Association Between Rectal Bacterial Colonization and Bloodstream Infections During Paediatric Haematopoietic Stem Cell Transplantation at A Tertiary Care Center

Background: Bloodstream infections (BSIs) remain a major cause of morbidity and mortality in paediatric haematopoietic stem cell transplantation (HSCT) recipients. Gastrointestinal colonization by multidrug-resistant (MDR) organisms has increasingly been recognized as an important reservoir for invasive infections during neutropenia and mucosal barrier injury. This study evaluated the prevalence and spectrum of bacteria colonizing the GIT and to see any association between rectal colonisation and BSI. Material and Methods: A retrospective cohort study was conducted among 100 paediatric patients who had undergone HSCT. Serial rectal swabs were obtained at admission and at Weeks 2, 4, 6, and 8 post-transplantations. Blood culture findings obtained during the same period were analyzed. Rectal colonization patterns, Enterococcus and vancomycin-resistant Enterococcus (VRE) trends, bloodstream infection profiles, and concordance between rectal and bloodstream isolates were evaluated. Descriptive and comparative analyses were performed using available statistical methods. Results: Overall bloodstream infection (BSI) incidence was 23%, with the highest incidence occurring during the first two weeks post-transplant (17%) and declining thereafter, with no BSI detected by Week 8. Early BSIs were predominantly caused by Klebsiella spp., Escherichia coli, Pseudomonas spp., and staphylococcal species, while Acinetobacter spp. emerged during later phases. Rectal colonization demonstrated progressive predominance of Enterococcus spp. and resistant Enterobacteriaceae during the transplant course. Enterococcus colonization increased significantly from 7% at baseline to 32% at Week 8 (p <0.001), with vancomycin-resistant Enterococcus emerging at Week 4 and peaking at 30%. No patient with a negative rectal swab developed bloodstream infection, although the association between concurrent rectal colonization and BSI didn’t reach statistical significance (χ²=1.59, p=0.207). A significant association was observed between underlying diagnosis and occurrence of BSI (χ²=15.30, p=0.018). Conclusion: Progressive intestinal colonization with resistant organisms occurs during paediatric HSCT and appears closely associated with subsequent bloodstream infections. Although concurrent colonization-BSI association was not statistically significant, rectal swab sterility strongly predicted absence of bacteraemia. Surveillance rectal cultures may therefore provide clinically useful information for infection-risk stratification and empirical antimicrobial decision-making in paediatric HSCT recipients.

Keywords: Paediatric Haematopoietic stem cell transplantation, bloodstream infection, rectal colonization, MDR organisms, vancomycin-resistant Enterococcus, antimicrobial resistance.