#1654 Infectious complications after kidney transplantation: a retrospective study
Authors: Simões Pilar , Domingos Ana Sofia , Martins João Figueiredo , Da Costa Bernardo Do Sacramento Marques , Vieira Miguel Bigotte , Aires Ines , Ferreira Manuel Anibal A , Jorge Cristina 
Published: May 2024

Abstract

Background and Aims
Infection is a major cause of morbidity among kidney transplant recipients. Allograft rejection is a frequent cause of dysfunction and its treatment increases the risk for both common and opportunistic infections. Nevertheless, its exact impact on infection incidence and further worsening of allograft dysfunction is not fully known.
We aimed to characterize the incidence, nature, and severity of infectious complications following kidney transplantation, their association with previous rejection and its impact on allograft function.

Method
This was a single center retrospective study covering all patients transplanted between July 2021 and June 2023 in a tertiary referral center. Demographic and clinical data were collected from patient records, including donor and patient features, graft function over time and occurrence of either infection or rejection. Logistic regressions were adjusted considering sex, age, blood type and presence of diabetes as independent variables.

Results
A total of 139 patients were considered, 49 (35.3%) were women and 90 (64.7%) were men. Mean age was 49.6 ± 13.0 years. Median follow-up time was 375 [194-596] days. The main cause of renal disease was diabetes (37 patients, 26.8%) and most patients (113; 81.9%) were on hemodialysis for a median vintage of 3 [2.3] years.
Considering the 139 transplants performed, 113 (81.2%) were isolated kidney, 24 (17.4%) were simultaneous kidney-pancreas and 2 (1.4%) were simultaneous kidney-liver transplantation. Eleven (7.9%) were living donor. During follow-up time, in-hospital infection occurred in 34 (24.4%) patients, mostly urinary (13, 38%) and blood stream (11, 32%) infections. These events significantly delayed hospital discharge (15.88 ± 8.52 vs 26.05 ± 14.3 days, p-value=0.001).
During the follow up, a total of 107 (77%) patients developed 220 infection episodes leading to 47 hospital admissions. Urinary infections (64, 28.8%) and cytomegalovirus (CMV) viremia (64, 28.8%) were the most common at median follow-up time of 85.5 [40.25-183.75] and 159 [43.25-258.5] days, respectively. Median timing of diagnosis was 400.8 [203-614] days after transplant. They were much more common during the first three months (0.014 vs 0.002 per follow-up day). There were no differences in infection incidence between type of donor (p=0.76), type of allograft (p=0.361), immunosuppression protocol (thymoglobulin or basiliximab, p=0.45), renal replacement therapy or presence of diabetes. Regarding urinary infections, days of urinary catheterization (p=0.905), need for catheter replacement (p=0.092) or presence of residual diuresis (p=0.375) had no impact on infection rates. A positive correlation was found, between the number of infection episodes and creatinine increase over the first year (r=0.386; p&lt;0.000).
Allograft rejection was diagnosed and treated through protocol biopsy in 25 (18%) cases. These patients presented 17 confirmed episodes of infection over the three following months. Nine of them (36%) were CMV detectable viremias. Patients with a history of rejection had significantly more infections (1.49 ± 1.22 vs 2.20 ± 1.26, p=0.01), even after adjustment (p=0.006).

Conclusion
Early infections after kidney transplantation negatively impact hospital length of stay and allograft function. Furthermore, immunosuppressive treatment of allograft rejection carries a higher risk of infection. Further research is needed to clarify the impact of specific subsets of allograft rejection and immunosuppression protocols on the incidence of various types of infectious complications which could impair short-term renal function.