Urinary tract infections during the first year after renal transplantation: one center's experience and a review of the literature

Asymptomatic Bacteriuria in Kidney Transplant Recipients-A Narrative Review

Urinary tract infections (UTIs) are the most prevalent complications in kidney transplant (KTx) recipients. The most frequent finding in this group of patients is asymptomatic bacteriuria (ASB). Here, we provide an overview of the available evidence regarding ASB in KTx recipients, including its etiopathology, clinical impact and management. There is a growing body of evidence from clinical trials that screening for and treating ASB is not beneficial in most KTx recipients. However, there are insufficient data to recommend or discourage the use of a "screen-and-treat strategy" for ASB during the first 1-2 months post-transplant or in the case of an indwelling urinary catheter. Despite its frequency, ASB after KTx is still an understudied phenomenon.

Impact of different urinary tract infection phenotypes within the first year post-transplant on renal allograft outcomes

In this study, we investigated the clinical impact of different urinary tract infection (UTI) phenotypes occurring within the first year after renal transplantation. The population included 2368 transplantations having 2363 UTI events. Patients were categorized into four groups based on their compiled UTI events observed within the first year after transplantation: (i) no colonization or UTI (n = 1404; 59%), (ii) colonization only (n = 353; 15%), (iii) occasional UTI with 1-2 episodes (n = 456; 19%), and (iv) recurrent UTI with ≥3 episodes (n = 155; 7%). One-year mortality and graft loss rate were not different among the four groups, but patients with recurrent UTI had a 7-10 ml/min lower eGFR at year one (44 ml/min vs. 54, 53, and 51 ml/min; p < .001). UTI phenotypes had no impact on long-term patient survival (p = .33). However, patients with recurrent UTI demonstrated a 10% lower long-term death-censored allograft survival (p < .001). Furthermore, recurrent UTI was a strong and independent risk factor for reduced death-censored allograft survival in a multivariable analysis (HR 4.41, 95% CI 2.53-7.68, p < .001). We conclude that colonization and occasional UTI have no impact on pertinent outcomes, but recurrent UTI are associated with lower one-year eGFR and lower long-term death-censored allograft survival. Better strategies to prevent and treat recurrent UTI are needed.

Allograft Vesicoureteral Reflux after Kidney Transplantation

Allograft vesicoureteral reflux (VUR) is a leading urological complication of kidney transplantation. Despite the relatively high incidence, there is a lack of consensus regarding VUR risk factors, impact on renal function, and management. Dialysis vintage and atrophic bladder have been recognized as the most relevant recipient-related determinants of post-transplant VUR, whilst possible relationships with sex, age, and ureteral implantation technique remain debated. Clinical manifestations vary from an asymptomatic condition to persistent or recurrent urinary tract infections (UTIs). Voiding cystourethrography is widely accepted as the gold standard diagnostic modality, and the reflux is generally graded following the International Reflux Study Committee Scale. Long-term transplant outcomes of recipients with asymptomatic grade I-III VUR are yet to be clarified. On the contrary, available data suggest that symptomatic grade IV-V VUR may lead to progressive allograft dysfunction and premature transplant loss. Therapeutic options include watchful waiting, prolonged antibiotic suppression, sub-mucosal endoscopic injection of dextranomer/hyaluronic acid copolymer at the site of the ureteral anastomosis, and surgery. Indication for specific treatments depends on recipient’s characteristics (age, frailty, compliance with antibiotics), renal function (serum creatinine concentration < 2.5 vs. ≥ 2.5 mg/dL), severity of UTIs, and VUR grading (grade I-III vs. IV-V). Current evidence supporting surgical referral over more conservative strategies is weak. Therefore, a tailored approach should be preferred. Properly designed studies, with adequate sample size and follow-up, are warranted to clarify those unresolved issues.

Urinary Tract Infections in the First 6 Months after Renal Transplantation

Purpose

Urinary tract infections (UTIs) are common in the first 6 months after renal transplantation, and there are only limited data about UTIs after transplantation in Saudi Arabia in general.

Methods

A retrospective study from January 2017 to May 2020 with 6-month follow-up.

