Etiology, incidence and clinical manifestations of urinary tract infections in evolving population of kidney transplant recipients – a single center 10-year retrospective analysis

Background The aim of the study was to verify how the kidney transplant (KTx) recipient profile changed between 2013 and 2022 and whether these changes influence the incidence, clinical manifestations, and microbiology of urinary tract infections (UTIs). Material and methods We analyzed clinical data and urine cultures collected during the first posttransplant year in patients who underwent KTx between January 2013 and December 2022. Results We studied data from 491 patients, who developed 448 episodes of UTIs, including asymptomatic bacteriuria (n=211, 47%), lower UTIs (n=80, 18%), acute graft pyelonephritis (n=97, 22%) and urosepsis (n=60, 13%). During two 5-year time periods (2013–2017 and 2018-2022), the number of recipients aged 70 years or over and 75 years or over increased (p=0.07). Recipients receiving a transplant more recently had higher numbers of mismatching HLA (p=0.001) and maximum CDC-PRA (p=0.001). As a result, in 2018–2022 KTx recipients were more likely to receive induction therapy vs. no induction and tacrolimus vs. cyclosporine-based maintenance immunosuppression (p<0.001). There was a parallel change in the etiology of UTIs, from Escherichia coli being the predominant pathogen (responsible for almost 35% of all UTI episodes in 2013-2017) to Klebsiella pneumoniae , which was isolated in 45% of all UTI episodes between 2018-2022. Klebsiella pneumoniae increased over calendar time (OR/year 1.23, 95% CI 1.08–1.39; p=0.0018). The proportion of highly resistant strains rose from 40.1% in 2013-2017, to 53.4% between 2018-2022 (p=0.008) and also increased in the linear model (p = 0.0369). Conclusion Over the 10-year period, there was a noticeable change in both KTx recipient and uropathogen characteristics, which requires alteration of antimicrobial prophylaxis and treatment strategies.