Clostridium difficile is the first cause of nosocomial infectious diarrhea, due to its mode of transmission and its resistance in the environment.

Nosocomiality is defined by the apparition of an infection 48 hours after the patient's hospitalization. Clostridium difficile contamination occurs oro-fecally and is transmitted directly through the hand or from the contaminated environment (during care or not). By implementing prevention and optimal treatment, nosocomial infections are preventable.

A clostridium difficile infection causes an additional cost of patient care for the hospital. This additional cost is principally due to the increase of the length of the stay. It varies according to patient risk factors,and also according to the reason of the hospitalization and can vary from 300 euros (~317$) to more than 25.000 euros (26.460$).

By determining the increase in the length of the stay and the additional cost due to a clostridium difficile infection in the GHICL (Groupement des Hôpitaux de l'Institut Catholique de Lille), prevention will be valued and measures against those infections should be easier to set up.

The main objective of this study is to evaluate the additional cost of an infection by clostridium difficile.

Inclusion Criteria:

• Patients that have stayed in an hospital of the GHICL between January 2013 and September 2015.

Exclusion Criteria:

• none

Patients that have stayed in an hospital of the GHICL in 2013 and 2014