Efficacy of Omadacycline or Vancomycin Combined With Germinants for Preventing Clostridioides difficile Relapse in a Murine Model.

BACKGROUND: Clostridioides difficile infections (CDI) and recurrence (rCDI) are major health care burdens. Recurrence is likely caused by spores in the gastrointestinal tract that germinate after antibiotic therapy. This murine study explores germinant-antibiotic combinations for CDI. METHODS: Previously described murine models were evaluated using C. difficile VPI 10463. The severe model compared omadacycline versus vancomycin in survival, weight loss, clinical scoring, and C. difficile toxin production. The nonsevere model compared these antibiotics with and without germinants (solution of sodium taurocholate, taurine, sodium docusate, calcium gluconate). Additionally, colon histopathology, bile acid analysis, environmental/spore shedding, and 16S sequencing was evaluated. RESULTS: In the severe model, omadacycline-treated mice had 60% survival versus 13.3% with vancomycin (hazard ratio [HR], 0.327; 95% confidence interval [CI],.126-.848; P = .015) along with decreased weight loss, and disease severity. In the nonsevere model, all mice survived with antibiotic-germinant treatment versus 60% antibiotics alone (HR, 0.109; 95% CI, .02-.410; P = .001). Omadacycline resulted in less changes in bile acids and microbiota composition. Germinant-treated mice showed no signs of rCDI, spore shedding, or significant toxin production at 15 days. CONCLUSIONS: In murine models of CDI, omadacycline improved survival versus vancomycin. Germinant-antibiotic combinations were more effective at preventing rCDI compared to antibiotics alone without inducing toxin production.