Association of antimicrobial consumption with Clostridioides difficile incidence across the departments of an academic medical centre

Background: Clostridioides difficile infection (CDI) is a common gastrointestinal disease in healthcare settings, ranging from uncomplicated diarrhoea to life-threatening pseudomembranous colitis. It is associated with increased morbidity, mortality and healthcare costs. The aim of the study was to correlate CDI incidence with total and specific antibiotic consumption across 17 clinical departments of an academic hospital. Methods: This retrospective correlation study used data on CDI and antibiotic prescriptions from 1.1.2008 to 31.12.2021. CDI episodes were defined using CDC criteria. Antibiotic consumption was reported per WHO in defined daily doses (DDD). A mixed effects logistic regression model was fitted with each department as random effect to determine CDI incidence as a function of year and adjusted for antibiotic consumption. Results: Amoxicillin-clavulanate showed the highest annual consumption across the 17 departments (median 13.5 DDD/100 patient-days). The average CDI incidence was highest in nephrology (22.3/10′000 patient-days) and lowest in otorhinolaryngology (0.1/10′000 patient-days). We observed an association between overall antimicrobial consumption and CDI incidence (incidence risk ratio (IRR) per 10 DDD/100 patient-days of 1.16, 95% confidence interval (1.09, 1.23), P<0.001). When plotting each department's CDI incidence against the departmental average annual consumption, no significant trend was found; however, there was a trend for the association between CDI and selected antibiotic usage, such as carbapenems (P=0.003), ceftriaxone (P=0.04), cefepime (P<0.001), macrolides (P<0.001) and piperacillin/tazobactam (P=0.03). Conclusions: We detected an association between antibiotic consumption and CDI incidence across the departments of an academic hospital; however, we could only correlate departmental CDI incidence with the usage of select antibiotics.