Bloodstream Infections and Colonization in Hematopoietic Stem Cell Transplant Recipients at a South African Center: A Retrospective Analysis

Bacterial bloodstream infections (BSIs) are a serious complication after hematopoietic stem cell transplantation (HSCT), especially when caused by multidrug-resistant (MDR) bacteria. However, data on BSIs post-HSCT from centers in sub-Saharan Africa are limited. This study aims to describe the incidence, etiology, and outcomes of BSIs, including those caused by carbapenem-resistant Enterobacterales (CRE), in both autologous and allogenic HSCT recipients in South Africa. Furthermore, this study examines the incidence and clinical impact of colonization with CRE. A retrospective analysis was performed on clinical data from HSCT recipients, transplanted between January 2018 and December 2023 at Groote Schuur Hospital (GSH) and Red Cross War Memorial Children's Hospital, the academic hospitals of the University of Cape Town. Data were extracted from the transplant unit electronic and paper patient records, Hematology Patient Registry, and the National Health Laboratory Service electronic database. Surveillance cultures were taken upon admission and subsequently repeated weekly for GSH patients. In total, 270 HSCT recipients were included: 145 underwent autologous HSCT, and 124 an allogenic HSCT. The most common indication for autologous HSCT was multiple myeloma (52%), while acute myeloid leukemia was the most frequent for allogenic HSCT (34%). The overall incidence of BSIs was 35%, with a higher rate observed in allogeneic HSCT recipients (48%) compared to autologous HSCT recipients (23%). Gram-negative bacteria were the most common pathogens, and CRE were responsible for 9% of BSIs. Carbapenem-resistant Klebsiella pneumonia spp. was the most common CRE found in BSI and rectal surveillance cultures. Surveillance cultures with CRE were detected in 19% of the HSCT recipients during admission to the transplant unit, with oxacillinase-48 (and variants) the most prevalent carbapenemase. Colonization by CRE was an independent risk factor for developing BSIs. Within 100 days post-HSCT, 25 HSCT recipients (9%) died, of whom nine (36%) had a BSI in the last 7 days of life. Bivariate analysis revealed that BSIs significantly reduced overall survival in both autologous and allogenic HSCT recipients, with a further decrease in survival when the BSI was caused by MDR bacteria. BSIs are a frequent and severe complication among HSCT recipients in South Africa, particularly in those receiving allogenic HSCT. Colonization with CRE significantly increases the risk of BSIs, underscoring the need for vigilant infection control and targeted antimicrobial strategies in this vulnerable population.