There are no guidelines regarding the use of antibiotic prophylaxis for intravesical Botulinum toxin (BoNT-A) treatment for women with detrusor overactivity, and studies investigating their role demonstrate conflicting or inconclusive results. 
The reported rate of urinary tract infection (UTI) following BoNt-A varies widely from 10-44% and the majority of these studies involve procedures with antibiotic prophylaxis.
Our aim was to investigate the rate of UTI following intravesical BoNT-A without antibiotic prophylaxis, and the correlation between preceding and post-treatment UTI. We hypothesised that the rate of post-procedure UTI without antibiotic prophylaxis would be no greater than the reported risk in other studies.

Retrospective cohort study of women undergoing outpatient intravesical BoNT-A for detrusor overactivity in a district general hospital between 2020 and 2023, identifying 107 treatment episodes. Patients were screened pre-procedure to exclude UTI via urine culture and the majority (86%) treated with 100 units BoNT-A. Patients were followed up by telephone consultation at 6 weeks post-treatment. Data was collected from electronic and paper medical records.

All women had overactive bladder symptoms with 96% women confirmed detrusor overactivity on urodynamics. 71% (60/84) were post-menopausal and 88% (74/84) parous. 
The overall risk of UTI was 7.5% (8/107) at 6 weeks and 23% (23/107) at 6 months, as denoted by a positive urine culture in symptomatic patients. 
The risk of UTI within 6 weeks of BoNT-A treatment was significantly lower in patients with no preceding UTI history (12 months prior to treatment) compared to patients who did have a previous history of UTI; 2.5% (2/79) and 21% (6/28) respectively (relative risk 8.4; 95% CI 1.81 - 39.5; p=0.006). 
The risk of UTI within 6 months of BoNT-A treatment treatment was 18.9% (15/79) for patient with no preceding UTI history and 28.6% (8/28) for those with a previous UTI history, but this did not carry statistical significance (relative risk 1.5; 95% CI 0.71 - 3.16; p=0.28).

The majority of women that developed UTI following intravesical BoNT-A treatment did so more than 6 weeks after administration, therefore the role of prophylactic antibiotics is limited. Intravesical BoNT-A treatment without antibiotic prophylaxis did not lead to a greater risk of developing UTI. Women who had a previous history of UTI were more likely to have post-BoNT-A UTI in the first 6 weeks following treatment.

Antibiotic prophylaxis is not necessary for intravesical BoNT-A treatment in patients who have been screened for infection by urine culture pre-procedure. 
Previous UTI is a risk factor for developing post-BoNT-A UTI.