Carbapenem-Resistant Klebsiella pneumoniae Colonization and Subsequent Infection in a Hematopoietic Stem Cell Transplantation Unit

Objective: To determine the patient-level frequency of rectal carbapenem-resistant Klebsiella pneumoniae (CRKP) colonization in an adult hematopoietic stem cell transplantation unit and describe the frequency, timing, and outcomes of subsequent clinical CRKP infection. Methods: This single-center retrospective cohort study included adults undergoing rectal CRKP surveillance at admission and weekly during hospitalization between August 2023 and February 2026. Patients with known CRKP colonization before admission were excluded. Colonized patients were evaluated for subsequent CRKP infection, defined as CRKP isolation from a clinical specimen obtained after the first positive rectal culture together with compatible clinical findings. Fisher’s exact test and exploratory Kaplan–Meier analyses were performed. Results: Among 188 patients, rectal CRKP colonization was detected in 10 (5.3%). Six colonized patients (60.0%) developed a subsequent clinical infection after a median of 14.5 days; 4 infections occurred within 15 days and all within 31 days. No clinical CRKP infection occurred among the 178 patients without detected colonization (60.0% vs 0.0%; P < .001). Bacteremia occurred in 2 colonized patients (20.0%). Six colonized patients died; all-cause mortality was numerically higher among those with infection than among those without infection (83.3% vs 25.0%; P = .19). Median infection-free survival and overall survival after colonization were 28 and 136 days, respectively. Conclusion: Rectal CRKP colonization was uncommon but identified patients at substantial risk of early clinical infection. Surveillance results may support clinical monitoring and infection-control measures but should not be used alone to guide antimicrobial treatment. Cite this article as: Kaya SY, Çelik ÖF, Arsu HY, et al. Carbapenem-resistant Klebsiella pneumoniae colonization and subsequent infection in a hematopoietic stem cell transplantation unit. Cerrahpaşa Med J 2026, 50, 0134, doi: 10.5152/cjm.2026.26134.