Fecal microbiota transplantation (FMT) is recommended in the treatment of recurrent Clostridium difficile infection (CDI). The principle is to administer a fecal suspension of a healthy subject (donor) in the digestive tract of a patient with an CDI (receiver). Donors are being clinical and laboratory screening to reduce the likelihood of pathogens transmission (infectious and other). Cytomegalovirus (CMV) is part of the examinations requested by the Agence national de sécurité du médicament et des produits de santé in the context of clinical research. A sero-matching between donor and recipient CMV is requested. This recommendation eliminates many potential donors to a recipient. To date, the frequency detection level of CMV in stool in healthy volunteers with documented positive CMV serology is not known. In addition, CMV transmission risk via the stool is not established. This study aims to determine the detection frequency of CMV in healthy volunteers stool samples selected as potential donors for a FMT and having a positive CMV serology documented