Emergence of Extended-Spectrum β-Lactamase Urinary Tract Infections Among Hospitalized Emergency Department Patients in the United States

Ann Emerg Med. 2021 Jan;77(1):32-43. doi: 10.1016/j.annemergmed.2020.08.022. Epub 2020 Oct 31.


Study objective: Enterobacteriaceae resistant to ceftriaxone, mediated through extended-spectrum β-lactamases (ESBLs), commonly cause urinary tract infections worldwide, but have been less prevalent in North America. Current US rates are unknown. We determine Enterobacteriaceae antimicrobial resistance rates among US emergency department (ED) patients hospitalized for urinary tract infection.

Methods: We prospectively enrolled adults hospitalized for urinary tract infection from 11 geographically diverse university-affiliated hospital EDs during 2018 to 2019. Among participants with culture-confirmed infection, we evaluated prevalence of antimicrobial resistance, including that caused by ESBL-producing Enterobacteriaceae, resistance risk factors, and time to in vitro-active antibiotics.

Results: Of 527 total participants, 444 (84%) had cultures that grew Enterobacteriaceae; 89 of 435 participants (20.5%; 95% confidence interval 16.9% to 24.5%; 4.6% to 45.4% by site) whose isolates had confirmatory testing had bacteria that were ESBL producing. The overall prevalence of ESBL-producing Enterobacteriaceae infection among all participants with urinary tract infection was 17.2% (95% confidence interval 14.0% to 20.7%). ESBL-producing Enterobacteriaceae infection risk factors were hospital, long-term care, antibiotic exposure within 90 days, and a fluoroquinolone- or ceftriaxone-resistant isolate within 1 year. Enterobacteriaceae resistance rates for other antimicrobials were fluoroquinolone 32.3%, gentamicin 13.7%, amikacin 1.3%, and meropenem 0.3%. Ceftriaxone was the most common empirical antibiotic. In vitro-active antibiotics were not administered within 12 hours of presentation to 48 participants (53.9%) with ESBL-producing Enterobacteriaceae infection, including 17 (58.6%) with sepsis. Compared with other Enterobacteriaceae infections, ESBL infections were associated with longer time to in vitro-active treatment (17.3 versus 3.5 hours).

Conclusion: Among adults hospitalized for urinary tract infection in many US locations, ESBL-producing Enterobacteriaceae have emerged as a common cause of infection that is often not initially treated with an in vitro-active antibiotic.

Trial registration: ClinicalTrials.gov NCT03346603.

Publication types

  • Observational Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Anti-Bacterial Agents / therapeutic use
  • Emergency Service, Hospital / statistics & numerical data*
  • Enterobacteriaceae / drug effects
  • Enterobacteriaceae Infections / drug therapy
  • Enterobacteriaceae Infections / epidemiology
  • Female
  • Humans
  • Male
  • Middle Aged
  • Prospective Studies
  • Risk Factors
  • United States / epidemiology*
  • Urinary Tract Infections / drug therapy*
  • Urinary Tract Infections / epidemiology
  • Young Adult
  • beta-Lactam Resistance*


  • Anti-Bacterial Agents

Associated data

  • ClinicalTrials.gov/NCT03346603