Bloodstream infection (ICS) is the most common infectious complication after hematopoietic cell transplantation (TCH) and is associated with high mortality, especially in the presence of multidrug resistance (MDR). Risk factors include neutropenia, central venous catheter use, and graft-versus-host disease, varying according to the post-transplant phase. This study analyzes the frequency, etiology, and risk factors for ICS, comparing three post-TCH periods: up to D+30, between D+30 and D+100, and after D+100. From a cohort of patients who underwent allo-TCH between 2016 and 2024, 312 patients who underwent a total of 328 allo-TCH procedures were analyzed, with a median age of 41 years. Myeloid leukemias (n = 108) and acute lymphoid leukemias (n = 71) were the most prevalent diseases. Haploidentical, unrelated, and related donors accounted for 43%, 30%, and 27% of cases, respectively. During follow-up, 170 patients developed ICS, with a median time to the first ICS of 13 days after TCH, totaling 242 ICS episodes. Of these, 29 (12%) were polymicrobial. Gram-negative bacilli (BGn) and Gram-positive cocci were identified in 63% and 35% of cases, respectively, in addition to 17 episodes of fungemia (5%). In all phases, BGn predominated (64%, 58%, and 61% up to D+30, between D+30 and D+100, and after D+100, respectively), with the most frequent organisms being K. pneumoniae (Kp; n = 54), P. aeruginosa (n = 34), and E. coli (n = 27). Kp was the most frequently isolated BGn regardless of phase (24%, 24%, and 21%), but E. coli was more common up to D+30 (19%, 2%, 9%; p = 0.006), while P. aeruginosa predominated in later phases (6%, 14%, 18%; p = 0.035). Regarding MDR, 33% of Kp isolates (with an MBL pattern in 19%) produced carbapenemase, and 36% of Enterococcus isolates were vancomycin-resistant. There were no phase-dependent differences in MDR occurrence. Neutropenia was present in 63% of ICS and was a risk factor in the early phase up to D+30 (88%, 33%, 43%; p < 0.001) and for ICS caused by E. coli (19% vs. 4%; p = 0.01). Regarding CVCs, 95% of ICS events occurred with a CVC in place, limiting analysis. The presence of neutropenia was not associated with a higher frequency of CRE or VRE. ICS was frequent, with a predominance of BGn in all post-TCH phases, although with different pathogens in each phase. MDR rates were high, particularly among Kp and Enterococcus. Neutropenia was mainly associated with E. coli and with the early post-transplant phase. Knowledge of infection patterns after HCT is essential for antimicrobial management, especially for guiding initial empirical therapy.
Fernandes et al. (Sun,) studied this question.