Impact of Urinary Tract Infections in Kidney Transplant Recipients: A 4-Year Single-Center Experience

Effect of urinary tract infection on the outcome of the allograft in patients with kidney transplantation

BACKGROUND

Urinary tract infections (UTIs) are the second most common cause of graft dysfunction, accounting for significant morbidity, and are associated with poor graft and patient survival. This study aimed to assess the association between post-renal transplant UTI and graft outcomes.

METHODS

We examined the effect of UTIs on graft outcomes in patients who underwent renal transplantation surgery between January 2010 and December 2022. The study population included 349 renal transplantations, of which 74 experienced 140 UTI events. Based on the number of UTI episodes, patients were categorized into three groups.

RESULTS

Of the 349 recipients, 275 (74.4%) had no UTI, 47 (18.8%) had non-recurrent UTIs (NR-UTIs), and 27 (6.8%) had recurrent UTIs (R-UTIs). Kaplan-Meier survival analysis showed that post-KT UTI status was a significant factor in graft survival, death-censored graft survival, and patient survival after a follow up of 5 years (log rank, P < 0.001). R-UTIs were associated with very poor graft survival and patient survival when compared with no UTI after a follow up of 5 years (hazard ratio [HR], 1.506; 95% confidence interval [CI], 1.233-1.840; P < 0.001 & HR, 1.529; 95% CI, 1.227-1.905; P = 0.001). R-UTIs were more likely to be associated with multi-drug resistant Gram-negative organisms (Klebsiella pneumonia or Escherichia coli) with resistance to nitrofurantoin (RR, 2.753; 95% CI, 1.257-6.032; P = 0.01) and carbapenem (RR, 2.064; 95% CI, 0.988-4.314; P = 0.05).

CONCLUSION

Compared to no UTI, R-UTIs were associated to worse graft and patient outcomes after a follow-up of 5 years, whereas NR-UTIs were associated with poor graft and patient outcomes in the long term.

Assessing the Influence of Urine pH on the Efficacy of Ciprofloxacin and Fosfomycin in Immunocompetent and Immunocompromised Murine Models of Escherichia coli and Klebsiella pneumoniae Infection in the Lower Urinary Tract

In vitro studies have suggested that acidic pH may reduce and increase the efficacy of ciprofloxacin and fosfomycin, respectively, when used to treat Escherichia coli and Klebsiella pneumoniae infections. We assessed the effects of acidic, neutral, and alkaline urine pH on the efficacy of optimized ciprofloxacin and fosfomycin dosages in UTI murine model of E. coli and K. pneumoniae. Immunocompetent and immunocompromised mice with adjusted urine pH were inoculated with E. coli and K. pneumoniae strains, and the efficacy was assessed based on the bacterial concentrations in tissues and fluids at 72 h, with respect to untreated controls. At acidic urine pH, both antimicrobials were effective, achieving similar reductions in E. coli concentrations in the kidneys in immunocompetent and immunocompromised mice and in K. pneumoniae in immunocompetent mice. At a neutral urine pH, both therapies reduced the presence of E. coli in the kidneys of immunocompetent mice. However, in immunocompromised mice, antimicrobials were ineffective at treating E. coli infection in the kidneys at a neutral urine pH and showed reduced efficacy against K. pneumoniae at both acidic and neutral urine pH. The results showed no correlation between urine pH and antimicrobial efficacy, suggesting that the reduced effectiveness is associated with the animals' immunocompetence status.

The Predictors and Risk Factors of 2-Year Rejection in Renal Transplant Patients: A Multicenter Case-Control Study

INTRODUCTION

Kidney transplantation is a definitive treatment for end-stage renal disease. It is associated with improved life expectancy and quality of life. One of the most common complications following kidney transplantation is graft rejection. To our knowledge, no previous study has identified rejection risk factors in kidney transplant recipients in Saudi Arabia. Therefore, this study aimed to determine the specific risk factors of graft rejection.

METHODS

A multicenter case-control study was conducted at four transplant centers in Saudi Arabia. All adult patients who underwent a renal transplant between January 1, 2015 and December 31, 2021 were screened for eligibility. Included patients were categorized into two groups (cases and control) based on the occurrence of biopsy-proven rejection within 2 years. The primary outcome was to determine the risk factors for rejection within the 2 years of transplant. Exact matching was utilized using a 1:4 ratio based on patients' age, gender, and transplant year.

RESULTS

Out of 1,320 screened renal transplant recipients, 816 patients were included. The overall prevalence of 2-year rejection was 13.9%. In bivariate analysis, deceased donor status, the presence of donor-specific antibody (DSA), intraoperative hypotension, Pseudomonas aeruginosa, Candida, and any infection within 2 years were linked with an increased risk of 2-year rejection. However, in the logistic regression analysis, the presence of DSA was identified as a significant risk for 2-year rejection (adjusted OR: 2.68; 95% CI: 1.10, 6.49, p = 0.03). Furthermore, blood infection, infected with Pseudomonas aeruginosa or BK virus within 2 years of transplant, were associated with higher odds of 2-year rejection (adjusted OR: 3.10; 95% CI: 1.48, 6.48, p = 0.003, adjusted OR: 3.23; 95% CI: 0.87, 11.97, p = 0.08 and adjusted OR: 2.76; 95% CI: 0.89, 8.48, p = 0.07, respectively).

