The benefits and harms of antibiotic prophylaxis for urinary tract infection in older adults

Background — The role of antibiotics in preventing urinary tract infection (UTI) in older adults is unknown. We sought to quantify the benefits and risks of antibiotic prophylaxis among older adults.

Methods — We conducted a matched cohort study comparing older adults (≥66 years) receiving antibiotic prophylaxis, defined as antibiotic treatment for at least 30 days starting within 30 days of a positive culture, to patients with positive urine cultures that received antibiotic treatment but did not receive prophylaxis. We matched each prophylaxis recipient to 10 non-recipients based on organism, number of positive cultures, and propensity score. Outcomes included 1) emergency department (ED) visit or hospitalization for UTI, sepsis, or bloodstream infection within 1 year; 2) acquisition of antibiotic resistance in urinary tract pathogens; 3) antibiotic-related complications.

Results — Overall 4.7% (151/3,190) of UTI prophylaxis patients and 3.6% (n=1,092/30,542) controls required an ED visit or hospitalization for UTI, sepsis, or bloodstream infection (Hazard Ratio (HR) 1.33, 95%CI 1.12 to 1.57). Acquisition of antibiotic resistance to any urinary antibiotic (HR 1.31, 95%CI 1.18 to 1.44) and to the specific prophylaxis agent (HR 2.01, 95% CI 1.80 to 2.24) were higher in patients receiving prophylaxis. While the overall risk of antibiotic-related complications was similar between groups (HR 1.08, 95%CI 0.94 to 1.22) the risk of C. difficile and general medication adverse events was higher in prophylaxis recipients (HR 1.56, 95%CI 1.05 to 2.23; HR 1.62, 95%CI 1.11 to 2.29, respectively).

Conclusions — Among older adults with UTI, the harms of long-term antibiotic prophylaxis may outweigh their benefits.