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

Bacterial Colonization in Double J Stent and Bacteriuria in Post-Renal Transplant Patients

Background and objective

Urinary tract infections (UTI) in kidney transplant recipients can cause significant morbidity and negatively impact both, graft and patient survival. Ureteric stenting in renal transplantation is aimed at reducing the risks of complications like ureteric leak and stenosis. Ureteric stents are not without their potential complications which may include UTI. We aimed to compare urine bacteriology and bacterial colonization of DJ stent following kidney transplantation, and to establish antimicrobial susceptibility to guide the choice of empirical antibiotics in the event of UTI in post-transplant patients with DJ stent.

Materials and methods

This was a prospective study carried out over a year period (February 2020 to January 2021). Eighty post-renal transplant patients with indwelling ureteral stents were recruited for the study. An early morning midstream urine sample was taken for analysis from consenting patients that met the inclusion criteria. All stents were removed via rigid cystoscopy and the distal end of the stent (4cm) was cut off and put in a sterile bottle for microbiological analysis. Sensitivity and resistance were tested against a panel of 19 antibiotics on all microbial isolates. Results were considered statistically significant when p < 0.05.

Results

The mean age of the patients was 47.9+ 12.1 years. Male patients were 60 (75%) while 20 (25%) were females. Fifty-one (52%) patients had hypertension while 25 (26%) had diabetes mellitus. Hypertension and diabetes were noted in 20 (21%) patients while only one patient (1%) had HCV. Prior to renal transplantation, patients had negative urine cultures. The majority of the patients (76, 95%) had their stent retrieved after 4 weeks, 2 (2.5%) of them had stents retrieved after 2 weeks, and 2 (2.5%) had stents retrieved after 8 weeks. There was a significant association between the duration of stent and stent colonization (p=0.031).

No organism was cultured in both the urine and stent in 13 (14.4%) patients. Nine (10%) had positive stent culture with a negative urine culture while 5 (5.6%) had positive urine culture with a negative stent culture. The same organism was noted in both urine and stent in 58 (64.4%) of patients while different organisms were cultured in 5 (5.6%) of the patients. Escherichia coli was the most common organism cultured in the urine of 38 (65.5%) patients and 36 (58.1%) stents, respectively.

The sensitivity pattern shows that the organisms were more susceptible to nitrofurantoin and gentamicin, and resistant to tetracycline and ceftriaxone. Tigecycline showed good susceptibility and poor resistance.

Conclusion

This study shows that stent colonization was slightly higher than urine bacteriology, with both demonstrating similar microbiological patterns. Selection of the initial empiric treatment should be based on local epidemiological data. Initial therapy should be de-escalated to the most narrow-spectrum antibiotics to complete the course of therapy once culture and sensitivity data is available. Antibiotics stewardship will help in reducing the trend of MDR pathogens.

Urinary Tract Infection among Post-renal Transplant Patients in the Department of Nephrology of a Tertiary Care Centre: A Descriptive Cross-sectional Study

Introduction

Urinary tract infection is the most common infection among renal transplant recipients and increases the risk of hospitalization or even death. The study aimed to find the prevalence of urinary tract infection among post-renal transplant patients in the Department of Nephrology of a tertiary care centre.

Methods

This is a descriptive cross-sectional study which was conducted among 217 post-renal transplant patients at the Department of Nephrology of a tertiary care centre from 1st November, 2017 to 31st October, 2018. The study was approved by the Institutional Review Committee (Reference number: 245(6-11-E)2074-75). Convenience sampling was used. The data were entered in Microsoft Excel 2011 and analyzed using the Statistical Package for the Social Sciences version 20.0. Point estimate at 95% Confidence Interval was calculated along with frequency and proportion for binary data and mean with standard deviation for continuous data.

Results

Among 217 patients, urinary tract infection was seen in 27 (12.44%) (8.05-16.83 at 95% Confidence Interval). One (3.70%) patient had the infection within three months of transplant, and 17 (62.96%) had infection after more than a year of transplant.

Conclusions

The prevalence of urinary tract infection among kidney transplant recipients in our study was lower than previous studies done in similar settings.

Keywords

Escherichia coli; hypertension; kidney; transplants.

Acute Allograft Pyelonephritis: Vague Symptoms, Indeterminate Laboratory Results, and the Necessity of Indication Biopsy

OBJECTIVES

In this study, we examined the clinical and biochemical features of biopsy-proven acute pyelonephritis among 769 kidney transplant recipients.

