Complications In Kidney Transplant Recipients Research Articles

Myosteatosis as a New Risk Factor of Surgical Complications in Kidney Transplant Recipients: A Retrospective Study.

Computed tomography (CT) scan-defined myosteatosis is a common feature in ESKD patients receiving kidney transplantation (KT) and is associated with mortality after KT. We aimed to explore the impact of myosteatosis and other CT scan based morphometric data on the occurrence of early surgical complications after KT. We retrospectively measured on an unenhanced cross-sectional CT scan taken at the middle of the third lumbar vertebra performed within the previous year or at the time of KT: surface muscle index (total lumbar cross-sectional muscle area [CSMA] divided by height squared), subcutaneaous adipose tissue index, visceral adipose tissue index and muscle density (MD: mean CT attenuation of CSMA). Vessel to skin distance was the distance between iliac vein and skin. Myosteatosis was defined as MD below age- and sex-specific normal values. Logistic regression models were constructed to identify predictive factor of 90 days postoperative surgical complications with Clavien-Dindo score greater than or equal to 2, CD ≥ 2). Among the N = 200 patients, 61.5% were male with a mean age of 54.8 (± 13.8) years and a mean BMI of 25.1 (± 4.4) kg/m2. Sixty patients (30%) developed at least one postoperative complication (CD ≥ 2) in the first 3 months after KT. In two different multivariate analyses, MD (aOR: 0.95 for one Hounsfield unit increase, 95% CI: 0.91-0.99, p = 0.028) and myosteatosis status (aOR: 4.64, 95% CI: 2.18-9.90, p < 0.0001) were the only independent risk factors for postsurgical complication. Myosteatosis is independently associated with the occurrence of CD ≥ 2 postoperative complication within 90 days of surgery.

Unilateral Weakness Caused By Spinal Cord Infarction in a Renal Transplant Recipient.

Spinal cord infarction has various clinical presentations, depending on the vascular territory involved at the spinal cord level. The most common symptom is bilateral weakness. However, unilateral hemiparesis can occur if the sulcal artery is involved. Stroke is the most common and serious cerebrovascular complication associated with kidney transplantation. Clinically asymptomatic renal transplant recipients may experience increased intima-media thickening, which is significantly associated with an increased prevalence of cerebrovascular diseases. Herein, we report the case of a 64-year-old adult male with a history of kidney transplantation who presented with sudden-onset right-sided hemiparesis. The patient presented with right shoulder pain, right fingertip paresthesia, and recent dysuria, necessitating catheterization. T2-weighted magnetic resonance imaging at the C2-C3 level revealed hyperintensity corresponding to the right sulcal artery. Diffusion-weighted imaging revealed hyperintensities corresponding to T2 signal abnormalities, with a decreased apparent diffusion coefficient. The patient was diagnosed with cervical spinal cord infarction involving the right sulcal artery at the C2-C3 level. Subsequently, pulsed intravenous methylprednisolone and dual antiplatelet treatment (aspirin and clopidogrel) were administered. The patient showed a rapid and marked improvement in neurological function within 3 days. The patient in this case report initially presented with unilateral hemiparesis. The symptoms mimicked those of stroke, making accurate diagnosis challenging. This case highlights the need to consider spinal cord infarction in the differential diagnosis of patients presenting with unilateral hemiparesis. In addition, our findings suggest that spinal cord infarction may be a long-term complication in kidney transplant recipients.

Pre-transplant tacrolimus fluctuations predict BK virus infection risk in kidney transplants.

BK virus (BKV) infection is a significant complication in kidney transplant recipients, potentially leading to graft loss. The relationship between pre-transplant tacrolimus (TAC) pharmacokinetics and BKV infection risk remains unclear. This study aimed to investigate whether pre-transplant TAC blood concentration fluctuations are associated with BKV infection risk. We conducted a retrospective study of 135 living donor kidney transplant recipients at Hirosaki University between 2006 and March 2024. Patients were divided into BKV-infected (BKV) and non-infected (non-BKV) groups. TAC blood concentrations were measured at 4 points, including 0 h (2 h before TAC administration), 4, 6, and 12 h on the day before transplantation. Changes in TAC concentration from baseline (0h) were calculated for each time point. The concentration/dose (C0/D) ratio was used as an indicator of TAC metabolism rate. During a median follow-up of 54months, 29 recipients developed BKV infection. The BKV group had significantly older donors and showed a significantly larger decrease in TAC concentration at 12h compared to the non-BKV group (-1.5 vs. 0ng/mL, P = 0.008). There was no significant difference in pre-transplant C0/D ratios between the two groups. A decrease of ≥ 1.5ng/mL at 12h was identified as a significant risk factor for BKV infection (hazard ratio: 2.44, 95% confidence interval: 1.11-5.32, P = 0.026) in a propensity score-based inverse probability of treatment weighting multivariate Cox proportional hazards analysis. Pre-transplant TAC blood concentration fluctuations, particularly a large decrease at 12h from baseline, may be associated with increased BKV infection risk.

