Clostridium difficile is responsible for up to 25% of reported antibiotic associated diarrhea cases and virtually all cases of pseudomembranous colitis (PMC). The clinical spectrum of C. difficile infection (CDI) varies in severity from asymptomatic carriage to self-limited, mild, watery diarrhea, to PMC, intestinal perforation, toxic megacolon, sepsis, fulminant colitis, and death. In the past decade, the 027/NAP1/BI strain has emerged world-wide and has been implicated in large outbreaks with increased severity, frequent recurrence, and significant mortality. The host immune responses can influence the severity of CDI and play crucial roles in CDI onset, progression, and overall prognosis. Low serum concentrations of antibodies directed against the toxins A&B of C. difficile have been associated with a higher risk of recurrence. However, there are conflicting reports.

Inclusion Criteria:

• Hospitalized
• Suffering from diarrhea related to C. difficile
• Confirmed diagnosis of CDI
• Informed consent by the patient
• Affiliated to the social security regime

Exclusion Criteria:

• Out-patient
• No confirmed diagnosis of CDI
• Decline of participation
• Patient not affiliated to the social security regime