Antibiotic Prophylaxis and Renal Damage In Congenital Abnormalities of the Kidney and Urinary Tract

Inclusion Criteria: * Age between 1 and 4 months (\> 4 weeks and \<20 weeks of post-natal age) * Gestational age \> 35 weeks * Glomerular filtration rate (calculated according to Schwartz) \> 15 ml/min/1.73 m2 * No previous symptomatic UTI * Imaging Diagnostic work-up completed and presence of grade III to V vesicoureteral reflux * Informed consent of parents Exclusion Criteria: * Age \<1 and \>4 months * Gestational age \< 35 weeks * Glomerular filtration rate (calculated according to Schwartz) \< 15 ml/min/1.73 m2 at three months of age * Patients with neurogenic bladder, myelomeningocele, ureteropelvic junction and/or ureterovesical junction obstruction, or other malformations leading to potential voiding disturbances. * Presence of urethral valves * Patients with no or low grade reflux (grade I and II). * Hypersensitivity to the all the utilized antimicrobial agent * Children with serious clinical conditions which, according to the investigator, prevent them from being included in the study cohort. * Use of experimental drugs in the month previous to the beginning of the study * Children unable to follow the established protocol procedures or whose parents are unable to sign the informed consent.