Abstract / Summary
Objectives: The clinical interpretation of molecular diagnostic results in Clostridioides difficile infection (CDI) remains challenging, particularly when polymerase chain reaction (PCR) findings are interpreted with toxin antigen results and treatment information.This study evaluated the associations of molecular findings, antibiotic therapy, and clinical severity with adverse outcomes and recurrence in hospitalized patients with CDI.Methods: We conducted a retrospective cohort study of hospitalized patients who underwent simultaneous tcdB PCR and toxin antigen testing between January 2022 and August 2025.Clinical severity was assessed using the ATLAS score.Composite adverse outcomes were defined as all-cause intensive care unit admission and/or all-cause in-hospital mortality.CDI recurrence was evaluated within 8 weeks after treatment completion.Multivariable logistic regression identified factors associated with clinical outcomes.Receiver operating characteristic analysis assessed the predictive performance of tcdB PCR cycle threshold (Ct) values.Results: Among 489 patients, the ATLAS score was independently associated with composite adverse outcomes (adjusted odds ratio [OR], 1.55 per 1-point increase; P < 0.001).CDI recurrence was independently associated with a low tcdB PCR Ct value (≤ 27.2; adjusted OR, 2.34; P = 0.005).Toxin antigen positivity was not independently associated with adverse outcomes or recurrence.Antibiotic choice between metronidazole and vancomycin was not significantly associated with recurrence.Ct values showed limited predictive performance for recurrence (area under the curve = 0.584). Conclusion:The ATLAS score was independently associated with adverse outcomes, whereas low tcdB PCR Ct values were associated with CDI recurrence.Toxin antigen results were not independently associated with either outcome.Given the limited predictive performance of Ct values, their utility for recurrence risk prediction requires further investigation.