Results

279 renal transplant recipients were included. Mean age was 43.4 ± 16.0 years, and114 (40.9%) were women. Urinary stents were inserted routinely during transplantation and were removed 35.3 ± 28 days postoperatively. Ninety-seven patients (35%) developed urinary tract infections (UTIs) in the first six months after renal transplantation. Of those who developed the first episode of UTI, the recurrence rates were 57%, 27%, and 14% for having one, two, or three recurrences, respectively. Late urinary stent removals, defined as more than 21 days postoperatively, tended to have more UTIs (OR: 1.43, P: 0.259, CI: 0.76–2.66). Age >40, female gender, history of neurogenic bladder, and transplantation abroad were statistically significant factors associated with UTIs and recurrence. Diabetes, level of immunosuppression, deceased donor renal transplantation, pretransplant residual urine volume, or history of vesicoureteral reflux (VUR) was not associated with a higher incidence of UTIs. UTIs were asymptomatic in 60% but complicated with bacteremia in 6% of the cases. Multidrug resistant organisms (MDROs) were the causative organisms in 42% of cases, and in-hospital treatment was required in about 50% of cases. Norfloxacin + Bactrim DD (160/800 mg) every other day was not associated with the lower risk of developing UTIs compared to the standard prophylaxis daily Bactrim SS (80/400 mg).

Conclusion

UTIs and recurrence are common in the first 6 months after renal transplantation. Age >40, female gender, neurogenic bladder, and transplantation abroad are associated with the increased risk of UTIs and recurrence. MDROs are common causative organisms, and hospitalization is frequently required. Dual prophylactic antibiotics did not seem to be advantageous over the standard daily Bactrim.

Incidence and risk factors for urinary tract infections in the first year after renal transplantation

Background

The most common infections among renal transplant patients are urinary tract infections (UTI). Our main objective in this study is to determine the incidence of UTIs in patients who have undergone renal transplantation in our hospital, to identify the causative microbiological agents, risk factors and determine the effects of UTI on short-term graft survival.

Methods

Urinary tract infections, which developed within the first year of renal transplantation, were investigated. Patients were compared regarding demographic, clinical, laboratory characteristics and graft survival.

Results

102 patients were included in our study. Fifty-three patients (53%) were male and 49 (48%) were female. Sixty-seven urinary tract infection attacks in 21 patients (20.5%) were recorded. Age (p = 0.004; 95% Confidence Interval [CI]: 1.032–1.184), longer indwelling urinary catheter stay time (p = 0.039; 95% Confidence Interval [CI]: 1.013–1.661) and urologic complications (p = 0.006; 95% Confidence Interval [CI]: 0.001–0.320) were found as risk factors for UTI development in the first year of transplantation. Escherichia coli and Klebsiella pneumoniae were the most frequently isolated microorganisms. Of these bacteria, 63.2% were found to be extended spectrum beta lactamase (ESBL) positive. Multidrug resistant microorganisms (MDROs) were more frequent in male patients (32 episodes in males vs. 14 episodes in females, p = <0.001). UTI had no negative impact on short-term graft survival.

Conclusion

Our study results represent the high incidence of UTI with MDROs in KT recipients. Infection control methods should be applied even more vigorously especially in male transplant patients since a higher incidence of UTI caused by resistant microorganisms was reported in male patients.

Patient and allograft outcomes after kidney transplant for the Indigenous patients in the United States

Background

The objective is to assess cardiovascular (CV), malignancy, infectious, graft outcomes and tacrolimus levels for the Indigenous patients compared to Whites after kidney transplant (KTx).

Methods

165 Indigenous and 165 White patients matched for the KTx year at Mayo Clinic Arizona from 2007–2015 were studied over a median follow-up of 3 years. Propensity score was calculated to account for baseline differences.

Results

Compared to Whites, Indigenous patients had the following characteristics: younger age, more obesity, diabetes, hypertension, and required dialysis prior to KTx (p<0.01). Indigenous patients had longer hospital stay for KTx, shorter follow-up and lived further from the transplant center (p<0.05). 210 (63.6%) received deceased donor KTx and more Whites received a living donor KTx compared to Indigenous patients (55.2% vs 17.6%, p<0.0001). Post-KTx, there was no difference in the CV event rates. The cumulative incidence of infectious complications was higher among the Indigenous patients (HR 1.81, p = 0.0005, 48.5% vs 38.2%, p = 0.013), with urinary causes as the most common. Malignancy rates were increased among Whites (13.3% vs 3.0%, p = 0.001) with skin cancer being the most common. There was a significant increase in the dose normalized tacrolimus level for the Indigenous patients compared to Whites at 1 months, 3 months, and 1 year post-KTx. After adjustment for the propensity score, there was no statistical difference in infectious or graft outcomes between the two groups but the mean number of emergency room visits and hospitalizations after KTx was significantly higher for Whites compared to Indigenous patients.

Conclusions

Compared to Whites, Indigenous patients have similar CV events, graft outcomes and infectious complications after accounting for baseline differences.

Predictive factors and management of urinary tract infections after kidney transplantation: a retrospective cohort study

BACKGROUND

Urinary tract infection (UTI) is one of the most common infectious complications in kidney transplant recipients. The aims of our study were to identify possible predictive factors for UTI and advocate for the management of UTI after kidney transplantation (KT).