Frequency of BK virus genotypes in patients with colorectal cancer.

BK polyomavirus infection is prevalent and primarily asymptomatic, except for complications in kidney transplant recipients. Furthermore, its involvement in a tumorigenic family necessitates consideration in various malignancies such as urogenital tumors, prostate cancer, colorectal cancer (CRC), and brain cancer. This investigation encompassed 50 specimens of colorectal adenocarcinoma tumors, 50 adjacent tissues, and 40 urine samples, with patients having a mean age of 61 years ± 12.4 years. The detection of BK virus DNA VP1 gene and genotyping were carried out through nested-PCR and sequencing techniques. Through the utilization of nested-PCR, BK virus DNA was identified in 15/50 (30%) colorectal tumor samples and 3/50 (6%) adjacent tissues (p-value = 0.008). Additionally, 6/40 (15%) urine samples exhibited positive results for BK virus DNA. Notably, among these findings, 9/15 BK virus positive tumor tissues (60%) and 3/6 BK virus positive urine samples (50%) were confirmed to be positive for BK virus subtype 4 (p-value < 0.001), whereas 2 tumor samples and 3 urine samples were attributed to BK virus type 1b2. It is imperative to enhance one's understanding of the etiological and risk factors pertaining to cancers. The present findings offer substantiation of a potential correlation between BK virus infection and colorectal cancer. BK virus genotype 4 was found to be dominant among the CRC patients in this study.

P-1033. Post-transplant Outcomes in Kidney Transplant Recipients with Invasive Fungal Infections Prior vs. After the Emergence of SARS-CoV2

Abstract Background Invasive fungal infections (IFIs) are a serious complication in kidney transplant recipients (KTRs), leading to increased mortality and graft failure. Given changes in care associated with pandemic conditions and potential compounding effects of COVID-19 infection, we sought to determine whether the emergence of SARS-CoV2 contributed to a rise in adverse transplant outcomes associated with IFIs. Methods We performed a retrospective study of adult KTRs transplanted at Johns Hopkins from 2012-2018 with follow up through 5/2023. IFI diagnoses were based on EORTC/MSGERC criteria. If a patient had more than one IFI, the date of first IFI served as the index exposure. KTRs with and without IFIs were matched 1:1 on time-post-KT. We followed patients until all-cause graft loss (ACGL), a composite outcome of graft failure and mortality, and estimated cumulative incidence of ACGL prior vs. after emergence of SARS-CoV2 in 2/2020. We then determined whether the association between IFI and ACGL varied before vs during SARS-CoV2 pandemic using Cox regression with an interaction term and adjusting for age, transplant risk, and cardiovascular disease.Table 2.First post-transplant invasive fungal infection among kidney transplant recipients prior vs. post emergence of SARS-CoV2 Results Among 1453 KTRs, 79 (5.4%) had proven/probable IFIs of which 12 occurred after emergence of SARS-CoV2 (Table 1). Yeast caused the majority of IFIs (50/79) over the study period, but mold (5/12) and yeast (6/12) were equally represented among IFIs occurring after the emergence of SARS-CoV2 (Table 2). Prior to the pandemic, ACGL occurred in 66% (44/67) of KTRs with IFIs compared to 31% (414/1338) of KTRs without IFIs (log-rank p &amp;lt; 0.001). During the pandemic, ACGL occurred in 75% (9/12) of KTRs with IFIs compared to 31% of KTRs without IFIs (log-rank p &amp;lt; 0.001) (Fig 1). KTRs with IFIs had a 2-fold greater risk of ACGL (aHR 2.05, 95% CI 1.17-3.57, p = 0.012) prior to the pandemic and a 5.5-fold greater risk of ACGL (aHR 5.54, 95% CI 1.17-26.24, p &amp;lt; 0.01) during the pandemic. The risk of ACGL associated with IFIs was significantly different after the emergence of SARS-CoV2 (p-interaction term &amp;lt; 0.001; Fig 2).Figure 1.ACGL-free survival of KTR with IFIs vs. without IFIs Conclusion KTRs with IFIs had higher rates of ACGL during the pandemic, and molds constituted a greater proportion of the IFIs during the pandemic. The emergence of SARS-CoV2 seems to have shifted the epidemiology of IFIs among KTRs, leading to increased ACGL.Figure 2.ACGL-free survival of KTR with IFIs prior vs. after emergence of SARS-CoV2 Disclosures Nitipong Permpalung, MD, MPH, CareDx: Grant/Research Support|Cidara Therapeutics: Grant/Research Support|ClearView: Advisor/Consultant|IMMY Diagnostics: Grant/Research Support|Merck: Grant/Research Support|Pearl Diagnostics: Grant/Research Support|Pulmicide: Advisor/Consultant|Scynexis: Grant/Research Support

