Early urinary tract infection after kidney transplantation: timing, stent association, extended-spectrum β-lactamase infections, and clinical outcomes in a large cohort.

Background: Urinary tract infection (UTI) including extended-spectrum β-lactamase (ESBL)-producing organisms is a common early complication after kidney transplantation. Increasing prevalence of ESBL may adversely affect graft and patient outcomes. This study aimed to evaluate the incidence, timing, predictors, and outcomes of UTI, including ESBL infection, after kidney transplantation. Materials and methods: We retrospectively studied 1,804 adult kidney transplant recipients (2016-2024) at a tertiary center. UTIs were analyzed for incidence, timing, microbiology, and predictors using multivariable logistic regression. Outcomes included rejection, graft loss, and mortality. ESBL and non-ESBL UTIs were compared, and long-term outcomes assessed using Cox regression. Results: UTI occurred in 693 recipients (38.4%) within the first year post-transplant with 57.4% occurring within 30 days and 84.2% within 90 days. UTIs were more common during ureteric stent indwelling than after removal (64.3% vs. 35.7%). Independent predictors included female sex, older age, deceased donor transplantation, pre-transplant UTI, and post-transplant urological complications. ESBL UTI were identified in 47.9% of patients and were associated with earlier infection, higher recurrence rates and occurred more frequently during stent indwelling (69.0% vs. 60.1%, Conclusions: UTIs are common early after kidney transplantation, particularly during ureteric stent indwelling. ESBL infections are independently associated with adverse graft outcomes and mortality, supporting targeted surveillance, antimicrobial stewardship, and ureteric stent management optimization.