Antibiotic duration and breakthrough UTI outcomes in a retrospective cohort of recurrent UTI patients

Objectives: To evaluate whether guideline-consistent minimum durations of first-line antibiotics (minimum antibiotics) are non-inferior to antibiotic durations exceeding recommended minimums (non-minimum antibiotics) in preventing acute UTI persistence, relapse, and recurrence. Secondary objectives included identifying factors associated with UTI persistence, relapse and recurrence in a recurrent UTI cohort.

Methods: Retrospective review of culture-proven acute UTI episodes amongst female patients followed for recurrent UTIs from January 2016- December 2020. Acute UTI episodes were excluded if the patient had a prescription for a therapeutic antibiotic in the 4 weeks preceding the urine culture, if the UTI was treated with a non-first-line antibiotic, or if the patient had a history of neurogenic bladder, bladder foreign body, and/or post-void residual >300 ml on >2 occasions. Each acute UTI was categorized as treated with a minimum or non-minimum antibiotic duration (per AUGS Best-Practice Statement).¹ Then, the outcome of each UTI was recorded as persistent/relapse (same pathogen requiring additional antibiotics within 4 weeks of treatment), recurrent UTI (different pathogen requiring additional antibiotics within 4 weeks of treatment) or resolved (no additional cultures or antibiotics within 4 weeks of treatment). Clinical information was extracted from the medical record. The sample size was estimated to be 396 patients under a 10% noninferiority hypothesis for two proportions for UTI persistence/relapse and recurrence (α 0.05, β 0.20, 1:1 treatment ratio, average of 1 culture per patient). An interim analysis performed at 245 patients revealed an average of 1.6 eligible cultures per patient, and the sample size had been met.

Results: Two-hundred forty-five women with mean age 68.75+16.73 years and mean BMI 29.73+7.53 had a total of 553 acute UTIs meeting inclusion criteria. Two-hundred sixty (260/553, 47%) were treated with minimum antibiotics. Overall, 86/553 (15.6%) UTIs persisted or relapsed, 438/553 (79.2%) resolved, and 29/553 (5.2%) recurred, with no differences between patients who were prescribed minimum versus non-minimum antibiotics (all p >0.05). The primary outcome of difference in the proportions of UTIs with persistence/relapse or recurrence excluded the 10% non-inferiority margin (Table 1). There was no difference in the proportion of UTIs that resolved between groups (-4.0%, 95% CI -10.8%-2.8%, p=0.25), nor differences in UTI-related hospital admissions or pyelonephritis (both p >0.05). Pelvic Organ Prolapse Quantification System Ba measurements, steroid, and insulin use were not associated with increased odds of UTI persistence/relapse or recurrence. However, BMI >30 was associated with increased odds of persistence/relapse (OR 2.04, 95% CI 1.21-3.43, p=0.007).

Conclusions: In this cohort, antibiotic treatment durations in accordance with minimum recommended guidelines were non-inferior to those exceeding minimum guidelines in preventing acute UTI persistence/relapse and recurrence.

(1)Brubaker L, Carberry C, Nardos R, Carter-Brooks C, Lowder JL. American Urogynecologic Society Best-Practice Statement: Recurrent Urinary Tract Infection in Adult Women. Female Pelvic Med Reconstr Surg. 2018 Sep/Oct;24(5):321-335.