The aquaporin 5 promoter polymorphism and cytomegalovirus infection in kidney transplant recipients

Introduction: Cytomegalovirus (CMV) infection is a significant complication in kidney transplant recipients, impacting graft function and overall patient outcomes. Aquaporin 5 (AQP5) is a transmembrane channel that regulates renal function and impacts important mechanisms of immune cell migration and inflammation. Objectives: This research aimed to evaluate the impact of AQP5 polymorphism (-1364A/C) on the risk of CMV infection in kidney transplant recipients. Patients and Methods: One-hundred kidney transplant recipients were included in this study, divided into two groups; CMV+-positive (n=50) and CMV– -negative (n=50) patients. Additionally, a control group of 50 healthy individuals was included. The frequency of the AQP5 (-1364A/C) gene polymorphism was determined using the ARMS-PCR technique. Results: About 26% and 16% of patients in the CMV+ and CMV- groups experienced acute rejection after renal transplantation, respectively (P=0.220). The CC genotype of AQP5 (-1364A/C) polymorphism was present in 8% (n=4) of CMV+ and 4% (n=2) of CMV- recipients (4%); however, it was not observed in the control group (P=0.354). Conclusion: The results revealed that carrying at least one C-allele of the AQP5 1364A/C polymorphism (AC or CC genotypes) does not have a significant association with the incidence or presence of CMV infection in kidney transplant patients.

Infections in Kidney Transplant Recipients: Perspectives in French Caribbean.

Few studies have focused on the infectious complications in kidney transplant recipients in tropical regions, particularly in the Caribbean. The primary objective of this study was to determine the incidence of bacterial, fungal, and parasitic infections in kidney transplant recipients in the French Caribbean and French Guiana. We included all patients who received a kidney transplant at the University Hospital of Guadeloupe between January 2014 and October 2016, with post-transplant follow-up in the French Caribbean. A total of 91 patients were included, of whom 57 developed an infectious event during follow-up. When infections were documented (94/111), bacterial infections were the most frequent (79/94), followed by fungal (11/94) and parasitic infections (4/94). Four cases of nocardiosis were identified (4/79). Phaeohyphomycosis was the most common fungal infection (7/11). In a multivariate analysis, the female gender and diabetes mellitus at the time of transplant were significantly associated with a higher risk of infection. This study is the first to describe the epidemiology of infections in kidney transplant recipients in the Caribbean and to analyze the potential risk factors. We reported a similar profile of bacterial infections to that which were observed in the European and American studies. However, we found a higher incidence of tropical infections, such as nocardiosis and phaeohyphomycosis, which highlights the need for heightened awareness among healthcare teams to ensure earlier and more appropriate treatment. Further studies focusing on these rare tropical infections are necessary to better understand their risk factors.

Salmonella Aortitis in a Kidney Transplant Patient

Aortitis due to salmonella is a rare complication in kidney transplant recipients. In the general population, mortality among those with salmonella aortitis stands at 60%. We report a case of a kidney transplant recipient diagnosed with Salmonella aortitis affecting the bifurcation of the abdominal aorta. He underwent successful excision of the affected aorta with aortoiliac bifurcation graft replacement along with long-term antibiotic therapy.

