Clostridioides difficile infection in patients with and without COVID-19 during the pandemic: A retrospective cohort study from a tertiary referral hospital.

Objectives: This study aims to detect the prevalence and specific characteristics of Clostridioides difficile infection (CDI) during the COVID-19 pandemic.

Methods: In this retrospective observational study, conducted in a tertiary hospital in Greece between May 2021 and October 2022, patients with CDI from COVID-19 and Internal Medicine wards were enrolled and compared based on epidemiological and disease-associated data.

Results: In total, 4322 patients were admitted, and 435 samples for CDI were analyzed, with 104/435 (23.9 %) sample positivity and 2.4 % prevalence. We observed an increased prevalence of CDI compared to the beginning of the COVID-19 pandemic (prevalence = 1.7 %, p = 0.003). 35.6 % of the CDI patients were hospitalized in the COVID-19 ward and 64.4 % in the Internal Medicine ward. COVID-19 patients were younger (p = 0.02) with a lower Charlson Comorbidity Index (CCI) compared to the Internal Medicine ward patients (p < 0.001). With regards to the origin of CDI cases, in the Internal Medicine ward, 68.7 % presented with Hospital-Onset CDI, 17.9 % with Community Onset-Healthcare Associated CDI and 13.4 % with Community Associated CDI, while in the COVID-19 ward, the respective percentages were 86.5 %, 5.4 % and 8.1 %. Finally, there was an increased CDI-related CFR (Case Fatality Ratio) in the Internal Medicine ward compared to the COVID-19 ward (28.4 % vs. 5.4 %, p = 0.001).

Conclusions: Increased CDI prevalence and testing were observed compared to the beginning of the COVID-19 pandemic. Lower CDI-related CFR was observed in patients with COVID-19, which may be credited to the patients' significantly lower median age and CCI, as well as to the majority of deaths being due to respiratory failure.