Background: Urinary tract infection (UTI) is the most common infection in the first two years after kidney transplant (KT). Understanding the incidence of recurrent UTI and the epidemiology of antimicrobial resistant (AMR) UTIs can inform both UTI management in KT recipients (KTRs) and approaches to transplant antimicrobial stewardship. 
Methods: Data was extracted from the electronic health record (Epic), for all KTRs from 2017 to April 2023, including all urine culture results for KTRs with antibiograms and antibiotics prescribed. UTIs were classified as AMR if resistant to quinolones, ceftriaxone or carbapenems (Gram negative organisms) or vancomycin (Gram positive organisms), and receipt of these antibiotics were classified as resistance-implicated antibiotics (RIAbx). Antibiotic duration was classified as short (≤4 days), medium (5-13 days) or prolonged (≥14 days). Survival analysis based on receipt of RIAbx used the date of KT as start date, date of first AMR UTI as end point, with data censored after 2 years. Crude logistic regression for KTRs with ≥1 UTI used duration of antibiotic as the variable and subsequent AMR UTI as the outcome. Statistical analysis was performed using SAS 9.4.
Results: 407 of 985 (41%) KTRs had at least one UTI after transplant, with the majority (98%) occurring >30 days post-transplant. Enterobacteriaceae accounted for 46% of UTIs. 61% of KTRs had ≥1 UTI recurrence within 6 months of the initial UTI and among these, 26% had AMR UTIs.  Among 324 KTRs with recurrent UTI whose initial UTI was not AMR UTI, 22% received RIAbx, with 7.5% receiving ≥14 days of RIAbx. Receipt of RIAbx was associated with a higher probability of subsequent AMR UTI. Of KTRs with at least one UTI, a prolonged antibiotic course was associated with subsequent AMR UTI, regardless of the resistance of the first UTI. Shorter courses of antibiotics were not associated with subsequent AMR UTI. Neither UTI nor AMR UTI was associated with an increase in CMV or BK viremia incidence or duration, and rates of UTI-associated bacteremia were low: 5.2% overall and 8.9% among KTRs with AMR UTI.
Conclusions: KTRs have a high burden of UTIs and AMR UTIs in the first 2 years post-transplant. Receipt of RIAbx and antibiotic courses ≥14 days were associated with higher probability of subsequent AMR UTI.