Pneumococcal colonization in pediatric patients undergoing hematopoietic cell transplantation.

Despite the increased risk of invasive pneumococcal disease among pediatric hematopoietic cell transplant (HCT) recipients, pneumococcal colonization has not been evaluated in this population. We prospectively assessed longitudinal pneumococcal colonization in 22 pediatric HCT recipients from conditioning therapy to 100 days post-HCT. A higher likelihood of pneumococcal colonization was observed in the late post-HCT period (weeks 9-14) compared with the early post-HCT period (weeks 1-8), with odds increasing with each additional week after conditioning.IMPORTANCEThis is the first study to longitudinally evaluate pneumococcal colonization in pediatric hematopoietic cell transplant (HCT) recipients from the onset of conditioning therapy to 100 days post-HCT. We found a higher likelihood of pneumococcal colonization in the late post-HCT period (weeks 9-14) compared with the early post-HCT period (weeks 1-8), with odds increasing with each additional week after conditioning. Despite study limitations, these findings provide foundational insight into early post-HCT colonization dynamics and highlight the need for larger studies to better understand the roles of antibiotic exposure and pre-HCT vaccination in reducing pneumococcal colonization.