Surveillance of Clostridium difficile infections: Results from a six-year retrospective study in nine hospitals of a north Italian local health authority

Clostridium difficile is an emerging cause of healthcare associated infections. In nine hospitals of an Italian Local Health Authority the episodes of C. difficile infection (CDI) were identified using the data registered by the centralized Laboratory Information System, from 2010 to 2015. CDI incidence (positive patients for A and/or B toxins per patients-days) was analysed per year, hospital, and ward. A number of cases approximately equivalent to the mean of identified cases per year were studied retrospectively to highlight the risk factors associated to CDI and their severity. Nine hundred and forty-two patients affected by CDI were identified. The overall incidence was 3.7/10,000 patients-days, with a stable trend across the six years and the highest rates observed in smaller and outlying hospitals (up to 17.8/10,000), where the admitted patients were older and the wards with the highest incidences (long-term-care: 7.6/10,000, general medicine: 5.7/10,000) were more represented. The mean age of patients in each hospital was correlated with CDI rates. Of the 101 cases selected for the retrospective study, 86.1% were healthcare associated, 10.9% community acquired; 9.1% met the criteria for recurrent case and 23.8% for severe case of CDI. The overall mortality rate was 28.7%. Comorbidity conditions occurred in 91.1%, previous exposure to antibiotics in 76.2%, and proton pump inhibitors in 77.2%. Recurrent and severe cases were significantly associated with renal insufficiency and creatinine levels ≥2 mg/dL. The survey based on the centralized laboratory data was useful to study CDI epidemiology in the different centres in order to identify possible weaknesses and plan control strategies, in particular the reinforcement of staff training, mainly targeted at compliance with contact precautions and hand hygiene.