Impact of Induction Agents on Torque Teno Viral Load and Year-1 Post-Transplant Complications in Kidney Transplant Recipients

Impact of Induction Agents on Torque Teno Viral Load and Year-1 Post-Transplant Complications in Kidney Transplant Recipients

Peritubular and Tubulointerstitial Inflammation as Predictors of Impaired Viral Clearance in Polyomavirus Nephropathy.

Introduction: Polyomavirus-associated nephropathy (BKPyVAN) is a common complication in kidney transplant recipients. The histological changes in the context of BKPyVAN and their association with the viral load and outcomes are still being investigated. Methods: This retrospective study involved 100 adult patients transplanted between 2000 and 2021, with available archived biopsy slides, aiming to analyze associations between viral load clearance in the blood (reduction in BKPyVAN-DNAemia below detection level) and histological features in biopsy-proven BKPyVAN. A kidney pathologist blinded to the clinical data reassessed the BANFF 2019 lesion scores in the BKPyVAN index biopsy. The primary endpoint was viral clearance three months after the diagnosis. Results: The presence of tubulointerstitial inflammation, peritubular capillaritis, and higher PVN Class at the diagnosis was linked to a reduced likelihood of viral clearance three months later (interstitial inflammation OR = 0.2, 95% CI [0.07-0.55], tubulitis OR = 0.39, 95% CI [0.21-0.73], peritubular capillaritis OR = 0.25, 95% CI [0.08-0.82], PVN Score OR = 0.1, 95% CI [0.03-0.4]), independently of other covariates. Combining the four lesions using the ROC analysis enhanced their capability to predict persistent BK viremia after 3 months with an AUC of 0.94. Conclusions: The presence of interstitial inflammation, tubulitis, and peritubular capillaritis, as well as the higher PVN Score, was associated with an up to 90% lower likelihood of viral load clearance three months post-diagnosis. These findings underscore the importance of histological evaluation as a surrogate of subsequent viral clearance and offer valuable insights for the management of BKPyVAN.

Early clearance of BK polyomavirus-DNAemia among kidney transplant recipients may lead to better graft survival.

BK polyomavirus (BKPyV)-DNAemia is a common complication in kidney transplant recipients (KTRs). The significance of achieving viral clearance at different time intervals is not well understood. All adult KTRs transplanted between January 1, 2015 and December 31, 2017 who developed BKPyV-DNAemia were included. Outcomes were analyzed based on persistent clearance of BKPyV-DNAemia at 3-month intervals up to 2 years after initial detection, and for recipients with persistent BKPyV-DNAemia at last follow-up. Uncensored graft failure, death-censored graft failure (DCGF), and a composite outcome of DCGF or fall in estimated glomerular filtration rate (eGFR) by ≥50% from the time of initial BKPyV-DNAemia were outcomes of interest. Of 224 KTRs with BKPyV-DNAemia, 58 recipients (26%) achieved viral clearance by 3 months after initial detection, 105 (47%) by 6 months, 120 (54%) by 9 months, 141 (63%) by 12 months, 155 (69%) by 15 months, 167 (75%) by 18 months, 180 (80%) by 21 months, and 193 (86%) by 24 months. Nine recipients (4%) had persistent BKPyV-DNAemia at last follow-up. Compared to recipients who achieved viral clearance by 3 months, those who achieved clearance by 6 months (adjusted odds ratio [aOR]: 3.15; 95% confidence interval [CI]: 1.22-8.12; p=.02) and 9 months (aOR: 3.69; 95% CI: 1.02-13.43; p=.04) had significantly increased risk for uncensored graft failure. There was no significant association between time to viral clearance and DCGF or composite outcomes. We found a trend of increased risk for uncensored graft failure among those who cleared BKPyV-DNAemia more slowly. Aiming to clear viremia early, without risking rejection, may be beneficial for allograft function and patient morbidity and mortality.

Incidence and Outcomes of BK Virus Nephropathy in Kidney Transplant Recipients With Steroid-Free Maintenance Immunosuppression

Incidence and Outcomes of BK Virus Nephropathy in Kidney Transplant Recipients With Steroid-Free Maintenance Immunosuppression

Toward an optimization of empirical antibiotic therapy in acute graft pyelonephritis: A retrospective multicenter study

Toward an optimization of empirical antibiotic therapy in acute graft pyelonephritis: A retrospective multicenter study

Association of T Cell Subsets and Platelet/Lymphocyte Ratio with Long-Term Complications in Kidney Transplant Recipients.