CONCLUSION

Our findings emphasize the need for appropriate prevention and management of infections following kidney transplantation to avoid more serious problems, such as rejection, which could significantly raise the likelihood of allograft failure and probably death. Further studies with larger sample sizes are needed to investigate the impact of serum chloride levels prior to transplant and intraoperative hypotension on the risk of graft rejection and failure.

The Impact of Urinary Tract Infections in Kidney Transplant Recipients: A Six-Year Single-Center Experience

Background Urinary tract infections (UTIs) are the most common infections following kidney transplantation. Risk factors for UTIs in kidney transplant recipients include female gender, age, pre-transplant urinary tract abnormalities, diabetes, and recurrent UTIs. Infections of the bladder or urethra are termed lower UTIs, while those involving the kidneys or ureters are called upper UTIs. Methods We retrospectively screened our hospital information system to identify all patients who underwent kidney transplantation in the surgery department at King Abdulaziz Medical Center in Riyadh. A total of 553 records were ultimately included in the final analysis. Results A total of 553 patients were ultimately included in the analysis. More than half of the patients were males (62.4%), and 31.1% were aged between 45 and 60 years. Of these, 230 patients had a UTI, representing 41.59% of the sample. The most commonly reported causes were hypertensive nephrosclerosis (43.4%) and diabetic nephropathy (28.8%). The most frequently isolated causative agents were Escherichia coli (51.0%) and Klebsiella pneumoniae (21.8%). UTIs were significantly more prevalent among females, accounting for 73.6% of cases. Antibiotics were used in 86.5% of patients, with trimethoprim/sulfamethoxazole (65.8%) and ciprofloxacin (54.8%) being the most commonly prescribed. Conclusion About half of the patients in this study suffered from UTIs. E. coli and K. pneumoniae were the most commonly isolated organisms. Trimethoprim/sulfamethoxazole and ciprofloxacin were the most frequently prescribed antibiotics. A significant association was found between acquiring a UTI and being female (p < 0.001), as well as having pre-existing bladder dysfunction (p = 0.024).

Early Economic Assessment of Faecal Microbiota Transplantation for Patients with Urinary Tract Infections Caused by Multidrug-Resistant Organisms

INTRODUCTION

The use of faecal microbiota transplantation (FMT) to eradicate intestinal carriage of multidrug-resistant organisms (MDRO) has been described in case reports and small case series. Although few in numbers, these patients suffer from recurrent infections that may exacerbate both the patients' comorbidities and their healths. In the current study, we hypothesized that FMT for MDRO-related urinary tract infections (UTIs) reduces hospitalisations and associated costs.

METHODS

In a cohort of patients referred for FMT from 2015 to 2020, we selected all patients who had consecutively been referred for eradication of MRDO carriage with UTIs. An early economic assessment was performed to calculate hospital-related costs. The overall study cohort was registered at ClinicalTrials, study identifier NCT03712722.

RESULTS

We consecutively included five patients with UTIs caused by MDROs. Four of the patients were renal transplant recipients. Patients were followed for median 126 days (range 60-320), where the follow-up duration for each patient was aligned with the number of days from the first UTI to FMT. The median number of UTIs per patient dropped from 4 to 0. Investigating hospital costs, hospital admission days dropped by 87% and monthly hospital costs by 79%.

CONCLUSIONS

FMT was effective in reducing the occurrence of UTIs and mediated a marked reduction in hospital costs. We suggest that this strategy is cost-effective.

TRIAL REGISTRATION

ClinicalTrials, study identifier NCT03712722.

Unmet Needs in Complicated Urinary Tract Infections: Challenges, Recommendations, and Emerging Treatment Pathways

While urinary tract infections (UTIs) are one of the most common types of infections globally, the wide variety of presentations and of severity of disease can make it difficult to manage. The definition for uncomplicated UTIs (uUTIs) is generally regarded as UTIs in healthy, non-pregnant women whereas all other UTIs are considered complicated. There is, however, a lack of consensus definition of complicated UTIs (cUTIs), leading to global differences in management. In addition, the patients who develop complicated UTIs generally have other comorbidities that warrant more urgent intervention. One of the biggest challenges in treating cUTIs is the rise of antimicrobial resistance (AMR). While there have been recent drug approvals for new antibiotic to treat these resistant organisms, a multidisciplinary approach, including regulatory frameworks, provider education and public awareness campaigns, is crucial to limiting unnecessary treatments for asymptomatic bacteriuria (ASB) and uUTIs that can ultimately lead to more severe infections.

Frequency of Bacteremia and Urinary Tract Infection in Pediatric Renal Transplant Recipients

BACKGROUND

Our primary goal was to determine the frequency of bacteremia and urinary tract infections (UTI) in pediatric renal transplant recipients presenting with suspected infection within 2 years of transplant and to identify clinical and laboratory factors associated with bacteremia.

