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Volume 39, Issue 2

Original Article

Extended-Spectrum β-Lactamase Positivity and 10-Year Resistance Trends in Escherichia coli and Klebsiella pneumoniae Isolates Causing Community-Acquired Urinary Tract Infections

Dilem Dinç
Affiliations
  • Ondokuz Mayıs Üniversitesi, Tıp Fakültesi Öğrencisi, Samsun, Türkiye
https://orcid.org/0009-0008-7912-3201
,
Aslı İrem Seyfikli
Affiliations
  • Ondokuz Mayıs Üniversitesi, Tıp Fakültesi Öğrencisi, Samsun, Türkiye
https://orcid.org/0009-0002-4355-6976
,
Osman Furkan Gedik
Affiliations
  • Ondokuz Mayıs Üniversitesi, Tıp Fakültesi Öğrencisi, Samsun, Türkiye
https://orcid.org/0009-0001-5611-2090
,
Osman Furkan Gedik
Affiliations
  • Ondokuz Mayıs Üniversitesi, Tıp Fakültesi Öğrencisi, Samsun, Türkiye
https://orcid.org/0009-0001-5611-2090
,
Fatih Temoçin
Affiliations
  • Ondokuz Mayıs Üniversitesi, Klinik Mikrobiyoloji ve İnfeksiyon Hastalıkları Anabilim Dalı, Samsun, Türkiye
https://orcid.org/0000-0002-4819-8242
  • antibiotic resistance
  • community-acquired urinary tract infections
  • Escherichia coli
  • extended-spectrum β-lactamase
  • Klebsiella pneumoniae

Abstract

Objective: Community-acquired urinary tract infections (CA-UTIs) are common bacterial infections most frequently caused by Escherichia coli and Klebsiella pneumoniae. The present study evaluated extended-spectrum β-lactamase (ESBL) positivity rates, antibiotic resistance profiles, and 10-year trends in resistance among adult patients with CA-UTIs caused by E. coli and K. pneumoniae.

Methods: This retrospective study evaluated adult outpatients admitted to Ondokuz Mayıs University Medical Faculty Hospital between January 1, 2014, and December 31, 2023, whose urine cultures yielded ≥10⁵ colony-forming units (CFU)/mL of E. coli or K. pneumoniae. Antimicrobial susceptibility testing was performed using the VITEK® 2 Compact system (bioMérieux, Marcy l’Etoile, France), and the results were interpreted according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. ESBL positivity was defined according to the “presumed ESBL phenotype” approach described in the Clinical and Laboratory Standards Institute (CLSI) M100 guideline.

Results: A total of 5168 isolates were evaluated. Of the isolates, 83.5% (n=4316) were E. coli and 16.5% (n=852) were K. pneumoniae. The overall ESBL positivity rate was 28.9%. ESBL positivity was detected in 27% of E. coli isolates and 38.4% of K. pneumoniae isolates (p<0.001). A significant increase in the proportion of K. pneumoniae isolates was observed during the second 5-year study period (p<0.001). Resistance rates to ceftriaxone, ceftazidime, and second-generation cephalosporins were high in both pathogens. Ciprofloxacin resistance was 44.3% in E. coli isolates and 33.6% in K. pneumoniae isolates. Nitrofurantoin resistance was low in E. coli isolates (3.0%) but high in K. pneumoniae isolates (39.2%). In addition, carbapenem resistance in K. pneumoniae isolates increased markedly over the years.

Conclusion: Our study demonstrated that ESBL positivity and antimicrobial resistance rates among E. coli and K. pneumoniae isolates causing CA-UTIs increased over time. In particular, increases in ESBL positivity and carbapenem resistance among K. pneumoniae isolates are progressively limiting empirical treatment options. Therefore, regular reassessment of empirical treatment approaches based on current local resistance data is critical.

Keywords: Escherichia coli, Klebsiella pneumoniae, community-acquired urinary tract infections, extended-spectrum β-lactamase

  • 99–105
  • Dilem Dinç
  • [email protected]
  • 10.36519/kd.2026.5361
  • November 16, 2025
  • February 24, 2026
  • June 29, 2026
  • 13
  • 3
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  • This work is licensed under a Creative Commons Attribution-Non Commercial 4.0 International License. CC BY-NC
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