BACKGROUND Infection and chronic rejection remain major issues for kidney transplant recipients (KTRs). The present study aimed to explore the association of CD4+/CD8+ T cell ratio (CD4+/CD8+) and platelet/lymphocyte ratio (PLR) with long-term infection and chronic renal insufficiency in KTRs. MATERIAL AND METHODS KTRs admitted to a single hospital from June 2014 to December 2021 were divided into infected (164) and non-infected (107) groups based on clinical data. The levels of CD4+/CD8+, PLR, neutrophil/lymphocyte ratio (NLR), and C-reactive Protein (CRP) in KTRs with long-term infection, and their correlation with chronic kidney insufficiency, were analyzed. Survival analysis was used to evaluate the risk factors for long-term infection and chronic kidney insufficiency. RESULTS Spearman correlation analysis showed that chronic kidney insufficiency was positively correlated with PLR, and negatively correlated with CRP and CD4+/CD8+ (P<0.05). PLR was positively correlated with CRP, procalcitonin, erythrocyte sedimentation rate, and NLR, but negatively with CD4+/CD8+. CD4+/CD8+ was correlated with CRP, NLR, and PLR (P<0.05). Survival analysis and survival curves showed that PLR and CD4+/CD8+ were risk factors for long-term infection and chronic kidney insufficiency in KTRs (P<0.05). CONCLUSIONS CD4+/CD8+ and PLR were associated with long-term complications, and were risk factors for long-term infection and chronic kidney insufficiency in KTRs.

Standardized risk-stratified cardiac assessment and early posttransplant cardiovascular complications in kidney transplant recipients.

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in kidney transplant recipient (KTR). There is a dearth of standardized guidelines on optimal cardiovascular evaluation of transplant candidates. This single-center cohort study aims to determine the effectiveness of our standardized risk-stratified pretransplant cardiovascular screening protocol, which includes coronary angiography (CAG), in identifying advanced CVD, the proper pretransplant management of which could lead to a reduction in the incidence of major cardiac events (MACE) in the early posttransplant period. Out of the total 776 KTR transplanted between 2017 and 2019, CAG was performed on 541 patients (69.7%), of whom 22.4% were found to have obstructive coronary artery disease (CAD). Asymptomatic obstructive CAD was observed in 70.2% of cases. In 73.6% of cases, CAG findings resulted in myocardial revascularization. MACE occurred in 5.6% (N = 44) of the 23 KTR with pretransplant CVD and 21 without pretransplant CVD. KTR with posttransplant MACE occurrence had significantly worse kidney graft function at the first year posttransplant (p = 0.00048) and worse patient survival rates (p = 0.0063) during the 3-year follow-up period compared with KTR without MACE. After adjustment, the independent significant factors for MACE were arrhythmia (HR 2.511, p = 0.02, 95% CI 1.158-5.444), pretransplant history of acute myocardial infarction (HR 0.201, p = 0.046, 95% CI 0.042-0.970), and pretransplant myocardial revascularization (HR 0.225, p = 0.045, 95% CI 0.052-0.939). Asymptomatic CVD is largely prevalent in KTR. Posttransplant MACE has a negative effect on grafts and patient outcomes. Further research is needed to assess the benefits of pretransplant myocardial revascularization in asymptomatic kidney transplant candidates.

Risk factors and current state of therapy for anemia after kidney transplantation.

Post-transplant anemia is one of the most common complications in kidney transplant recipients, severely affecting patient prognosis and quality of life, and is an independent predictor of graft kidney loss and patient mortality. However, our clinical understanding and the attention given to post-transplant anemia are currently insufficient. This paper reviews the current status, risk factors, and therapeutic progress in anemia after transplantation in kidney transplant recipients. We recommend that clinical staff pay attention to anemia and its complications in kidney transplant recipients and intervene early for anemia.

