Bezlotoxumab CDI Prevention — SCE Infectious Diseases MCQ

Correct answer: C — Bezlotoxumab (anti-toxin B monoclonal antibody) IV infusion — given as a single dose during CDI treatment, it reduces recurrence by ~40% in high-risk patients

Bezlotoxumab is the best answer because it is the only listed adjunct with robust RCT evidence for preventing recurrent Clostridioides difficile infection. It is a human monoclonal antibody against C. difficile toxin B, given as a single intravenous infusion alongside standard CDI antibiotic treatment, particularly in patients at high risk of recurrence. NICE’s evidence review found that bezlotoxumab significantly reduced CDI recurrence at 12 weeks compared with placebo: 16.5% versus 26.6% (RR 0.62; NNT about 10), with larger benefit in higher-risk groups such as older, immunocompromised, severe CDI, or previous CDI. Zinc, vitamin D and specific probiotics such as Saccharomyces boulardii or Lactobacillus rhamnosus GG do not have comparable evidence for preventing recurrence after treated CDI, and NICE advises against recommending probiotics to prevent CDI. Important UK nuance: NICE NG199 does not recommend routine NHS use of bezlotoxumab because it was not cost-effective, but among the listed adjuncts it has the strongest clinical evidence for reducing recurrence.

Reference: NICE Guideline NG199: Clostridioides difficile infection: antimicrobial prescribing, 2021; evidence review/summary of evidence. https://www.nice.org.uk/guidance/ng199