Cotrimoxazole Linked to Higher Adverse Event Risk in Older Adults With UTIs: Study

A new study published in the journal of Open Forum Infectious Disease showed that compared to fluoroquinolones, cotrimoxazole was linked to around double the incidence of adverse events in older persons receiving treatment for urinary tract infections (UTIs).

Older men are particularly susceptible to urinary tract infections, which frequently manifest as unusual symptoms like delirium rather than regular fever or general urine problems. Clinical diagnosis is difficult because of this intricacy and the prevalence of persistent urine colonizations. Moreover, treatment failure and serious consequences, such as sepsis, are clearly more common in older men.

According to current medical standards, the main therapies for male patients should be cotrimoxazole or fluoroquinolones. Nevertheless, there are no particular modifications made to these standards for the elderly population. Due to changes in body composition and renal dysfunction, aging significantly modifies pharmacokinetics and pharmacodynamics. Frequent polypharmacy also greatly raises the risk of adverse outcomes and medication interactions. Careful antibiotic selection is still vital to balance effectiveness and toxicity because there is a dearth of studies evaluating the safety profiles of various therapies in this susceptible group. Therefore, the purpose of this study is to comprehensively assess and compare adverse occurrences among older men over 75 who are hospitalized.

Patients aged ≥75 who were treated with oral fluoroquinolone or cotrimoxazole for UTIs in 8 hospitals were included in this multicenter retrospective analysis. Hospitalization-related adverse events (AEs) were compared. Of the 228 patients (median age, 85 years), 97 (42.6%) received cotrimoxazole and 131 (57.4%) received fluoroquinolones.

The baseline traits were comparable. AEs occurred in 29.7% of patients treated with fluoroquinolones compared to 48.5% treated with cotrimoxazole (P =.006), and 2.3% vs. 11.3% (P =.009) resulted in treatment discontinuation. Metabolic problems were seen in 7.6% vs. 18.6% (P =.023) and acute renal damage in 7.2% vs. 29.4% (P <.001).

There was no discernible difference between mortality and other AEs. A twofold increased incidence of adverse events was linked to cotrimoxazole (adjusted odds ratio, 2.10; 95% CI, 1.18–3.74; P =.01). Overall, the results of this study suggest the use of FQs instead of CTM to reduce antibiotic-related adverse events in older men with UTIs. Harmonizing the classification of UTIm with the emergence of the concept of male cystitis may be of interest in order to reduce drug toxicity. 

Source:

Gouraud, C., Putot, A., Fraisse, T., Bermejo, M., Viala, B., Golstein, C., Lemarie, N., Roubaud Baudron, C., & Caraux-Paz, P. (2026). Safety of fluoroquinolones and cotrimoxazole in urinary tract infections in older males. Open Forum Infectious Diseases, 13(5), ofag271. https://doi.org/10.1093/ofid/ofag271