Metronidazole versus Vancomycin for a Moderate Clostridioides difficile Infection Defined by the Japanese Severity...

Objective To compare the effectiveness of initial metronidazole (MNZ) and vancomycin (VCM) for moderate Clostridioides difficile infection (CDI), as defined by the Japanese MN criteria. Methods: A single-center retrospective cohort study (2011-2025). Adult inpatients with an initial episode of moderate CDI who received oral MNZ or VCM were identified. Propensity score matching (1:1; caliper 0.2) balanced the demographics, severity indicators, comorbidities, and concomitant medications. Patients After exclusion, 376 eligible patients (MNZ, n=260; VCM, n=116) were identified and 98 matched pairs were analyzed. Results In the matched cohort, a clinical cure occurred in 59/98 (60.2%) MNZ and 63/98 (64.3%) VCM [odds ratio (OR), 0.84; 95% confidence interval (CI) 0.47-1.50; p=0.556]. Global cure occurred in 53/98 (54.1%) and 51/98 (52.0%), respectively (OR 0.921; 95% CI 0.53-1.61; p=0.775). Recurrence within two months was similar [23/98 (23.5%) vs 20/98 (20.4%); OR 0.836; 95% CI 0.42-1.65; p=0.605]. Kaplan-Meier curves for time-to-recurrence overlapped (log-rank p=0.539). Treatment switching due to worsening symptoms was uncommon (6.1% vs. 3.1%; p=0.306). Conclusion For moderate CDI classified according to the MN criteria, no statistically significant differences were observed between initial MNZ and VCM with respect to the clinical cure, global cure, or recurrence. Within the limitations of this retrospective observational study, these findings suggest that MNZ may remain a treatment option for moderate CDI in Japan, which is commonly used in clinical practice.