Community-Acquired Urinary Tract Infection: Adverse Effects of Cotrimoxazole vs Fluoroquinolones

Photo taken in Bangkok, Thailand
Investigators conducted a cohort study that compared adverse effects and outcomes among patients with community-acquired urinary tract infection treated with cotrimoxazole vs fluoroquinolones.

In patients with community-acquired urinary tract infection (cUTI) due to Enterobacteriaceae, treatment with cotrimoxazole (combination of trimethoprim and sulfamethoxazole) was associated with increased adverse effects (AE) and prolonged hospitalization compared with treatment with fluoroquinolones, according to study results published in Infectious Diseases Now.

With the increasing prevalence of multidrug-resistant bacteria, restrictions to the use of broad-spectrum antibiotics are needed. In 2008, a team of investigators in France developed an internal guideline for cUTI treatment in which they used cotrimoxazole as the prioritized documented antibiotic therapy for susceptible bacteria.

In a cohort study conducted between 2008 and 2019, the investigators compared AEs and outcomes among patients with cUTI treated with cotrimoxazole vs fluoroquinolones. The study combined 28 parameters for all patients, such as diagnosis, microbiologic data, antibiotic therapy, AE, length of hospitalization, and outcomes.

A total of 640 patients (51% women; mean age, 65 years) with cUTI due to Enterobacteriaceae were included in the study: 295 were treated with cotrimoxazole, and 345 were treated with fluoroquinolone. In terms of comorbid conditions, there were no differences between the treatment groups.

The most common bacteria collected in urine samples were Escherichia coli and Klebsiella spp, which were isolated from 82% and 11% of samples, respectively. In 67 cases (10.4%), strains were resistant to cotrimoxazole, and in 44 cases (7.3%), strains were resistant to fluoroquinolones; 23 strains were extended-spectrum β-lactamase-positive Enterobacteriaceae.

Of the 2 treatment groups, the empiric antibiotic treatment combining third-generation cephalosporins with an aminoglycoside was more common among patients in the cotrimoxazole group compared with those in the fluoroquinolones group (10.8% vs 5.8%, respectively; P =.019).

Of the 25 AEs reported, 17 were in the cotrimoxazole group, and 8 were in the fluoroquinolones group (P =.025). The most common AEs were altered kidney function (n=8) in the cotrimoxazole group and digestive intolerance (n=3) in the fluoroquinolone group. Among patients with a reported AE, there was a significant increase in length of hospitalization (P <.001). The relative increases in the length of hospitalization stay among patients in the cotrimoxazole and fluoroquinolones groups were 73.5% and 29.5%, respectively.

“Our study suggests that the fight against the emergence of multidrug-resistant bacteria can entail collateral damage, for both patients and the health care system,” the investigators wrote.

“As the demonstration of the effectiveness of this policy has yet to be established, and because [cotrimoxazole] was associated with more AEs and prolonged [length of hospitalization], further study is needed to determine the cost effectiveness of the antibiotic strategy we recommend,” the investigators concluded.


Michelangeli C, Courjon J, Curlier E, Roger PM. Cotrimoxazole for community-acquired urinary tract infections leads to more adverse effects than fluoroquinolones. Infect Dis Now. 2021;51(4):374-376. doi:10.1016/j.idnow.2020.11.003