Background: Symptomatic urinary tract infection (UTI) is a common complication after urodynamic study (UDS). While the role of antibiotic prophylaxis before UDS is controversial.

Objective: To compare the incidence rate of symptomatic UTI after UDS in patients with and without antibiotic prophylaxis.

Materials and Methods: We conducted a randomized, open-label, noninferiority controlled trial in adults with asymptomatic bacteriuria who were undergoing UDS. The participants were randomly assigned (1:1) to receive either gentamicin 5 mg/kg plus ampicillin 1-gram intravenous (IV) infusion 1 hour before UDS or no prophylaxis. The primary outcome was an incidence rate of symptomatic UTI within 48 hours after UDS. Secondary outcomes were adverse effects and microbiological clearance of urine at 48 hours after UDS. The study was terminated early after the first interim analysis due to safety concerns.

Results: 26 patients were enrolled, median age was 52 years (range, 25 to 75 years), 69.2% were male, and all had a neurogenic bladder as indication for UDS. Of these, 13 patients each were allocated to the antibiotic prophylaxis group and the non-antibiotic prophylaxis group. In the antibiotic prophylaxis group, 12/13 (92.3%) received gentamicin plus ampicillin and one received ceftriaxone. The incidence rate of symptomatic UTI after UDS was significantly higher in patients with no antibiotic prophylaxis (5/13; 38.5%) than those who received antibiotic prophylaxis (0%) (p=0.04). No adverse drug events were observed. The microbiological clearance in urine at 48 hours after UDS was significantly higher in patients who received antibiotic prophylaxis (8/11; 72.7%) compared to those without antibiotic prophylaxis (0/13; 0%) (p<0.001).

Conclusion: Antibiotic prophylaxis reduced the incidence of symptomatic UTI in patients with neurogenic bladder and asymptomatic bacteriuria who were undergoing UDS. A single-dose of antibiotics within an hour prior to UDS seems to be a proper option.