METHODS

Between January 2013 and December 2018, 182 adult patients with end-stage kidney disease who underwent KT were retrospectively analyzed. Patients who had urinary symptoms and positive urine culture were diagnosed with UTI. The types of urinary bacteria causing UTIs were also examined.

RESULTS

UTIs occurred in forty-one patients (25.1%), and the median time to UTI onset (UTI-free survival) after KT was 189 days. The Cox hazard regression analysis showed that the predictive factors for UTI onset were as follows: posttransplant urinary catheterization, including indwelling urinary catheterization and clean intermittent catheterization; a maximum bladder capacity before KT of less than 150 ml; and a low serum albumin level at 1 month after KT. The most common causative agent was Escherichia coli (56.6%), followed by Enterococcus spp. (15.6%) and Klebsiella spp.

CONCLUSIONS

Kidney transplant recipients with prolonged postoperative malnutrition, posttransplant voiding dysfunction and/or urinary storage disorder had an increased risk of UTI. Bladder function tests, such as uroflowmetry, postvoid residual urine tests, and urodynamic tests, were needed to predict UTI. For patients with malnutrition, care should be taken to ensure sufficient calorie intake. Kidney transplant recipients who develop UTI should be treated as complicated UTI patients.

Five compelling UTI questions after kidney transplant

PURPOSE

Urinary tract infection (UTI) is the most common bacterial infection among infectious complications in kidney transplant recipients (KTR). After transplantation, infections can result from surgical complications, donor-derived infections, pre-existing recipient infections, and nosocomial infections. Post-transplant infection is still a major cause of morbidity, mortality, graft dysfunction and rejection. In this paper, we aimed to review a few compelling questions in kidney transplantation (KTX).

METHODS

To identify relevant clinical questions regarding KTX and UTI a meeting was conducted among physicians involved in the KT program in our hospital. After discussion, several clinically relevant questions related to UTI after KTX. The 5 first rated in importance were judged generalizable to other clinical settings and selected for the purposes of this review.

RESULTS

Nearly half of the patients present in the first three months of transplant with UTI. The most common uropathogens in post-transplant UTIs are Escherichia coli, Klebsiella pneumoniae, and Enterococcus faecalis. Risk factors for UTI include female sex, advanced age, recurrent UTI before transplant, prolonged urethral catheterization, delayed graft function, and cadaveric kidney transplant.

CONCLUSION

The incidence of post-transplant UTI is similar in both developed and developing countries. E.coli is the most common pathogen in most of studies. Cadaveric donor and post-dialysis transplantation are defined as independent risk factors for post-transplant UTI. Further studies are still required to identify risk factors after kidney transplantation and UTI's importance for graft function and patient outcome.

Risk factors for febrile urinary tract infections in the first year after pediatric renal transplantation

Urinary tract infection is the most common infectious complication following kidney transplant. Anatomic abnormalities, bladder dysfunction, a positive history of febrile urinary tract infection, and recipient age are reported risk factors. The aim of this study was to determine the risk factors for fUTI, which necessitated hospitalization in the first year after renal transplantation in our pediatric transplant population. A retrospective review of 195 pediatric patients who underwent kidney transplant between 2008 and 2017 from a single institution was performed. All patients admitted to the hospital with fUTI were marked for further analyses. The risk factors including age, gender, dialysis type, history of urologic disorders, and preoperative proteinuria for fUTI in the first year after kidney transplantation and graft survivals were investigated. Independent-sample t test and chi-square tests were used for univariate analysis. Exhaustive CHAID algorithm was used for multivariate analysis. The data of 115 male and 80 female patients were retracted. The mean ages of our cohort for males and females were 9.5 ± 5.1 and 10 ± 4.8 years, respectively. The age of the patients at transplant and their gender were found to be a statistically significant risk factors for developing fUTIs. Multivariate analysis showed that fUTI was common in female patients and a subgroup of male patients who had preoperative proteinuria, but no neurogenic bladder had higher risk compared with male patients without proteinuria. Patient surveillance and antibiotic prophylaxis algorithms can be developed to prevent febrile urinary tract infections seen after pediatric kidney transplantation in risky population.