MATERIALS AND METHODS

This cohort study was performed between January 2003 and December 2019 at the University of Health Sciences (Izmir, Turkey). Acute pyelonephritis refers to urinary tract infection with acute graft dysfunction. All patients with suspected acute pyelonephritis underwent diagnostic biopsy and received antibiotic treatment for an average of 14 to 21 days. Patients with acute pyelonephritis (18/769, 2.3%) were categorized into groups of 9 patients each: group 1 developed acute pyelonephritis in the first 6 months, and group 2 developed acute pyelonephritis >6 months posttransplant.

RESULTS

All patients in group 1 had acute graft dysfunction; only 2 (22%) were symptomatic. All patients recovered baseline graft function after treatment. Patients in group 2 had at least 2 laboratory findings that included leukocytosis, neutrophilia, and high C-reactive protein values. Six patients had urine culture positivity. Recurrent pyelonephritis occurred in 3 patients. Four patients had graft loss. Over the mean follow-up of 48.0 ± 28.4 months, 14 patients (78%) were alive with a functioning graft.

CONCLUSIONS

Diagnostic biopsy is of great importance in patients with urinary tract infection accompanied by acute graft dysfunction in the first 6 months after transplant.

Urine and vaginal microbiota compositions of postmenopausal and premenopausal women differ regardless of recurrent urinary tract infection and renal transplant status

Postmenopausal women and renal transplant recipients are at increased risk of recurrent urinary tract infections (RUTI). Urine and vaginal microbiota of premenopausal controls (N = 18) and RUTI cases (18), and of postmenopausal controls (30) and RUTI cases (20) with and without a renal transplant, were characterized using 16S rRNA sequencing. Participants did not have UTI symptoms at the time of sampling. Gram-negative uropathobionts (predominantly Escherichia/Shigella, Pseudomonas, Klebsiella, and Acinetobacter) had a much higher mean relative abundance in urine than vaginal samples, especially in premenopausal women. No statistically significant differences in mean relative abundances of bacterial groups were found within the premenopausal group or within the postmenopausal group by RUTI or renal transplant status without chronic antibiotic use. Comparing postmenopausal to premenopausal women, mean relative abundances of lactobacilli (especially L. crispatus) in urine and vaginal samples and of Gram-negative uropathobionts in urine were lower, and of BV-anaerobes and Gram-positive uropathobionts in urine and vaginal samples were higher. While RUTI in premenopausal women is predominantly caused by Escherichia, the causative organisms in postmenopausal women are likely more diverse. The relative importance of individual organisms is currently unknown. We recommend that future studies, including intervention studies, include longitudinal microbiota assessments.

Caracterización de la infección urinaria y resistencia antimicrobiana en receptores de trasplante renal de un centro colombiano

La infección del tracto urinario (ITU) es una de las principales complicaciones postrasplante renal, los datos a nivel nacional en ese grupo poblacional son limitados.

Objetivos caracterizar la microbiología de las ITU presentadas en receptores de trasplante renal (TxR) en un centro colombiano durante el periodo 2017–2019, los factores relacionados con la resistencia antimicrobiana y el impacto de la ITU en la función del injerto renal.

Métodos estudio de corte transversal ejecutado mediante el análisis de la base de datos de ingresos hospitalarios por urgencias de pacientes receptores de TxR con sospecha clínica de ITU en una institución de cuarto nivel en Bogotá, Colombia. El análisis de datos se ejecutó en STATA 13.0.

Resultados La ITU causó 12,69% de visitas a urgencias en pacientes trasplantados. Los microorganismos aislados fueron: Escherichia coli 52,22%, Klebsiella pneumoniae 16,67%, Pseudomonas aeruginosa 4,44%, Salmonella spp 4,44%, Proteus mirabilis 3,33%, Serratia marcescens 2,22%, Klebsiella oxytoca 2,22%, Citrobacter koseri 1,11%, Enterobacter cloacae 1,11%, otros 2,22%; El urocultivo fue negativo en 10% de los casos. El 28,39% (n:23) de gérmenes aislados fue multisensible mientras que el 71,60% (n:58) expresó algún tipo de patrón de resistencia distribuido así: 68,96% productor de betalactamasa de espectro extendido (BLEE), 15,52% productor de carbapenemasas, 12,06% productor de betalactamasa tipo IRT, 3,45% fue catalogado como multirresistente. 17,78% de los pacientes presentó criterios de urosepsis, no se registró ningún caso de mortalidad asociada a la ITU. La creatinina sérica tuvo un incremento promedio de 0,46 mg/dl durante el episodio de ITU (p: <0,0001) y el antecedente de diabetes mellitus se relacionó con la ITU causada por gérmenes resistentes (p: 0,008).

