<i>Clostridioides difficile</i> Colonization and Infection in Pediatric Oncology and Stem Cell Transplant Patients

Abstract Background Pediatric oncology and hematopoietic stem cell transplant (HSCT) patients have elevated risk for Clostridioides difficile infection (CDI), which can prolong hospitalization and delay chemotherapy. Colonization is an important prelude to symptomatic CDI. We sought to characterize colonization status in these patients. Methods We retrospectively studied 276 stools longitudinally collected over 34 months from 32 HSCT and 12 oncology patients treated at a single tertiary center. Specimens were cultured for C difficile and compared by whole genome sequencing. The fecal microbiome was characterized by 16S rRNA gene sequencing. Results Baseline cultures were positive in 16 (50%) HSCT patients and 2 (12%) oncology. On subsequent samples, 64% of patients who were initially negative acquired colonization: 8 of 15 (53%) HSCT and 8 of 10 (80%) oncology. Nine clonal strains and 25 multilocus sequence types were identified by whole genome sequencing, with 4 clones found in both cohorts. Nine patients had different strains at different time points. Seven clonal strains were found in multiple patients. Seven (15.9%) patients had symptomatic CDI. C difficile–positive stools had greater microbial diversity than negative stools in both the oncology cohort (Simpson diversity index, 0.07; 95% CI, .01–.14; P = .03) and the HSCT cohort (0.15; 95% CI, .07–.24; P < .001). Conclusions C difficile acquisition and colonization are common in pediatric oncology and HSCT patients. The high prevalence of clonally related strains in multiple patients suggests that asymptomatic patients may be important reservoirs of this pathogen and lead to symptomatic CDI in some patients. Gut microbial composition may influence the risk of colonization.