Beyond death and graft survival-Variation in outcomes after kidney transplantation. Results from the NSQIP Transplant beta phase

The National Surgical Quality Program (NSQIP) Transplant was designed by transplant surgeons from the ground up to track posttransplant outcomes beyond basic recipient and graft survival. After an initial pilot phase, the program has expanded to 29 participating sites and enrolled more than 4300 recipient-donor pairs into the database, including 2876 complete kidney transplant cases. In this analysis, surgical site infection (SSI), urinary tract infection (UTI), and reoperation/intervention were evaluated for kidney transplant recipients. We observed impressive variation in the crude incidence between sites for SSI (0%-17%), UTI (0%-14%), and reoperation/intervention (0%-25%). After adjustment for donor and recipient factors, 2 sites were outliers with respect to their incidence of UTI. For the first time, the field of transplantation has data that demonstrate variation in kidney recipient surgical outcomes between sites. More importantly, NSQIP Transplant provides a powerful platform to improve care beyond basic patient and graft survival.

Host and pathogen factors in Klebsiella pneumoniae upper urinary tract infections in renal transplant patients

PURPOSE

To analyse the role of virulence factors (VFs) and host in Klebsiella pneumoniae upper urinary tract infections (UTIs) in renal transplant (RTx) recipients.

METHODOLOGY

Clinical and demographic data were registered prospectively. Phylogenetic background of K. pneumoniae isolates was analysed by PCR melting profiles (MP) and the following VFs genes: fimH-1, uge, kpn, ycfM, mrkD, rmpA, magA, hlyA, cnf-1, irp-1, irp-2, fyuA, entB, iutA, iroN by PCR.

RESULTS

We studied urine cultures and clinical data from 61 episodes of K. pneumoniae UTI in 54 RTx recipients. There were 32 cases of AB (53%), 10 cases of lower UTI (16%), 19 cases of AGPN (31%), including six cases of bacteraemia. In total, 74 % of strains were extended-spectrum beta-lactamase+, and there were two carbapenemase-producing strains. PCR MP typing showed a diverse population with 52 different genetic profiles of K. pneumoniae. Analysis of the DNA profiles indicated 45 unrelated, unique genotypes and 7 related (16 isolates from 15 patients) genotypes. Urine flow impairment emerged as an independent predictor of K. pneumoniae upper UTIs (OR 14.28, CI 2.7-75.56, P 0.002), while we did not find any association between the profile of VFs and developing upper UTIs. The prevalence of the uge gene was lower in RTx patients on everolimus when compared to isolates from patients not receiving mTOR inhibitors (33.3 % vs 82.8 % P<0.05).

CONCLUSIONS

K. pneumoniae upper UTI may be a marker of urine flow impairment. Bacterial VFs could not discriminate between upper and lower UTIs. However, immunosuppression may influence the selection of particular VFs.

A randomized clinical trial comparing Nitrofurazone-coated and uncoated urinary catheters in kidney transplant recipients: Results from a pilot study

BACKGROUND

Urinary tract infections are frequent complications early after kidney transplantation, and the use of antimicrobial coated catheters in settings other than transplantation has shown promising results for infection prevention. The purpose of this study was to compare the efficacy of Nitrofurazone-coated silicone urinary catheters with non-impregnated silicone urinary catheters in reducing bacteriuria and urinary tract infections in kidney transplant recipients.

METHODS

This single-center study, randomized controlled trial at the Hospital do Rim, a tertiary referral center in kidney transplantation, located in São Paulo, Brazil. Subjects involved living donor kidney transplant recipients, and were randomized 1:1 ratio with a computer-generated system to a Nitrofurazone-coated silicone urinary catheter and non-impregnated silicone urinary catheter from March 2013 to December 2014. Patients with asymptomatic bacteriuria or urinary tract infection at baseline, deceased kidney transplant donors, patients with known hypersensitivity to nitrofurantoin, pregnancy, and those refusing to sign the informed consent form were excluded from the study.

RESULTS

Two hundred fourteen subjects were randomized and one hundred seventy-six completed the study. There were no differences in the rates of asymptomatic bacteriuria (12.5% in the Nitrofurazone group and 11.4% in the control group, P = 0.99) and urinary tract infection (8% and 6.8%, P = 0.99) and the incidence of side effects was more frequent in the Nitrofurazone-impregnated silicone urinary catheter group (46.6% and 26.1%, P = 0.007).

CONCLUSION

The study suggests that there is no beneficial effect of the employment of Nitrofurazone-coated urinary catheter.

TRIAL REGISTRATION NUMBER

ISRCTN57888785.

