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Pivmecillinam proved highly effective in treating uUTIs, with trial reanalysis supporting its FDA approval after decades of European use.  

Researchers conducted a retrospective study published in June 2025 issue of Clinical Infectious Diseases to reanalyze data from earlier clinical trials using current Food and Drug Administration (FDA) efficacy criteria to support the approval of pivmecillinam for uncomplicated urinary tract infection (uUTI).  

They reviewed 14 studies and identified 3 randomized controlled trials (RCTs) that provided subject-level data on individuals with uUTI treated with 185 mg pivmecillinam 3 times daily for 3–7 days. Reanalysis focused on overall, clinical, and microbiological response rates in the microbiological intention-to-treat population (urine culture ≥10⁵ colony-forming units/mL; ≤2 microorganism species; no baseline pathogen resistant to comparator).  

The results showed that across the 3 primary studies, overall success with pivmecillinam at the test of cure (Days 7–15) ranged from 62.0% to 71.7%. Clinical success varied from 63.5% to 82.7%, and microbiological success ranged from 74.3% to 86.9%. Overall success was greater with pivmecillinam than with placebo ([95%CI  for the difference, 41.2–62.0]) or ibuprofen ([31.2–56.5]), and comparable to cephalexin ([−15.6 to 7.4]). Efficacy was observed in uUTIs caused by Enterobacterales, including Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae, and Staphylococcus saprophyticus.  

Investigators concluded that oral pivmecillinam demonstrated effective treatment outcomes for uncomplicated urinary tract infection and supported its recent regulatory approval in the United States. 

Source: academic.oup.com/cid/advance-article/doi/10.1093/cid/ciaf280/8174614