Enteral Vancomycin as Primary Prophylaxis Against Clostridioides Difficile Infection in Critically Ill Patients

Protocol Synopsis General: Enteral vancomycin has gained attention as a promising strategy for preventing healthcare facility-onset Clostridioides difficile infection (HCFO-CDI) in patients during systemic antibiotic exposure in certain high-risk populations. However, data remain scarce for its use as primary prophylaxis. Our study aims to fill this gap and evaluate whether enteral vancomycin prophylaxis can reduce the incidence of HCFO-CDI in critically ill patients along with other relevant clinical outcomes. Study Population: Study subjects will include hospitalized subjects with significant risk factors for HCFO-CDI. Inclusion and exclusion criteria are as follows: Inclusion criteria: Adult patients with at least 72 hours of hospitalization who are on a systemic antibiotic for at least 72 hours presenting with two additional risk factors for the development of HCFO-CDI. Exclusion criteria: Subjects whose consent cannot be obtained, those with concurrent use of probiotics or metronidazole (except for empiric use), those with an expected course of antibiotic for more than 14 days, those with a prior history of CDI, etc. Study Intervention: Study subjects will be randomized into two study arms - treatment versus placebo. Those in the treatment arm will receive vancomycin 125 mg solution daily for up to five days after the last dose of systemic antibiotic. Those in the placebo arm will receive a matching placebo solution. A rectal swab will be performed on all subjects prior to randomization and at study termination or discharge to assess C. difficile colonization and the possible development of vancomycin-resistant Enterococcus colonization. Primary outcome: Incidence of HCFO-CDI, defined as symptoms of ≥ 3 loose stools or diarrhea (in the absence of laxatives or other non-CDI causes) in a 24-hour period in subjects with concurrent positive stool test for C. difficile (polymerase chain reaction \[PCR\] and stool toxin test) \> 72 hours into hospitalization. Enrollment period and sample size: First dose of enteral vancomycin or matching placebo will be administered within 72 hours of the first dose of systemic antibiotic. Study investigators will monitor the subjects for adherence and possible adverse events every 3 days until hospital discharge. We are planning 1:1 randomization of the study subjects in each group (placebo versus prophylaxis group). Utilizing a 2-sided α of 0.05 and 80% power, an estimated sample size is 176 (88 subject per arm). Sample size was determined by estimating a 0% incidence of HCFO-CDI in the prophylaxis arm and a 10% incidence of HCFO-CDI in the placebo arm based on historical and institutional data. We also anticipate a 20% drop out or attrition rate after randomization.