Urinary Tract Infection Prophylaxis Among Older Adults Increase Risks

Study authors examined 186,589 patients with an initial positive urine culture and receiving antibiotics to quantify risks and benefits of UTI prophylaxis in older adults.

Long-term antibiotic urinary tract infection (UTI) prophylaxis is associated with an increased risk of antibiotic resistance, hospitalization or emergency department visits, bloodstream infection, and sepsis among older adults aged 66 years or older, according to a retrospective cohort study published in Clinical Infectious Diseases.

Investigators considered patients to be on UTI prophylaxis if they received any antibiotic, except doxycycline, for 30 days or longer, which was initiated within the 30-day period following a positive urine culture. Study authors obtained data on 186,589 patients with an initial positive urine culture and receiving antibiotics through ICES, formerly known as the Institute for Clinical Evaluative Sciences. Among these patients, 3198 (1.0%) received antibiotic prophylaxis with a median antibiotic duration of 49 days (interquartile range, 30-94 days). Patients receiving prophylaxis were more likely to be men, live in a community setting, and have increased incidence of both hospital visits and positive urine cultures.

The most common antibiotic prophylactic agents used were nitrofurantoin (n=1401; 44.0%), trimethoprim/sulfamethoxazole (n=542; 17.0%), ciprofloxacin (n=500; 15.7%), cephalexin (5.9%), and trimethoprim (4.8%).

The primary efficacy outcome was as a composite of emergency department visit or hospitalization for UTI, bloodstream infection, or sepsis within 30 days to 1 year following a positive culture. The sensitivity analysis conducted, which limited prophylaxis agents to those most likely indicated for UTI, revealed that the risk of these outcomes continually occurred in patients (hazard ratio [HR], 1.29; 95% CI, 1.06-1.54).

Investigators also indicated the primary harm outcome was the detection of a repeat urinary isolate resistant to any antibiotic to which the first culture was susceptible.

A total of 431 prophylaxis recipients (20.9%) and 3218 patients in the control group (16.4%) developed resistance to any agent (HR, 1.31; 95% CI, 1.18-1.44). Additionally, antibiotic-associated harm appeared in 243 prophylaxis recipients (7.6%) and 2169 patients in the control group (7.1%; HR, 1.08; 95% CI, 0.94-1.22), including Clostridioides difficile infection (HR, 1.56; 95% CI, 1.05-2.23) and general agent-related adverse events (HR, 1.62; 95% CI, 1.11-2.29). The sensitivity analysis showed continual development of resistance to agents in patients (HR, 1.31; 95% CI, 1.17-1.45).

This study found no clinical benefit of antibiotic prophylaxis for UTI among older adults; however, it demonstrated the increased risk of harm associated with prophylaxis, most notably the development of antibiotic resistance. Limitations included the inability to distinguish true UTI infection from asymptomatic bacteriuria in the laboratory and administrative data collected.

“Our findings may help to highlight some of the risks of UTI prophylaxis in older adults which could shift clinician’s understanding of the ratio between benefits and harms in this population,” study authors concluded.


Langford BJ, Brown KA, Diong C, et al. The benefits and harms of antibiotic prophylaxis for urinary tract infection in older adults. Clin Infect Dis. Published online February 17, 2021. doi:10.1093/cid/ciab116