Evaluation of colonization with multidrug-resistant microorganisms and the incidence of attributable infections in patients undergoing hematopoietic stem cell transplantation

Background/aim: The global rise in multidrug-resistant organisms (MDROs) has led to an increased incidence of MDRO infections following hematopoietic stem cell transplantation (HSCT), particularly during the preengraftment period. The objective of this study was to evaluate the relationship between pretransplant colonization by MDROs or carbapenem-resistant Enterobacterales (CRE) and the occurrence of infections caused by phenotypically similar microorganisms during the preengraftment period, as well as to assess the clinical outcomes of patients colonized with MDROs prior to transplantation. Materials and methods: This prospective cohort study included patients diagnosed with hematological malignancies who underwent HSCT at the bone marrow transplant unit of Dr. Abdurrahman Yurtaslan Ankara Oncology Training and Research Hospital between 01 May 2023 and 30 July 2024. Weekly surveillance cultures were obtained at admission and thereafter, including axillary, inguinal, and perianal swabs for MDRO/CRE detection and stool samples for vancomycin-resistant Enterococcus (VRE) colonization. The effect of MDRO colonization on the development of infections caused by phenotypically similar MDRO pathogens during the preengraftment period was analyzed. Results: A total of 118 patients were included in the study. The infection rate with CRE pathogens in patients colonized at least once and in those without CRE colonization was 23.3% and 1.3%, respectively (p = 0.004). The incidences of sepsis (p = 0.003), septic shock (p = 0.01), intensive care unit transfer (p = 0.006), and 28-day mortality (p < 0.001) were significantly higher among patients colonized at admission. Conclusion: Early detection of CRE colonization through surveillance culture screening may facilitate timely initiation of appropriate antibiotic therapy for CRE infections during the early preengraftment period, potentially improving clinical outcomes and survival.