Carbapenemase-Producing Enterobacteriaceae (CPE) Colonization and the Risk of CPE Bacteremia in Hematopoietic Stem Cell Transplant Recipients

Background Carbapenemase-producing Enterobacteriaceae (CPE) are globally concerning pathogens due to limited therapeutic options. Despite the increasing incidence of CPE infections, evidence supporting effective empirical treatments for individuals undergoing hematopoietic stem cell transplantation (HSCT) remains limited. Methods From January 2019 to December 2023, individuals undergoing HSCT screened for CPE colonization via perianal swabs upon admission before HSCT were retrospectively analyzed. Culture-based identification and carbapenemase-specific polymerase chain reaction were performed. The occurence of Enterobacteriaceae bacteremia within 100 days post-HSCT was monitored. Propensity-score matching and competing risk analyses were used to evaluate the relationship between CPE colonization and bacteremia risk. Results Among 649 patients undergoing HSCT, 70 (11%) were colonized with CPE. Enterobacteriaceae bacteremia occurred in 20 (29%) CPE-colonized and 56 (10%) non-colonized individuals (p<0.001). Among these cases, 17/20 (85%) in the colonized group and 12/56 (21%) in the non-colonized group were caused by CPE (p<0.001). After 1:2 propensity-score matching, these rates remained consistent (85% vs. 22%, p=0.004). All CPE isolates recovered from blood were identical in species and carbapenemase type to those detected in pre-HSCT swabs. Competing risk analyses showed that pre-HSCT CPE colonization was significantly associated with CPE bacteremia, (subdistribution hazard ratio [sHR] 13.1, 95% confidence interval [CI] 6.27–27.3, p<0.001; after matching: sHR 19.1, 95% CI 4.42–82.20, p<0.001). Conclusion Pre-HSCT CPE colonization increases Enterobacteriaceae bacteremia risk. Routine screening and empirical CPE-directed therapy are essential to improving clinical outcomes.