 - 158 days from the engraftment). A total of 45 pathogens were isolated from blood - 64.4% (n = 29) were represented by Gram-negative bacteria, and 35.6% (n = 16) - by Gram-positive bacteria. Secondary graft failure (hazard ratio [HR]: 39.93; 95% confidence interval [CI]: 7.64-208.74; P <0.001), secondary poor graft function (HR: 18.07; 95% CI: 3.53 - 92.44; P <0.001), and acute gut graft-versus-host-disease (GvHD) grade II-IV (HR: 29.86; 95% CI: 10.53 - 84.68; P <0.001) were associated with the higher risk of Gram-negative post-engraftment BSIs. Overall 30-day survival after post-engraftment BSIs was 71.4%. By multivariate analysis post-engraftment BSIs (HR: 3.09; 95% CI: 1.29 - 7.38; P = 0.011), and acute gut GvHD grade II-IV (HR: 6.60; 95% CI: 2.78 - 15.68; P <0.001) were associated with the higher 180-day non-relapse mortality risk.

Conclusion: Gram-negative bacteria prevailed in the etiology of post-engraftment BSIs with secondary graft failure. secondary poor graft function. and acute gut GvHD being the main predisposing factors for their development. Post-engraftment BSIs were associated with the higher risk of non-relapse mortality after allo-HCT.