Secondary Oral Vancomycin Prophylaxis and

Background: Secondary oral vancomycin prophylaxis has been reported to reduce rates of recurrent Methods: This was a retrospective study of children and young adults with cancer with primary CDI episode treated from 2017 to 2024. To determine the causal impact of secondary oral vancomycin prophylaxis during antibiotic administration to prevent CDI in the 6 months after the primary episode, propensity score matching and weighted generalized estimating equations were performed. Results: The initial cohort included 163 patients who experienced primary CDI. After exclusions, 72 patients received 150 courses of broad-spectrum antibiotics within 6 months following their initial infection. Fifteen patients received 27 episodes of OVP. CDIs were not significantly decreased, occurring in 22 of 123 (17.9%) courses in patients who did not receive OVP and 2 of 27 (7.4%) in courses with prophylaxis. Propensity score matching resulted in 49 broad-spectrum antibiotic episodes from 19 patients, forming 11 matched sets. Receipt of OVP was significantly associated with reduced risk of CDI (adjusted odds ratio, 0.074 [95% confidence interval, .01-.54]). Conclusions: In this single-center retrospective study of children and young adults with cancer with primary CDI, receipt of OVP was significantly associated with reduced risk of CDI recurrence when receiving broad-spectrum antibiotic therapy. Given the small sample size and likely residual confounding, these findings should be considered hypothesis-generating pending confirmation in larger studies.