TOPLINE:

Older adults with urinary tract infections (UTIs) who used cotrimoxazole faced approximately double the risk of developing adverse events (AEs) compared with those who used fluoroquinolones. They also had more treatment discontinuations due to AEs.

METHODOLOGY:

• Researchers conducted a retrospective study across eight hospitals in France to assess the rates of AEs during treatment with fluoroquinolones vs cotrimoxazole in older men with UTIs treated with these drugs between 2019 and 2023.
• A total of 228 patients with UTIs (median age, 85 years) who required at least 7 days of inpatient monitoring during treatment were assessed; of these patients, 131 received fluoroquinolones and 97 received cotrimoxazole.
• The primary outcome was the occurrence of at least one AE during treatment, and the secondary outcome was the occurrence of an AE that led to treatment discontinuation.

TAKEAWAY:

• A significantly higher percentage of patients in the cotrimoxazole group than in the fluoroquinolone group experienced AEs (48.5% vs 29.7%; P = .006); cotrimoxazole was associated with a higher risk for AEs (adjusted odds ratio, 2.10; P = .01).
• Overall, 6.2% of patients discontinued treatment due to AEs; discontinuation was more common with cotrimoxazole than with fluoroquinolones (11.3% vs 2.3% of patients; P = .009).
• Acute kidney injury and metabolic disorders were the most frequent AEs and occurred more often in the cotrimoxazole group than in the fluoroquinolone group (P < .05 for both).

IN PRACTICE:

"Beyond efficacy, antibiotic selection should consider tolerability, microbiota impact, and resistance emergence, with an individualized balance for each patient. In older patients, especially the frailest and with multimorbidity, treatment tolerability is crucial to minimize drug-induced harm," the authors wrote.

SOURCE:

The study was led by C Gouraud, Centre Hospitalier Intercommunal de Villeneuve-Saint-Georges, Villeneuve-Saint-Georges, France. It was published online on May 11, 2026, in Open Forum Infectious Diseases.

LIMITATIONS:

This study was limited by its observational, retrospective design and small sample size, which may have limited the detailed comparison of AEs. Additionally, the inclusion of patients with high frailty and multiple comorbidities limited the generalizability of the findings and inherently increased the risk for AEs.

DISCLOSURES:

The study did not receive any external funding. The authors declared having no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.