Clostridioides difficile (formerly Clostridium) is a bacterium found in the form of spores (resistance form) in the environment to which patients may be exposed. This bacterium used to belong to the Clostridium genus, but analysis of its 16S ribosomal RNA in 2016 led to its being distinguished from it. Once the spore has been ingested, it can germinate in vegetative form (the active form of the bacterium), taking on the appearance of a Gram-positive bacillus that will colonize the digestive microbiota. This preliminary stage of digestive colonization by the bacteria is facilitated by certain factors, notably nasogastric probing, antacids, etc. Antibiotics, for their part, disrupt the bacteria of the digestive microbiota (dysbiosis), thus facilitating the implantation of C. difficile. Certain strains (known as toxigenic) will produce the main virulence factors: toxins A (TcdA) and B (TcdB) ± a third toxin (binary toxin or CDT), and thus cause the main clinical signs of digestive infection, particularly in patients with risk factors for C. difficile infection (progressive cancer, immunodepression, etc.).

Clostridioides difficile infection (CDI) is characterized by variable clinical presentations, ranging from simple watery diarrhea without colitis, which often resolves spontaneously, to severe forms with complications such as pseudomembranous colitis, intestinal perforation or septic shock, which have a very poor prognosis.

Management of this type of CDI relies mainly on the oral administration of anti-clostridium difficile antibiotics such as fidaxomicin (FDX) or vancomycin (VAN) for 10 days, as recommended by the European ESCMID, British and American IDSA guidelines. Oral metronidazole is recommended only in the absence of availability of the first two molecules (community use). Despite this treatment, one of the main characteristics of CDI is a high recurrence rate, which can reach 25% of cases. With FDX, recurrence rates appear to be lower, especially as its administration regimen is optimized. Nevertheless, its high cost is a barrier to its wider use.

In view of the high cost to the community of treating recurrences, and the reduced quality of life of patients suffering from these recurrences, which are sometimes multiple and highly incapacitating, reducing the occurrence of recurrences is a major challenge. A better understanding of the factors leading to recurrence is therefore a prerequisite for optimizing CDI prevention and treatment strategies.

The study of colonic mucosal immunity (aimed at quantifying IgA in stools) could also contribute to a better understanding of patient progress.

All these issues surrounding CDI and its management justify the setting up of a prospective cohort for the longitudinal follow-up of infected patients, enabling us to study the digestive clearance of the bacteria according to various factors, notably the digestive microbiota and the mucosal immune response.

Inclusion Criteria:

• Patients over 18 years of age
• Patients hospitalized in a department of GH Paris Saint-Joseph with a microbiologically documented Clostridioides difficile infection or a microbiologically documented Clostridioides difficile recurrence.
• Patient to be treated for Clostridioides difficile infection
• French-speaking patient
• Patients who do not object to their participation in the study

Exclusion Criteria:

• Patients under guardianship or curatorship
• Patient deprived of liberty
• Patient under court protection
• Pregnant or breast-feeding patient

Patients hospitalized in a department of Hôpital Paris Saint-Joseph with microbiologically documented Clostridioides difficile infection or microbiologically documented recurrence of Clostridioides difficile infection, for whom treatment of Clostridioides difficile infection is to be initiated.