Early surgical complications in kidney transplant recipients- A single center study

End-stage renal disease (ESRD) is becoming a significant global public health issue. The preferred course of treatment for people with ESRD is kidney transplantation, although its associated surgical complications raise serious doubts about the success rate of the procedure. Renal transplant surgical complications are frequently observed and can significantly affect graft performance, survival, and patient morbidity. This study aimed to analyze the frequency of early surgical complications, diagnoses, and treatment options in renal transplant patients. This retrospective cohort study included all transplanted patients with surgical complications from April 2017 to April 2022 at the Renal Transplant Unit of the Dow University of Health Sciences, Karachi, Pakistan. Out of 500 kidney transplant recipients, 86 patients (17.2%) experienced early post-transplant surgical complications. The most common complication was Lymphorrea (n=38, 7.6%) followed by wound infection (n=25 patients, 5%). The occurrence of these complications was associated with delayed graft function, indicating the need for careful monitoring and timely intervention in these cases. Future studies are needed to explore the predictors and risk factors of surgical complications in kidney transplantation and to identify strategies for reducing the incidence and improving the outcomes of these complications.

Interferon-alpha and MxA inhibit BK polyomavirus replication by interaction with polyomavirus large T antigen

IntroductionBK Polyomavirus (BKPyV) infection is a common complication in kidney transplant recipients and can result in poor outcomes and graft failure. Currently, there is no known effective antiviral agent. This study investigated the possible antiviral effects of Interferon alpha (IFNα) and its induced protein, MxA, against BKPyV. MethodsIn vitro cell culture experiments were conducted using human primary renal proximal tubular epithelial cells (HRPTECs). We also did animal studies using Balb/c mice with unilateral kidney ischemic reperfusion injury. ResultsOur results demonstrated that IFNα effectively inhibited BKPyV in vitro and murine polyomavirus in animal models. Additionally, IFNα and MxA were found to suppress BKPyV TAg and VP1 production. Silencing MxA attenuated the antiviral efficacy of IFNα. We observed that MxA interacted with BKPyV TAg, causing it to remain in the cytosol and preventing its nuclear translocation. To determine MxA's essential domain for its antiviral activities, different mutant MxA constructs were generated. The MxA mutant K83A retained its interaction with BKPyV TAg, and its antiviral effects were intact. The MxA T103A mutant, on the other hand, abolished GTPase activity, lost its protein-protein interaction with BKPyV TAg, and lost its antiviral effect. ConclusionIFNα and its downstream protein, MxA, have potent antiviral properties against BKPyV. Furthermore, our findings indicate that the interaction between MxA and BKVPyV TAg plays a crucial role in determining the anti-BKPyV effects of MxA.

Effects of an Educational Package on Quality of Life and Acute Complications in Kidney Transplant Recipients: A Clinical Trial

Background: Patients with chronic renal failure face many challenges in self-care after a kidney transplant. This treatment method affects their quality of life and leads to multiple complications. Objectives: This study aimed to evaluate the impact of an educational package on the quality of life (QoL) and complications of renal transplant recipients. Methods: This clinical trial was conducted on 72 patients (control and intervention groups) who had undergone kidney transplantation for the first time. The intervention involved an educational package comprised of five sessions. Besides, an educational booklet, weekly telephone calls, and follow-up (8 weeks after the intervention) were protablevided. The data were collected by the Kidney Transplant Questionnaire (KTQ-25) completed before and after the intervention by the two groups, and the Renal Transplantation Complications Checklist completed after 8 weeks. Data analysis was performed in each group before and after the intervention and between the two groups after the intervention via chi-square, Fisher’s exact test, paired t-test, and independent t-test. Results: The results showed a significant difference between the intervention and control groups in the physical dimension (P = 0.002). No significant difference was observed between the two groups in the remaining dimensions and the overall QoL. A significant difference was found between the two groups in terms of infection (P = 0.04), but no difference was observed between the two groups in terms of re-admission and transplant rejection (P &gt; 0.05). Conclusions: The educational package affected all dimensions of QoL, especially the physical dimension and infection (as an acute complication of renal transplant); it improved QoL and reduced infection in the intervention group. Therefore, this package can be considered in the management plans of renal transplant recipients. Administration of this package can help understand the patients’ needs and requests and improve their health-related behaviors.

Protective Effect of Subcutaneous Drains on Wound Infections in Kidney Transplantation

Protective Effect of Subcutaneous Drains on Wound Infections in Kidney Transplantation