The impact of chronic loop diuretic therapy on urinary microbiology and clinical outcomes in hospitalized older adults

Abstract

Urinary tract infections (UTIs) are common among hospitalized older adults and are closely linked to antibiotic exposure and antimicrobial resistance. Loop diuretics are widely prescribed in this population and substantially alter urine volume and composition. However, their potential influence on urinary pathogen patterns or antimicrobial resistance remains unclear. This study evaluated the relationship between chronic loop diuretic therapy, urinary microbiology, and clinical outcomes in hospitalized older adults with UTIs. Patients aged ≥ 65 years who were admitted to acute geriatric wards between 2019 and 2024 with a working diagnosis of UTI and a positive urine culture were included. Patients treated with chronic loop diuretics prior to admission were compared with a control group without loop diuretic therapy (200 per group). Clinical, laboratory, microbiological, and geriatric characteristics were collected. Outcomes included urinary pathogen distribution, rates of third-generation cephalosporin-resistant Enterobacterales (3GCRE) and multidrug-resistant (MDR) isolates, length of stay, and mortality. Overall, 111 patients (27.8%) had a 3GCRE-positive index urine culture, and 164 (41.0%) had an MDR-positive index urine culture. No significant differences were observed between patients receiving chronic loop diuretics and controls in urinary pathogen distribution, antimicrobial resistance patterns, length of stay, or mortality. In adjusted analyses, chronic loop diuretic use was not associated with MDR isolation (aOR 1.07, 95% CI 0.67–1.70) or 3GCRE isolation (aOR 0.93, 95% CI 0.56–1.54). In secondary analyses, higher frailty and poorer functional status were associated with mortality. Among hospitalized older adults with UTI, chronic loop diuretic therapy was not associated with urinary pathogen distribution, MDR or 3GCRE isolation, length of stay, or mortality. Accordingly, loop diuretic use alone should not be used to infer a higher likelihood of resistant urinary pathogens or to justify broader empirical antimicrobial coverage.