Introduction: Rapid detection of extended-spectrum β-lactamases is essential. In this study, we evaluated the potential impact of β-lacta test on both the times to appropriate antibiotic therapy and to the implementation of patient isolation measures. Patients and methods: We included prospectively all the patients admitted to the emergency department for clinical suspicion of urinary tract infection. Compared with physician's decision, we analysed the potential impact of β-lacta test on the initial antibiotic therapy and on the implementation of hygiene measures. This study has been registered under number NCT02897609. Results: We included 203 patients, 43% with acute pyelonephritis and 21% with acute prostatitis. The β-lacta test had a 95.2% sensitivity and a 99.5% specificity to detect extended-spectrum β-lactamases. Taking the β-lacta test results into account would have decreased significantly both the times to appropriate therapy and to isolation measures from 54 to 2.7 h and from 55.2 to 2.6 h, respectively. Conclusion: The β-lacta test could reduce significantly the times to appropriate therapy and implementation of isolations measures