Characteristics of the resistome and the potential for bloodstream infections in patients with gut colonization by Klebsiella pneumoniae undergoing hematopoietic stem cell transplantation

Background Hematopoietic stem cell transplantation (HSCT) patients are at high risk for intestinal colonization by Klebsiella pneumoniae (Kp), potentially leading to Kp-associated bloodstream infections (BSI). This study aims to determine the incidence of Kp colonization, the risk of its progression to Kp-BSI, and the associated risk factors in HSCT patients. Methods Between August 2022 and December 2023, perianal swab specimens were prospectively collected from HSCT recipients. Bacterial isolates were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS). Polymerase chain reaction (PCR) was employed to screen for prevalent antimicrobial resistance genes. The minimum inhibitory concentration (MIC) of colonizing strains to common antimicrobial agents was determined using the VITEK 2 automated system (bioMérieux, France). Risk factors associated with Kp colonization and subsequent BSI were analyzed by logistic regression. Results Among 409 HSCT recipients, 112 (27.4%) demonstrated pre-transplant Kp colonization, including 14 cases of carbapenem-resistant Kp (CRKp). Subsequent Kp-BSI occurred in 14 colonized patients. The colonizing strains exhibited the highest susceptibility rates to carbapenems among all antimicrobial classes tested. Multivariate analysis identified the following independent risk factors for Kp colonization: higher Hematopoietic Cell Transplantation Comorbidity Index (HCT-CI), fever, and use of posaconazole, acyclovir, and proton pump inhibitors (omeprazole). Colonized patients had a significantly higher risk of developing Kp-BSI within 100 days post-HSCT ( P < 0.0001). Conclusions Kp colonization significantly increases the risk of subsequent BSI in HSCT patients. Studies have found that rational management of non-antibacterial drugs (such as strictly evaluating the indications for proton pump inhibitors) can reduce the incidence of Kp colonization. Our data suggest that it is necessary to enhance awareness of the risks associated with bacterial colonization before transplantation.