Incidence of Bloodstream Infections after Hematopoietic Stem Cell Transplantation for Hurler Syndrome

Abstract

Mucopolysaccharidosis type I (MPS I) is a rare genetic disorder characterized by the deficiency of the alpha-L-iduronidase enzyme necessary for the degradation of glycosaminoglycans (GAG) in the lysosome. Hurler syndrome is the most severe form of MPS I, manifesting as multiorgan dysfunction, cognitive delay, and death, usually within ten years if left untreated. Hematopoietic stem cell transplantation (HSCT) is the optimal treatment option, providing a permanent solution to enzyme deficiency and halting cognitive decline; however, the HSCT complications transplantation-associated thrombotic microangiopathy (TA-TMA) and graft-versus-host disease (GVHD) are known risk factors for bloodstream infection (BSI). BSI is a serious complication of HSCT, contributing to poor outcomes and transplantation-related morbidity. There are little data evaluating BSI after HSCT in the Hurler syndrome population. We performed a retrospective analysis of patients with Hurler syndrome who underwent HSCT at our center between 2013 and 2020 to determine the incidence of BSI within the first year post-transplantation. Patient BSI data were collected through the first year post-HSCT. Variables including patient demographics and transplantation-related characteristics were collected, including information on BSI and mortality. Twenty-five patients with a total of 28 HSCTs were included in the analysis; the majority (n=17; 68%) were male, with a median age of 1.1 years (interquartile range, .35 to 1.44 years) at the time of transplantation. The most common graft source was cord blood (n=15; 54%), followed by bone marrow (n=13; 46%), with the majority from matched unrelated donors (n=14; 52%) and mismatched unrelated donors (n=13; 44%). Sixteen BSIs were diagnosed in 12 patients (48%). Most infections (n=7; 43.8%) were diagnosed in the first 20 days post-transplantation, with fewer infections observed at later time points. Seven of the 9 Hurler patients diagnosed with TA-TMA (78%) also had a BSI. The incidence rate of BSIs in Hurler patients (n=12; 48%) was higher than the rates reported in the general pediatric HSCT population at 1-year post-transplantation (15% to 35%). Given the high rate of both TA-TMA and a BSI in Hurler patients, we suspect a possible correlation between the 2. Additionally, due to the time it takes for GAG levels to normalize post-HSCT in Hurler patients, it is reasonable to suspect that the high BSI rates in these patients are linked to their Hurler diagnosis. These findings bring awareness to possible disease-related factors contributing to high BSI rates in the Hurler population post-HSCT.