Managing recurrent urinary tract infections in kidney transplant patients

INTRODUCTION

Recurrent urinary tract infections (UTI) are a common clinical problem in kidney transplant recipients. Due to the complex urological anatomy derived from the implantation of the kidney graft, the spectrum of the disease and the broad underlying pathophysiological mechanisms. Recurrent UTI worsen the quality of life, decrease the graft survival and increase the costs of kidney transplantation. Areas covered: In this review, we describe the definitions, clinical characteristics, pathophysiological mechanisms and microbiology of recurrent urinary tract infections in kidney transplantations. The actual published literature on the management of recurrent urinary tract infections is based on case series, observational cohorts and very few clinical trials. In this review, the available evidence is compiled to propose evidence-based strategies to manage these complex cases. Expert commentary: The management of recurrent urinary tract infections in kidney transplant patients requires a proper diagnosis of the underlying mechanism. Early identification of structural or functional urological abnormalities, potentially amenable for surgical correction, is crucial for a successful management. The use of antibiotics to prevent recurrent infections should be carefully evaluated to avoid side effects and emergence of antibiotic-resistant microorganisms.

Epidemiology, susceptibility, and risk factors for acquisition of MDR/XDR Gram-negative bacteria among kidney transplant recipients with urinary tract infections

Background

Multiple drug resistant/extensively drug resistant (MDR/XDR) Gram-negative urinary tract infections (UTIs) represent a growing threat to kidney transplant recipients. This retrospective study aimed to assess the incidence and microbiological profile of MDR/XDR Gram-negative UTIs, to identify drug susceptibility of MDR/XDR bacteria, and to determine the potential risk factors for MDR/XDR UTIs in kidney recipients.

Materials and methods

During the study period, 1569 patients underwent consecutive kidney transplantation in two transplantation centers. We studied the demographics, clinical characteristics, and urine culture data from kidney recipients with MDR/XDR Gram-negative UTIs, and verified the risk factors associated with MDR/XDR infections.

Results

Eighty-one kidney recipients yielded 88 episodes of MDR/XDR Gram-negative UTIs with five patients (6.2%) succumbing to all-cause in-hospital mortality. The most frequently isolated bacterium was Escherichia coli (62.5%). Almost all MDR/XDR Gram-negative bacteria were resistant to first- and second-generation cephalosporin, and monocyclic beta-lactam. They were relatively sensitive to meropenem, amikacin, and tigecycline. As for the 12 XDR bacteria, all of them were resistant to meropenem and 25% of them were resistant to tigecycline. All XDR Acinetobacter baumannii and E. coli were susceptible to tigecycline. Nosocomial infection (odds ratio [OR] = 11.429, 95% CI = 1.311–99.625, P = 0.027) was the only independent predictor of MDR/XDR Gram-negative UTIs. Non-fermenting bacterial infection (OR = 20.161, 95% CI = 3.409–119.240, P = 0.001), polycystic kidney disease (OR = 39.871, 95% CI = 1.979–803.384, P = 0.016), and serum creatinine level > 1.5 mg/dL (OR = 8.688, 95% CI = 1.354–55.747, P = 0.023) were significantly different between XDR and MDR Gram-negative UTIs.

Conclusion

Meropenem, amikacin, and/or tigecycline can be prescribed for MDR/XDR Gram-negative infections. Tigecycline can also be prescribed for XDR A. baumannii and E. coli. Nosocomial infection was a risk factor for MDR/XDR Gram-negative UTIs, while XDR UTIs were associated with non-fermenting bacterial infection, polycystic kidney disease, and impaired renal function.

The challenge of urinary tract infections in renal transplant recipients

Urinary tract infections (UTI) are an important cause of morbidity and mortality in renal transplant patients. These infections are quite common, and the goal of care is to identify and reduce risk factors while providing effective prophylaxis and treatment. Better understanding of long-term outcomes from these infections has led to the distinctions among UTI, recurrent UTI, and asymptomatic bacteriuria (ASB), and that each requires a different therapeutic approach. Specifically, new research has supported the perspective that asymptomatic bacteriuria should not be treated. Symptomatic UTI, on the other hand, requires intervention and remains an ongoing challenge for infectious disease clinicians. Many bacteria species are responsible for UTI in renal transplant patients, and in recent years there has been a global rise in infection caused by bacteria with newly acquired antibacterial resistance genes. Many renal transplant patients who experience UTI will also have multiple recurring episodes, which likely has a distinct pathophysiological mechanism leading to chronic colonization of the urinary tract. In these cases, long-term management includes bacterial suppression, which aims to reduce rather than eliminate bacteria to levels below the threshold for symptomatic infection. This review will address the current understanding of UTI epidemiology, pathogenesis, and risk factors in the renal transplant community, and also focus on current prevention and treatment strategies for patients who face an environment of increasingly antibiotic-resistant bacteria.

Urinary tract infections caused by ESBL-producing Enterobacteriaceae in renal transplant recipients: A systematic review and meta-analysis

BACKGROUND

Urinary tract infections (UTIs) are the most common infectious complications among renal transplant recipients (RTR). UTIs caused by extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-PE) have been associated with inferior clinical outcomes and increased financial burden.

