Introduction: The increasing prevalence of carbapenem-resistant Klebsiella pneumoniae (CR-Kp) limits effective treatment options. The aim of this study was to evaluate the susceptibility patterns of CR-Kp strains isolated from urine cultures to oral treatment options recommended by the Infectious Diseases Society of America guidelines, and ceftazidime-avibactam. Additionally, clinical data and outcomes of patients diagnosed with CR-Kp urinary tract infections (UTI) who were treated with fosfomycin sodium-including therapy regimens (FSITR) were analyzed.
Methodology: This retrospective cohort study included adult patients with urine culture-proven CR-Kp between March 2016 and October 2022. Demographic and clinical data, antibiotic susceptibility, treatment outcomes, and one-month mortality (OMM) were evaluated.
Results: A total of 179 patients were included. The susceptibility to fosfomycin tromethamol, nitrofurantoin, and co-trimoxazole (TMP-SMX) were (33.7%; 55/163), (7.7%; 13/167), and (11.1%; 20/179), respectively. All strains were resistant to ciprofloxacin. The susceptibility data compared until 2020 (pre-COVID-19) and afterwards, revealed TMP-SMX susceptibility (4.9% vs 24.1%, p = 0.0001) increased significantly. Susceptibility data for ceftazidime-avibactam were available for 22 isolates and 59% of the isolates were sensitive. OMM of the 179 patients with CR-Kp in urine cultures was 37.4% (67/179). There were 9 FSITR cases. Among those, microbiological eradication was achieved in 87.5% (7/8) and OMM was 44.4% (4/9).
Conclusions: Clinical experience may be feasible and needed to assess the efficacy of nitrofurantoin and TMP-SMX. Fosfomycin-including regimens may serve as a salvage treatment option for CR-Kp UTI in selected patients. However, the retrospective and single-center design of the study should be considered as a limitation.
Keywords: Enterobacteriaceae; antibiotherapy; carbapenem; resistance; urinary tract.
Copyright (c) 2026 Arda Kaya, Deniz Akyol-Seyhan, Seichan Chousein-Memetali, Melike Yaşar, Merve Mert-Vahabi, Dilşah Başkol-Elik, Şükrü Dirik, Gamze Şanlıdağ-İşbilen, Cansu Bulut-Avşar, Melike Demir-Görür, Gunel Guliyeva, Ayşe Uyan-Önal, Uğur Önal, Nazlıhan Yalçın, Buse Kenanoğlu, Şevket Yeniyol, Deniz Dağ, Pervin Korkmaz, Erkin Özgiray, Devrim Bozkurt, Hadiye Şirin, Ece Çınar, Kubilay Demirağ, Hilal Sipahi, Feriha Çilli, Şöhret Aydemir, Meltem Taşbakan, Hüseyin A Erdem, Hüsnü Pullukçu, Tansu Yamazhan, Sercan Ulusoy, Bilgin Arda, Oğuz R Sipahi.