PI-01. Bloodstream infections in allogeneic hematopoietic stem cell transplant recipients: epidemiology, risk factors and outcomes

Summary

Introduction

Bloodstream infections (BSI) are a major cause of morbidity and mortality among allogeneic hematopoietic stem cell transplant (allo-HCT) recipients. The purpose of this study was to analyze the incidence, risk factors and the outcomes of BSI after allo-HCT.

Materials and methods

This retrospective study included 207 patients (50.7% females and 49.3% males) who underwent allo-HCT in the National Research Center for Hematology during the period from January 2018 till August 2020. Median age was 35 years (range 17-65). Matched related transplantations (MRD) were performed in 57 (27.7%) cases; matched unrelated (MUD), in 48 (23.3%); mismatched unrelated (MMUD), in 37 (18.0%); haploidentical, in 64 (31.1%). Fluoroquinolone prophylaxis was received by 97 (46.6%) patients with no extended-spectrum beta-lactamase producing bacteria obtained from rectal swabs. A single allo-HCT was performed in 193 (93.7%) cases; two or more, in 13 (6.2%). Engraftment failure was detected in 35 (17.0%) patients, and acute GvHD was documented in 53 cases (25.7%).

Results

A total of 88 (42.5%) patients developed BSI: 71 (81.0%) patients had only 1 episode, 17 (19.0%), two or more; overall number of BSI episodes was 111. Median time from allo-HCT until BSI was 13 days (range 0-283). One pathogen was isolated in 93 episodes (83.7%); two or more, in 17 cases (15.3%). Overall number of microbial isolates was 133: 78 (58.6%), Gram-negative bacteria; 54 (40.6%), Gram-positive bacteria, and Candida parapsilosis was isolated in 1 case (0.8%). The ratios of Gram-negative and Gram-positive bacteria rates were as follows: 57.0% (n=49), versus 43.0% (n=37) at the day 0 to +30; 63.6% (n=14), and 36.2% (n=8) over days +30 to +100; 75.0% (n=15), and 25.0% (n=5) by day 100 and later (p>0.05). Bloodstream isolates were represented by: Escherichia coli (28.6%, n=38), Klebsiella spp (15.0%, n=20), coagulase-negative staphylococci in 13.5% (n=18); Staphylococcus aureus, 6.8% (n=9); Enterobacter spp, 8.3% (n=11); Pseudomonas aeruginosa, 3.0% (n=4), Acinetobacter spp, 1.5% (n=2), others, 5.3% (n=7).

Stem cell donor type, GvHD prophylaxis strategy, time to neutrophil engraftment of >20 days, and engraftment failure on day +28 were significantly associated in univariate analysis with higher risk of pre-engraftment BSI, whereas donor type and acute GvHD correlated with post-engraftment BSI (Table 1). MMUD compared to MRD and time to neutrophil engraftment more than 20 days were significantly associated with the higher risk of pre-engraftment BSI in the multivariate model (HR=4.78; 95% CI 1.52-14.90; p=0.007 and HR=2.83; 95% CI 1.40-2.83; p=0.004 respectively), whereas MUD and acute GvHD correlated with post-engraftment BSI (HR=5.93; 95% CI 1.28–27.52; p=0.023 and HR=3.69 95% CI 1.42-9.52; p=0.007 respectively). The overall 30-day survival after BSI was 86.9% and no significant difference could be detected between Gram-negative, Gram-positive and polymicrobial episodes (84.0% vs 92.7% vs 81.3% respectively; p=0.375).

Table 1. Univariate analysis of pre-engraftment BSI risk factors

Conclusions

Gram-negative bacterial BSIs after allo-HCT prevailed in this study. The most significant factors of pre-engraftment BSI were MMUD transplantations and time to neutrophil engraftment of >20 days; MUD transplantations and acute GvHD were associated with higher risk of post-engraftment BSI. No significant difference in 30-day overall survival could be detected between Gram-negative, Gram-positive and polymicrobial episodes.

Keywords

Bloodstream infections, allo-HCT, risk factors.