Clinical Research Directory

INCLUSION CRITERIA: 1. Clinical suspicion of urinary tract infection irrespective of the presence of fever. 2. Clinically stable (i.e., not respiratory or circulatory affected, septic, or meningeal). 3. 4 weeks to 2 months of age (corrected age, if premature). All children who do not receive any empirical antibiotic therapy but have a positive urine culture can be included if the clinical suspicion of urinary tract infection persists. A positive urine culture is defined as: * Suprapubic bladder aspiration: any growth of bacteria. * Sterile intermittent catheterization: monoculture with ≥10\^3 colony forming units per milliliter (cfu/ml). * Midstream urine x 2: monoculture with the same bacteria in both tests with ≥10\^4 cfu/ml. * Midstream urine x 2: monoculture with the same bacteria in both tests with ≥10\^5 cfu/ml in one test and 10\^3 cfu/ml in another test. EXCLUSION CRITERIA: 1. Non-Danish civil registration number. 2. High-risk medical history. 1. Previous urinary tract infection. 2. Prophylactic antibiotic treatment. 3. Known urogenital abnormality (i.e., hydronephrosis (pyelectasis ≥10 mm or/and caliectasis ≥5 mm); hydroureter; vesicoureteral reflux; multicystic dysplasia; renal dysplasia; renal hypoplasia; renal agenesis; duplex kidney; ectopic placed kidneys; polycystic kidney disease; neurogenic bladder dysfunction; and hypospadias). 4. Previous hospitalization needing antibiotic therapy. 3. Markedly elevated c-reactive protein indicating bacteremia. 4. Elevated creatinine. 5. Oral therapy is not possible (e.g., frequent vomiting or excessive regurgitation).