METHODS

We performed a systematic review and meta-analysis by searching through the PubMed and EMBASE databases (to May 20, 2016) and identifying studies that reported data on the number of RTR who developed an ESBL-PE UTI.

RESULTS

Our analysis included seven studies, out of 357 non-duplicate articles, that provided data on 2824 patients. Among them, 10% (95% confidence interval [CI] 4%-17%) developed an ESBL-PE UTI over their follow-up periods. The proportion of RTR affected by an ESBL-PE UTI was 2% in North America (95% CI 1%-3%), 5% in Europe (95% CI 4%-6%), 17% in South America (95% CI 10%-27%), and 33% in Asia (95% CI 27%-41%). In addition, patients affected with an ESBL-PE UTI were 2.75-times (95% CI 1.97-3.83) more likely to suffer a recurrent UTI.

CONCLUSIONS

Based on a limited number of studies, one in 10 RTR will develop a UTI caused by an ESBL-PE, and these patients face an almost 3 times greater risk of recurrence. A more rigorous monitoring of RTR, both during and after resolution of their infection, should be evaluated in order to reduce the incidence and the clinical impact of these resistant infections.

Risk Factors for Urinary Tract Infections in Renal Allograft Recipients: Experience of a Tertiary Care Center in Hyderabad, South India

Renal transplantation is an effective and commonly performed procedure for end-stage renal disease. Urinary tract infections are a major cause of morbidity and mortality in renal transplant patients. As data on postrenal transplant urinary tract infections from the Indian subcontinent are limited, the present study was conducted to estimate the burden of urinary tract infections in this vulnerable group of patients. This was a prospective study on patients undergoing renal transplantation in 2014 at our tertiary hospital in South India with a follow-up of 2 years to evaluate the risk factors for urinary tract infections. The prevalence of urinary tract infections was 41.9% with a male preponderance of 76.9%. Mean age of the 31 patients was 32.4 ± 10.2 years (range: 16-55 years). Gram-negative bacilli were the most common isolates with Escherichia coli being the predominant pathogen (53.3%). All the infections occurred within 1 year of transplantation with delayed graft function (P < 0.001; confidence interval [CI]: 29.0-96.3) and prolonged hospital stay (P = 0.0281; CI: 42.1-99.6) being the significant risk factors for acquiring urinary tract infections. Carbapenemase production was noted in 33.3% of isolates and all the Gram-negative organisms isolated in the 1st month of transplantation were carbapenem-resistant (CR) E. coli. The high rate of carbapenem-resistant organisms in the early posttransplant period is a point of concern, especially with cadaver transplants. Infection control practices and catheter care need to be strictly monitored to minimize the risk for UTI in the immediate posttransplant period.

Increased resistance of gram-negative urinary pathogens after kidney transplantation

BACKGROUND

Urinary tract infection is the most common complication after kidney transplantation. It can cause severe sepsis and transplant loss. Emergence of drug resistance among gram-negative urinary pathogens is the current challenge for urinary tract infection treatment after kidney transplantation.

METHODS

This study analyzes the antimicrobial susceptibility of gram-negative urinary pathogens after kidney transplantation from 2009 to 2012 at the Transplant Outpatient Clinic of the University Hospital Essen, Germany. Kidney transplant patients at the University Hospital Essen receive regular follow up examinations after transplantation. Midstream urines were examined for bacteriuria at each follow up visit.

RESULTS

From 2009 to 2012 15.741 urine samples were obtained from 859 patients. In 2985 (19%) samples bacterial growth was detected. The most frequently detected gram-negative bacteria were E.coli 1109 (37%), Klebsiella spp. 242 (8%) and Pseudomonas aeruginosa 136 (4.5%). Klebsiella spp. showed a significant increase of resistance to trimethoprim-sulfamethoxazole by 19% (p = 0.02), ciprofloxacin by 15% (p = 0.01) and ceftazidime by 17% (p = 0.004). E.coli and P. aeruginosa isolates presented no significant differences of antimicrobial susceptibility to the analyzed antibiotics.

CONCLUSIONS

Antimicrobial resistance of Klebsiella spp. increased significant to trimethoprim-sulfamethoxazole, ciprofloxacin and ceftazidime from 2009 to 2012.

Urinary Tract Infections in Kidney Transplant Recipients Hospitalized at a Transplantation and Nephrology Ward: 1-Year Follow-up

INTRODUCTION

The aim of this study was to investigate risk factors for urinary tract infections (UTI), the causative organisms of UTI and also their management and treatment. In addition, we evaluated the effects of UTI on renal graft function.

