Multidrug-Resistant Gram-Negative Urinary Tract Infections (UTIs) Increase the Risk of Rejection, CMV Viremia, and Graft Loss After Kidney Transplantation

Background: Multidrug-resistant (MDR) Gram-negative UTIs caused by extended-spectrum β-lactamases (ESBL) and carbapenem-resistant Enterobacteriaceae (CRE) are increasingly common in kidney transplant recipients (KTR), yet their clinical consequences relative to other Gram-negative infections remain unclear. Methods: In this single-center study from a high-endemic area, we retrospectively evaluated the impact of MDR colonization (Colonization), MDR Gram-negative infection (MDR Infection), presumptive MDR infection (i.e., no isolates available; Presump. MDR), and non-MDR Gram-negative infection (non-MDR Inf.) on major post-transplant complications, including CMV and BKPyV viremia, acute rejection, donor-specific antibodies (DSA), graft function, and overall transplant failure. We used multivariable cause-specific hazard Cox regression models with time-varying covariates and random-coefficient mixed models. Results: Among 521 KTRs, distributed across overlapping conditions, 212 (40.7%) had MDR Colonization, 92 (17.7%) MDR Infection, 61 (11.7%) Presump. MDR, 67 (12.9%) non-MDR Inf., and 242 (46.4%) had no infection. Compared with No Infection group, only MDR infection was associated with a steeper decline in eGFR slope (_−5.50−2.91_−0.33 mL/min/1.73 m² per year; p = 0.027) and increased incidence of transplant failure (adjusted hazard, aHR, associated with history of MDR Infection = _1.76 4.11_9.61; p = 0.001. MDR infection history was also the only condition associated with CMV viremia (aHR = _1.051.83_3.18; p = 0.034), and with rejection (aHR = _1.031.69_2.76; p = 0.036), though it was not associated with BKPyV viremia or de novo DSA. Colonization, Presump. Inf., and non-MDR Inf. were not independently associated with complications or transplant failure. Conclusion: Documented MDR Gram-negative UTIs, but not colonization or non-MDR UTI, are independently associated with acute rejection, CMV viremia, and poorer kidney allograft outcomes.