Febrile urinary tract infections (UTIs) are common in children, but there is no consensus concerning the duration of the antibiotic treatment. Current recommendations include the use of an oral antibiotic, chosen between amoxicillin and clavulanic acid or a third-generation cephalosporin (ceftibuten), for a minimum of seven to a maximum of 14 days. In an antibiotic overuse-sparing model, proper evaluation of a shorter therapy in the treatment of febrile UTI in childhood is lacking.

The objective of this randomized controlled trial is to assess the non inferiority of a five days oral course of amoxicillin and clavulanic acid vs the standard 10-day regimen in the treatment of febrile UTIs in children.

The trial results might provide evidence of the non-inferiority of a short duration of the antibiotic course for the treatment of febrile UTI in childhood, contributing to a reduction in the over-use of antibiotics and consequently limiting the emergence of antibiotic resistance.

Inclusion Criteria:

1. Age from 3 months to 5 years;
2. Clinical diagnosis of febrile UTI, defined by fever ≥38°C and positive result of urinalysis (nitrite and/or leukocyte esterase positivity) in two consecutive urine samples collected by bladder catheterization or clean catch (19). The diagnosis of UTI will be then confirmed by positive urine culture for a single type of bacterium with a charge> 105 CFU /ml as per the Recommendations of the Italian Society of Pediatric Nephrology (SINePe) (19).

Exclusion Criteria:

1. "Complicated" febrile UTI (septic appearance, repeated vomiting impeding oral administration of the antibiotic, severe-moderate dehydration with the need for intravenous antibiotic therapy)
2. Presence of an inserted urinary catheter
3. Immunodeficiency
4. Hypersensitivity to the active substance or other beta-lactam antibiotics
5. Any antibiotic treatment received in the previous 15 days.
6. Presence of another poorly controlled chronic medical condition (diabetes, inflammatory bowel disease, etc.)
7. Presence of neurological bladder
8. Presence of phenylketonuria or glucose-galactose malabsorption
9. Intestinal malabsorption
10. Poor compliance
11. History of jaundice or liver failure positive