Female patient, 1 year and 8 months old, attends the pediatrician's office with her mother, reporting high fever (39° C) for the past five days associated with appetite loss, without other complaints. On physical examination, the child was tearful, irritable, with axillary temperature of 38,7ºC, HR: 130 bpm, RR: 35 bpm, with no change in the rest of the examination. Was performed urinalysis, complete blood count and CRP whith the following results. Urinalysis: density 1015; pH 5.5; positive nitrite; sedimentoscopy with fields full of pyocysts and rare red blood cells; no cylinders were seen. Culture of the urine was began ; CBC: Red blood cell count: 4.08 million; Hemoglobin: 11.4; hematocrit: 33.6; Platelet count: 314,000; White blood cell count: 13,800; Banded neutrophils: 0; Mature neutrophils: 59.6%; Eosinophils: 0.1%; Monocytes: 5.2%; Lymphocytes: 34.9%; CRP: 51 Result Gram and urine culture: Gram: many gram negative rods Culture:> 100,000 CFU; identified germ: E coli multidrug sensitive. Later ultrasound of the urinary tract was requested, whose images are attached.

Question:
Based on the clinical picture and the data obtained, what is the best workup?