METHODS

This analysis included 107 kidney transplant recipients (64% women) with a diagnosis of UTIs confirmed by positive results on urine culture. Type of pathogens, sensitivity to drugs, risk factors for infection, incidence of urosepsis, hospitalization period, treatment methods, and recurrence rates were analyzed. Statistical analysis was performed by using Pearson's χ(2) test, Yates' χ(2) test, the Student t test, Welch's t test, the Mann-Whitney U test, Fisher's exact test, and the Shapiro-Wilk normality test.

RESULTS

The most common species isolated from urine samples included Escherichia coli (42%), Klebsiella pneumoniae (15%), and Enterococcus faecalis (10%). The percentage of multidrug-resistant strains was 31%, and urosepsis was diagnosed in 16% of patients. Recurrences developed in 76% of infected patients. Bricker ureterointestinal anastomosis was performed in 11% of patients. Risk factors for severe infections included: pre-transplantation urinary tract surgery (P = .02), double-J stent insertion (more common in men) during KTx (N = 34; 32%), (P = .021), reoperations following transplantation (P = .36), elevated tacrolimus levels at the time of infection (P = .024). Severe infections were diagnosed in patients with lower eGFRs, were associated with a need for longer hospitalization (P = .04) and escalation of antibacterial treatment. Carbapenems were used in 22 patients (20.5%).

CONCLUSIONS

UTIs were more common in women, in patients with impaired function of the kidney transplant, and in those with a history of urinary tract interventions. Severe infections were associated with a risk of urosepsis, longer hospitalization, and a need for escalation of antibiotic treatment.

Should Asymptomatic Bacteriuria Be Systematically Treated in Kidney Transplant Recipients? Results From a Randomized Controlled Trial

The indication for antimicrobial treatment of asymptomatic bacteriuria (AB) after kidney transplantation (KT) remains controversial. Between January 2011 and December 2013, 112 KT recipients that developed one episode or more of AB beyond the second month after transplantation were included in this open-label trial. Participants were randomized (1:1 ratio) to the treatment group (systematic antimicrobial therapy for all episodes of AB occurring ≤24 mo after transplantation [53 patients]) or control group (no antimicrobial therapy [59 patients]). Systematic screening for AB was performed similarly in both groups. The primary outcome was the occurrence of acute pyelonephritis at 24-mo follow-up. Secondary outcomes included lower urinary tract infection, acute rejection, Clostridium difficile infection, colonization or infection by multidrug-resistant bacteria, graft function and all-cause mortality. There were no differences in the primary outcome in the intention-to-treat population (7.5% [4 of 53] in the treatment group vs. 8.4% [5 of 59] in the control group; odds ratio [OR] 0.88, 95% confidence interval [CI] 0.22-3.47) or the per-protocol population (3.8% [1 of 26] in the treatment group vs. 8.0% [4 of 50] in the control group; OR 0.46, 95% CI 0.05-4.34). Moreover, we found no differences in any of the secondary outcomes. In conclusion, systematic screening and treatment of AB beyond the second month after transplantation provided no apparent benefit among KT recipients (NCT02373085).

Differential Characteristics of Kidney Transplant Recipients According to 1-Year Chronic Kidney Disease Stage 3a and Stage 3b Graft Function

The outcomes of transplantation have improved, but more than 50% of kidney transplantation (KT) recipients are still reported to have renal function of chronic kidney disease (CKD) stage 3 at 1 year after KT. We reviewed all 1235 patients who received a KT in our institution between 2008 and 2012. Among these recipients, 77 and 289 cases were included in the estimated glomerular filtration rate (eGFR) at 1 year after KT 30-44 (CKD stage 3b) group and eGFR 45-59 (CKD stage 3a) group, respectively. Longer duration of dialysis (odds ratio [OR] = 1.007, 95% confidence interval [CI], 1.000-1.014, P = 0.047), older donors (OR = 1.064, 95% CI, 1.031-1.098, P < 0.001), delayed graft function (OR = 3.601, 95% CI, 1.031-1.098, P < 0.001), BK virus infection (OR = 2.567, 95% CI, 1.242-5.305, P = 0.011), and pneumonia (OR = 4.451, 95% CI, 1.388-14.279, P = 0.012) were contributing factors to eGFR 30-44 mL/min. Especially, ureteral stricture occurred more frequently in eGFR 30-44 group of deceased donor KT. However, acute rejection was not a significant risk factor of lower eGFR. Graft survival was better in the eGFR 45-59 group. However, this difference was smaller in deceased donor KT. Infections and urologic complications are also important contributing factors of lower graft function in CKD stage 3. In addition, dividing CKD stage 3 into subgroups might be more useful in living donor kidney transplantation.

