Recurrent urinary tract infections (rUTIs) are a frequent clinical challenge, particularly in women, immunocompromised patients, and those with underlying urological or neurological conditions. Prolonged antibiotic prophylaxis is associated with adverse effects and rising antimicrobial resistance. This study aimed to evaluate the clinical effectiveness and economic impact of a sublingual bacterial autovaccine used as prophylaxis in patients with rUTIs, including high-risk subgroups.

This was a retrospective, observational, single-centre study. We included adult patients with rUTIs who had not received immunotherapy previously and were prescribed a sublingual bacterial autovaccine for 12 months. Data from the 12 months before and after treatment initiation were compared. Variables included: UTI episodes, primary and emergency care visits, hospital admissions, imaging, urine analyses, and antibiotic use. Patients with renal transplantation or neurogenic bladder were not excluded. Cost analysis was based on regional healthcare tariffs. Data were analysed descriptively and subgroup comparisons were conducted.

A total of 102 patients were included, among them 6 kidney transplant recipients and 13 with neurogenic bladder. After 12 months of immunotherapy, 97.02% of patients experienced a reduction in UTI frequency, with an overall decrease of 79.03% in infection episodes. Primary care and emergency visits decreased by 68.55% and 70.37%, respectively. Hospital admissions were also markedly reduced. A cost analysis showed a total annual saving of €154,210 (60.37% reduction).
A subgroup analysis revealed statistically significant reductions in transplant patients (mean UTIs: 7.6 vs 1.8; p=0.028), and an 83.9% decrease in neurogenic bladder patients (from 87 to 14 episodes). No admissions occurred in either subgroup during follow-up.

Sublingual bacterial immunotherapy appears effective in reducing the clinical and economic burden of rUTIs, including in high-risk populations. These findings support its use as a non-antibiotic preventive option in the context of growing antimicrobial resistance.

Bacterial immunotherapy may be a valuable tool in the prophylaxis of rUTIs. It offers clinical benefit, reduces healthcare costs, and shows promising results in complex populations such as transplant recipients and patients with neurogenic bladder.