Conclusiones La ITU es una causa frecuente de atención en urgencias para pacientes receptores de TxR; la Escherichia coli es el microorganismo causal más frecuente y cerca del 70% de los gérmenes aislados presentó algún patrón de resistencia antimicrobiana.

Characterizing the landscape and impact of infections following kidney transplantation

Infections remain a major threat to successful kidney transplantation (KT). To characterize the landscape and impact of post-KT infections in the modern era, we used United States Renal Data System (USRDS) data linked to the Scientific Registry of Transplant Recipients (SRTR) to study 141 661 Medicare-primary kidney transplant recipients from January 1, 1999 to December 31, 2014. Infection diagnoses were ascertained by International Classification of Diseases, Ninth Revision (ICD-9) codes. The cumulative incidence of a post-KT infection was 36.9% at 3 months, 53.7% at 1 year, and 78.0% at 5 years. The most common infections were urinary tract infection (UTI; 46.8%) and pneumonia (28.2%). Five-year mortality for kidney transplant recipients who developed an infection was 24.9% vs 7.9% for those who did not, and 5-year death-censored graft failure (DCGF) was 20.6% vs 10.1% (P < .001). This translated to a 2.22-fold higher mortality risk (adjusted hazard ratio [aHR]: _2.15 2.22_2.29 , P < .001) and 1.92-fold higher DCGF risk (aHR: _1.84 1.91_1.98 , P < .001) for kidney transplant recipients who developed an infection, although the magnitude of this higher risk varied across infection types (for example, 3.11-fold higher mortality risk for sepsis vs 1.62-fold for a UTI). Post-KT infections are common and substantially impact mortality and DCGF, even in the modern era. Kidney transplant recipients at high risk for infections might benefit from enhanced surveillance or follow-up to mitigate these risks.

Lack of Impact of Acute Pyelonephritis on Kidney Graft Survival

BACKGROUND

Urinary tract infection is the most common bacterial infection after kidney transplant. Some studies suggested that urinary tract infection could impair graft survival, but this issue remains debated. The objective of this study was to analyze the association between acute pyelonephritis (APN) and the risk of kidney graft failure.

METHODS

We performed a retrospective cohort study including patients who received a kidney transplant from 2001 to 2009 at a university hospital in Rio de Janeiro, Brazil. They were followed until December 2015. The primary outcome was graft failure. Follow-up of patients who died with a functioning graft was censored on the date of death. Cox proportional hazards method was used in multivariable analysis to assess risk factors for graft failure. The occurrence of the first episode of APN and acute rejection were modeled as time-dependent variables.

RESULTS

A total of 587 patients were included. Of these, 112 recipients (19%) developed 173 episodes of APN. Graft failure occurred in 150 patients (25%) after a median follow-up of 79 months. The factors associated with graft failure in the multivariate analyses were age of the transplant recipient (hazard ratio [HR], 0.97 per year; 95% confidence interval [CI], 0.96-0.99; P < .01), occurrence of delayed graft function (HR, 2.42; 95% CI, 1.72-3.40; P < .01), and acute rejection (HR, 2.71; 95% CI, 1.92-3.82; P < .01). There was no association between APN and graft failure (HR, 1.05; 95% CI, 0.65-1.68; P = .85).

CONCLUSIONS

Our results suggest that the occurrence of APN is not associated with a significant reduction in graft survival after kidney transplant.

Imaging non-vascular complications of renal transplantation

In patients with end-stage renal disease, the treatment of choice for most patients is renal transplantation. Complications that occur after kidney transplant can be broadly divided into vascular and non-vascular categories. Non-vascular complications can further be divided into surgical and medical categories. When evaluating renal transplant imaging, it is helpful to consider the occurrence of complications in a timeline from time of surgery. Ultrasound is often the first modality used for evaluation of renal transplants particularly in the early postoperative period. Contrast-enhanced ultrasound can be a helpful adjunct in evaluating certain complications such as hematoma, rejection, and infection. Computed tomography (CT) is also helpful in accurately diagnosing complications. Surgical complications include perinephric fluid collections (hematoma, urinoma from urine leak, abscess, and lymphocele), urinary obstruction, and incisional fluid collections and hernias. One major category of medical complications that affect the renal parenchyma includes rejection (hyperacute, acute, and chronic), delayed graft function, acute tubular necrosis (ATN), and nephrotoxicity. Infection, renal calculi, and neoplasms such as post-transplant lymphoproliferative disease are medical complications that occur after renal transplantation. It is important for radiologists to be aware of the ultrasound and CT findings of the surgical and medical complications after renal transplant for prompt identification and treatment.