Study of Gut Microbiota Diversity in Children Aged 1-3 Years on Prolonged Antibiotic Prophylaxis for Grade 3 or Higher Vesicoureteral Reflux Compared With 2 Age-matched Control Groups

Inclusion Criteria: * The patient must be a member or beneficiary of a health insurance plan * Patient with no objection to participation in the study from the parent or guardian * Child with a diversified diet. o Specific inclusion criteria for group 1 (cases): * Child with grade 3 or higher vesicoureteral reflux. * Child on trimethoprim-sulfamethoxazole therapy for at least 5 months. o Specific inclusion criteria for group 2 (controls): * Child with uropathy and without long-term trimethoprim-sulfamethoxazole treatment. o Specific inclusion criteria for group 3 (healthy controls): * Child without uropathy or long-term trimethoprim-sulfamethoxazole treatment. Exclusion Criteria: * Chronic digestive pathology * Acute gastroenteritis or infectious colitis within last 15 days. * Curative antibiotic therapy taken less than one month ago. * Chronic inflammatory bowel disease or other localizations * Congenital or acquired immune deficiency (current treatment with methotrexate, biotherapies, immunosuppressants) * Patient participating in a category 1 trial likely to modify the intestinal microbiota. * Patient in an exclusion period determined by another study. * Patient under court protection, guardianship or curatorship. * Patient for whom it is impossible to give informed information to person with parental authority.