The Natural History and Impact of Urinary Tract Infections in Kidney Transplant Recipients

Abstract Background Urinary tract infections (UTIs) are the most common infection following kidney transplantation. However, the natural history of UTIs is incompletely understood, as is the impact of UTIs on patient outcomes. Methods A single-centre cohort study of kidney-only transplant recipients at the West of Scotland Renal Transplant Unit, UK was undertaken. A standardised protocol for UTI screening and treatment was followed. Patients were categorised into three groups based on the number of culture-proven UTI: no UTIs, 1–2 UTIs and ≥ 3 UTIs. Proportional odds logistic regression was performed to identify risk factors for developing UTIs, with adjustment for age, sex, primary renal diagnosis, donor type and induction immunosuppression. Results Of 1412 recipients, 1169 (82.8%) had no UTIs, 180 (12.7%) had 1–2, and 63 (4.5%) had ≥ 3. Key risk factors for ≥ 3 UTIs were female sex (adjusted odds ratio aOR 1.48, 1.15–1.91), older age (aOR 1.01, 1.00-1.02) and ATG induction (aOR 3.73, 2.16–6.45). Recipients whose kidney failure had been caused by lower urinary tract disorders were at increased risk of developing one or more UTIs (adjusted hazard ratio 1.86 1.03–3.34). Recipients with ≥ 3 UTIs had a lower estimated glomerular filtration rate (eGFR) at two years post-transplant (49.7 vs. 59.2 mL/min/1.73m², p = 0.03), but there was no significant difference is patient or graft survival at two years. Conclusions We report a relatively low rate of treated UTIs in the first two years post-kidney transplantation, with female sex, older age, and ATG induction identified as key risk factors. While UTIs did not increase graft loss or mortality, recurrent infections were associated with lower eGFR at two years. Targeted screening and prevention strategies should be considered for identified high-risk recipients.