Older Age, Prior AMR Risk Factors for Adverse Outcomes in Uncomplicated UTI

In women with uncomplicated urinary tract infections (UTI), the need for new antibiotic therapy was found to be more likely among those whose initial therapy did not cover the causative uropathogen. Women at increased risk for adverse outcomes included those who were older, those who were hospitalized, and those with previous antimicrobial resistance (AMR) or exposure. These study results were published in Open Forum Infectious Disease.

Data was collected from female outpatients with a positive urine culture with oral antibiotics. In this retrospective cohort study, data were collected between January 2015 and December 2019 from female outpatients aged 12 years and older who had positive urine cultures and had received oral antibiotic therapy ±1 day from the index culture. The researchers analyzed isolate susceptibility to initial antibiotic therapy, patient age, all-cause hospitalization, and history of antimicrobial resistance (AMR) and exposure within 12 months of the index culture for associations with adverse outcomes within a 28-day follow-up period. Assessed outcomes included dispensation of new antibiotics suggestive of empiric treatment failure, all-cause hospitalization, and all-cause outpatient emergency department (ED) or clinic visits. The researchers used generalized linear mixed models to evaluate the effect of uncomplicated UTI conferred by nonsusceptible isolates on patient outcomes.

A total of 2366 index uncomplicated UTI episodes with positive urine cultures were evaluated, representing 2087 women. The mean patient age was 48 (range, 12-90) years, and 80.6% and 19.4% of isolates in the UTI episodes evaluated were and were not susceptible to initial antibiotic therapy, respectively. Escherichia coli (78.5%) and Klebsiella pneumoniae (11.3%) were the most commonly isolated uropathogens.

Patients older than 50 years were significantly more likely to require new antibiotic treatment within 28 days of the index culture compared with those aged 12 to 17 years (odds ratio [OR], 1.7; 95% CI, 1.0-3.1; P <.0001). All-cause hospitalization also was significantly more likely in patients older than 50 years (OR, 10.0; 95% CI, 1.4-73.8; P =.0004).

Patients with isolates that were nonsusceptible to initial antibiotic treatment were 60% more likely to receive new antibiotic treatment within 28 days compared with those with susceptible isolates (29.0% vs 18.1%, respectively; OR, 1.6; 95% CI, 1.3-2.1, P =.0001). The presence of isolates that were nonsusceptible to nitrofurantoin within 90 days prior to the index culture also was significantly associated with the need for new antibiotic treatment (OR, 2.2; 95% CI, 1.3-4.0; P =.0195).

Further analysis was performed to assess factors significantly associated with all-cause outpatient ED or clinic visits. These included the presence of isolates that were nonsusceptible to fluoroquinolone within 90 days prior to the index culture (odds ratio [OR], 2.3; 95% CI, 1.2-4.5; P =.0406), and the dispensation of oral antibiotics within 90 days prior to the index culture (OR, 1.5; 95% CI, 1.1-1.9; P =.0130).

Study limitations include the potential presence of unmeasured confounders and the inability to confirm whether dispensed antibiotics were used as prescribed. In addition, the inclusion of only patients with positive urine cultures may have led to a higher percentage of patients with recurrent uncomplicated UTI in the overall population.

“This study found that approximately 1 in 5 uUTI [uncomplicated UTI] episodes were caused by isolates that were not susceptible to the initial antimicrobial prescribed,” the researchers noted. According to the researchers, “[T]hese data encourage physicians to consider patient-specific risk factors during initial clinical assessment, because this could help improve empiric treatment choices for uUTI…”

Disclosure: This research was supported by GSK. Please see the original reference for a full list of disclosures.