Incidence, risk factors, and the impact of allograft pyelonephritis on renal allograft function

BACKGROUND

The impact of allograft pyelonephritis (AGPN) on renal allograft function is controversial. In this study, we evaluated the incidence, risk factors, and the impact of AGPN on renal allograft function.

METHODS

Retrospective cohort study in adult renal allograft recipients with 1-year follow-up after transplantation (Tx). Renal allograft function was evaluated by estimated glomerular filtration rate (eGFR) (by Modification of Diet in Renal Disease formula) and 24-h urine protein excretion.

RESULTS

A total of 431 renal allograft recipients were analyzed; 57 (13.2%) developed AGPN within 1 year after Tx. Median time between Tx and AGPN was 50 days. Risk factors for AGPN were the presence of a urological catheter (odds ratio [OR] = 18.93, 95% confidence interval [CI] = 8.00-44.81, P < 0.001) and preceding asymptomatic bacteriuria (ASB) (OR = 2.16, 95% CI = 1.20-3.90, P = 0.009). In 72.7%, the causative microorganism of ASB was identical to that of the succeeding AGPN episode. Multivariable linear regression analysis showed that experiencing AGPN did not decrease the eGFR (P = 0.61) nor did increased proteinuria (P = 0.29) 1 year after Tx. For the eGFR, an interaction was found between AGPN/bacteriuria (BU) and acute rejection (AR): the group experiencing BU preceding AR had significantly (P < 0.001) lower eGFR compared with the group that experienced only AR (21 mL/min/1.73 m² vs. 48 mL/min/1.73 m² ), as a result of increased prevalence of combined rejections within the BU group.

CONCLUSION

Indwelling urological catheters and preceding ASB are associated with developing AGPN. An incident of AGPN itself does not impair renal allograft function 1 year after Tx. However, a relevant interaction occurs between BU and AR, in which the sequence of occurrence of these 2 events synergistically impairs the eGFR.

Bloodstream infections after solid-organ transplantation

Solid-organ transplantation (SOT) has become the preferred strategy to treat a number of end-stage organ disease, because a continuous improvement in survival and quality of life. While preventive strategies has decreased the risk for classical opportunistic infections (such as viral, fungal and parasite infections), bacterial infections, and particularly bloodstream infections (BSIs) remain the most common and life-threatening complications in SOT recipients. The source of BSI after transplant depends on the type of transplantation, being urinary tract infection, pneumonia, and intraabdominal infections the most common infections occurring after kidney, lung and liver transplantation, respectively. The risk for candidemia is higher in abdominal-organ than in thoracic-organ transplantation. Currently, the increasing prevalence of multi-drug resistant (MDR) Gram-negative pathogens, such as extended-spectrum betalactamase-producing Enterobacteriaciae and carbapenem-resistant Klebsiella pneumoniae, is causing particular concerns in SOT recipients, a population which presents several risk factors for developing infections due to MDR organisms. The application of strict preventive policies to reduce the incidence of post transplant BSIs and to control the spread of MDR organisms, including the implementation of specific stewardship programs to avoid the overuse of antibiotics and antifungal drugs, are essential steps to reduce the impact of post transplant infections on allograft and patient outcomes.

[Urological follow-up and development of cancer after renal transplantation]

BACKGROUND

The number of renal transplant recipients is rising, as well as graft and recipient survival. The mainstay of urological follow-up is to ensure urine transport and voiding function; also, the diagnosis and treatment of urological malignancies following renal transplantats is growing in importance. As urological malignancies are one of the three most common tumors following renal transplantation (RT), meticulous and regular urological evaluation is a central part of follow-up care after RT.

RECOMMENDATIONS

Urological evaluation following RT must ensure correct urine transport and voiding function. Transplant ureter strictures, relevant ureteral reflux and voiding dysfuntion (e.g., neurologic dysfunction, benign prostate hypeplasia) must be excluded or treated. Urinary tract infection (UTI), which can be life threatening in the immunosuppressed transplant recipient, must be diagnosed and treated consequently and for an adequate period of time. Prophylaxis of UTIs is indicated in patients with recurrent symptomatic UTI as well as in the initial 6 months following renal transplantation. Asymptomatic bacteriuria must not necessarily be treated. The incidence of urological malignancies like renal cell carcinoma, urothelial cancer of the bladder, and penile carcinoma is increased following RT, while the incidence of prostate and testis cancer is the same as in the nontransplant population. Surgical and nonsurgical treatment options do not differ from the normal population. Adaptation, cessation, or switching of the immunosuppressive regimen in case of urologic malignancy must be decided on the individual recipient basis.