LAUSR

Abstract Background Hematopoietic cell transplant (HCT) recipients are at a significantly greater risk for invasive pneumococcal disease than the general population. However, pneumococcal colonization in pediatric HCT recipients has not been widely studied. We evaluated the dynamics of pneumococcal colonization in pediatric patients undergoing HSCT from conditioning regimen to 100 days post HCT. Methods Mid-turbinate samples obtained from pediatric patients undergoing HCT at Children’s Mercy from September 2015 to January 2017 were tested for Streptococcus pneumoniae colonization via real-time PCR using lytA primer (autolysin-A-encoding gene). A cycle threshold value ≤35 was considered positive. First sample was obtained during conditioning regimen (week 1), second sample after HCT (week 2). Then, weekly samples were obtained for the first 100 days after HSCT. Results Twenty-two patients were included, representing 266 mid-turbinate samples. The median age at the time of HSCT was 9.5 years (IQR 3–16), and 14 patients were male (63.6%). The indication for HSCT was oncologic (15, 68.2%), hematologic (5, 22.7%) and immune deficiency (2, 9.1%). Fourteen patients (63.6%) underwent allogenic HSCT. Six patients had documentation in our electronic medical record system of receiving ≥ 1 pneumococcal conjugate vaccine prior to conditioning regimen. Nine (40.9%) of 22 patients were colonized with S. pneumoniae, their median age was 14 years (IQR 2.5–16). Pneumococcal colonization during conditioning regimen was 9% (2/22). Pneumococcal colonization from week 14 to week 16 was 42% (5/12). Conclusion A third of pediatric HCT recipients were colonized with S. pneumoniae. Pneumococcal colonization was mainly identified either at the time of conditioning regimen or toward the end of the first 100 days after HCT, with the latter being the most common. Disclosures All authors: No reported disclosures.