The main expected result is to identify the timing of initiation of antibiotic prophylaxis in urological procedures in patients with asymptomatic bacteriuria, with the purpose of diminishing the bloodstream and of the surgical site infections. If it is scientifically demonstrated that those patients who receive a single dose of antibiotic on the same day of the procedure, have the same safety and effectiveness compared to the other two groups, would reduce hospital stay, surgical waiting time and indiscriminate use of antibiotics that generate multidrug-resistant microorganisms, thus generating an impact on Public Health and on the quality of care.