BackgroundCritically ill patients in the intensive care unit (ICU) are at high risk for developing Clostridioides difficile infections (CDI). Risk factors predicting their mortality or standardized treatment recommendations have not been defined for this cohort. Our goal is to determine outcome and mortality associated risk factors for patients at the ICU with CDI by evaluating clinical characteristics and therapy regimens.MethodsA retrospective single-centre cohort study. One hundred forty-four patients (0.4%) with CDI-associated diarrhoea were included (total 36.477 patients admitted to 12 ICUs from January 2010 to September 2015). Eight patients without specific antibiotic therapy were excluded, so 132 patients were analysed regarding mortality, associated risk factors and therapy regimens using univariate and multivariate regression.ResultsTwenty-eight-day mortality was high in patients diagnosed with CDI (27.3%) compared to non-infected ICU patients (9%). Patients with non CDI-related sepsis (n = 40/132; 30.3%) showed further increase in 28-day mortality (45%; p = 0.003). Initially, most patients were treated with a single CDI-specific agent (n = 120/132; 90.9%), either metronidazole (orally, 35.6%; or IV, 37.1%) or vancomycin (18.2%), or with a combination of antibiotics (n = 12/132; 9.1%). Patients treated with metronidazole IV showed significantly longer duration of diarrhoea > 5 days (p = 0.006). In a multivariate regression model, metronidazole IV as initial therapy was an independent risk factor for delayed clinical cure. Immunosuppressants (p = 0.007) during ICU stay lead to increased 28-day mortality.ConclusionTreatment of CDI with solely metronidazole IV leads to a prolonged disease course in critically ill patients.