Identification of Gut Microbiome Biomarkers Associated to Acquisition of Enterobacteriae Highly Resistant to Third Generation Cephalosporines Following Ceftriaxone Treatment.

Inclusion Criteria: * Age 18 years * Able to comply with study requirement and to provide informed consent * Outside the context of tutorship and / or guardianship, affiliated to the Social Security Regime and having consented to participate in the ARCMI study. * Patient receiving ceftriaxone (1 gram or 2 grams per day) in the emergency department Exclusion Criteria: * Patients with acute anorectal pathology incompatible with the swabbing strategy or digital rectal examination. * Prescription of another dosage of ceftriaxone (more than 2 grams per day) * Patient with inflammatory bowel disease * Allergy or contraindication to betalactamines and cephalosporins