Evaluation of colonization and infection profile in allogeneic hematopoietic stem cell transplantation recipients

Introduction: Infections are one of the main causes of death after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Material and methods: We conducted a single-center retrospective analysis of colonization and infection epidemiology in 44 patients who underwent matched related donor (MRD) allo-HSCT between 2012 and 2022. Results: Colonization was observed in 84.1% of patients before allo-HSCT. The most common location was the anus, colonized in 55.4% of patients, mostly by Klebsiella pneumoniae ESBL (+) — 28.6%. Multi-drug resistant bacteria (MDR) accounted for 50.7% of positive colonization cultures before allo-HSCT. In the post-transplantation period (i.e. up to 100 days after allo-HSCT), infections occurred in 86.4% of patients. Bacteremia was observed in 47.7% of patients, mostly caused by methicillin-resistant coagulase-negative Staphylococcus epidermidis — 39.4%. Infection of the skin and soft tissue near the central line was found in 27.3% of patients, urinary tract infections in 56.8%, and gastrointestinal infections in 38.6%. Fungal infections were reported in 31.8%. MDR pathogens accounted for 58.1% of all infecting pathogens. The most common resistance was extended-spectrum beta-lactamase (ESBL), accounting for 50.8% of all MDR strains. Viral reactivations were detected in 29.5%. 59.5% of colonized patients developed an infection with the pathogen responsible for their previous colonization. Infections with such pathogens were significantly more frequent in colonized patients than with de novo pathogens (p = 0.04). Conclusions: Colonization evaluation can be an effective tool to identify patients with a high risk of developing post-transplant infections with the colonizing pathogen, potentially resulting in a prompter implementation of targeted treatment and improved infection outcome.