Epidemiology and impact of colonization by multidrug-resistant Gram-negative bacteria on bloodstream infections in early phase of allogeneic hematopoietic stem cell transplantation

Objective. To study epidemiology and impact of colonization by multidrug-resistant Gram-negative bacteria (MDRGNB) on bloodstream infections (BSI) during allogeneic hematopoietic stem cell transplantation (allo-HSCT). Materials and Methods. The retrospective study included 288 patients received the first allo-HSCT between 2018 and 2019. The median age was 32 (18–66) years, male – 53% (n = 152). The majority of patients had acute leukemia – 62% (n = 178) and received transplant from matched unrelated – 42% (n = 120) or haploidentical donor – 26% (n = 75). Relapse of underlying disease at the moment of all-HSCT was registered in 23% (n = 66) of patients. Results. Colonization of non-sterile sites before allo-HSCT by at least one MDRGNB was detected in 28% (n = 64). In most cases resistance is due to extended spectrum beta-lactamases (ESBL) – 86% (n = 55), while carbapenemases in combination with ESBL were detected in 14% (n = 9) of patients. After allo-HSCT the colonization was significantly higher than before transplantation (n = 161, 56%, p = 0.001), mainly due to carbapenemase- and ESBL-producing bacteria – 73% (n = 118) (p = 0.001). BSI in the early period after transplantation developed in 26% (n = 76), and in 56% (n = 43) was caused by MDRGNB. The etiology of BSI included K. pneumoniae – 51% in mostly cases. The etiology of BSI was the same bacteria that colonized non-sterile sites 2 weeks before the detection bacteria in bloodstream in 69% (n = 30) patients. Colonization by MDRGNB was associated with the development of BSI (p < 0.0001). The 100-day overall survival (OS) after all-HSCT was significantly lower in patients with colonization of non-sterile sites by MDRGNB compared with patients without colonization (60.6% vs 88.2%, p = 0.001). Conclusions. Colonization of MDRGNB after allo-HSCT reached 56%. K. pneumoniae was predominant etiology in both colonization and bloodstream infections. Colonization by MDRGNB was associated with the development of BSI and decreased OS after allo-HSCT.