METHODS

We conducted a retrospective cross-sectional study for all pediatric ( < 18 years old) renal transplant recipients seen at 3 large children's hospitals from 2011 to 2018 for suspected infection within 2 years of transplant date, defined as pyrexia ( > 38°C) or a blood culture being ordered. Patients with primary immunodeficiencies, nontransplant immunosuppression, intestinal failure, and patients who had moved out of the local area were excluded. The primary outcome was bacteremia or UTI; secondary outcomes included pneumonia, bacterial or fungal meningitis, respiratory viral infections, and antibiotic resistance. The unit of analysis was the visit.

RESULTS

One hundred fifteen children had 267 visits for infection evaluation within 2 years of transplant. Bacteremia (with or without UTI) was diagnosed in 9/213 (4.2%) and UTIs in 63/189 (33.3%). Tachycardia and hypotension were present in 66.7% and 0% of visits with documented bacteremia, respectively. White blood cell (12,700 cells/mm 3 vs. 10,900 cells/mm 3 ; P = 0.43) and absolute neutrophil count (10,700 vs. 8200 cells/mm 3 ; P = 0.24) were no different in bacteremic and nonbacteremic patients. The absolute band count was higher in children with bacteremia (1900 vs. 600 cells/mm 3 ; P = 0.02). Among Gram-negative pathogens, antibiotic resistance was seen to 3rd (14.5%) and 4th (3.6%) generation cephalosporins, 12.7% to semisynthetic penicillins, and 3.6% to carbapenems.

CONCLUSIONS

Bacteremia or UTIs were diagnosed in one-quarter of all pediatric renal transplant recipients presenting with suspected infection within 2 years of transplant. Evaluations were highly variable, with one-third of visits not having urine cultures obtained. No single demographic, clinical or laboratory variable accurately identified patients with bacteremia, although combinations of findings may identify a high-risk population.

Effects of Bacterial Urinary Tract Infection on Clinical Outcome and Survival of Kidney Transplant Patients

BACKGROUND

There is no consensus on whether the development of urinary tract infections (UTIs) leads to high mortality or graft loss in kidney transplant patients. A high incidence of multidrug resistant (MDR) infections was observed worldwide and is associated with these complications. The aim of this study was to analyze the effects of UTIs on the clinical outcome and survival in kidney transplant patients.

METHODS

This retrospective study evaluated 601 kidney transplant patients who were categorized as follows: group 1 (G1) patients without a UTI, group 2 (G2) patients with a UTI, and group 3 (G3) recipients with a recurrent UTI. Patients were followed up for at least 1 year after transplantation. Graft survival, risk of graft loss, and risk of developing a UTI were analyzed by the Kaplan-Meier method, Cox regression, and logistic regression methods, respectively. Differences with P < .05 were considered statistically significant.

RESULTS

The proportion of rejection episodes was higher in G3 (32.35%) than in G1 (20.89%) and G2 (21.88%) (P < .001). The graft survival after the 10-year follow-up was better in G1 (73.29%) than in G3 (61.62%) (P = .019). UTI recurrent episodes increased the risk of graft loss >2.5-fold. Women and those who received a kidney from a deceased donor (DD) were at risk of at least 1 UTI event during follow-up. A greater proportion of MDR infections was observed in G3 than in G2 (P < .001).

CONCLUSIONS

The risk factors for developing a UTI were female sex, receiving a DD kidney, susceptibility to other infections, episodes of rejection, and delayed graft function. Moreover, a UTI, especially a recurrent UTI, was an important risk factor for allograft loss.

Urinary Tract Infections Caused by K. pneumoniae in Kidney Transplant Recipients – Epidemiology, Virulence and Antibiotic Resistance

Urinary tract infections are the most common complication in kidney transplant recipients, possibly resulting in the deterioration of a long-term kidney allograft function and an increased risk of recipient’s death. K. pneumoniae has emerged as one of the most prevalent etiologic agents in the context of recurrent urinary tract infections, especially with multidrug resistant strains. This paper discusses the epidemiology and risk factors associated with urinary tract infections in kidney transplant recipients, multi-drug resistance of K. pneumoniae (ESBL, KPC, NDM), treatment and pathogenesis of K. pneumoniae infections, and possible causes of recurrent UTIs. It also addresses the issue of colonization/becoming a carrier of K. pneumoniae in the gastrointestinal tract and asymptomatic bacteriuria in relation to a symptomatic UTI development and epidemiology.

Urinary Tract Infections in Kidney Transplant Recipients-Is There a Need for Antibiotic Stewardship?

(1) Background: Urinary tract infections (UTI) are the most common infections after kidney transplantation. Given the risk of urosepsis and the potential threat to the graft, the threshold for treating UTI and asymptomatic bacteriuria with broad spectrum antibiotics is low. Historically fluoroquinolones were prescription favorites for patients that underwent kidney transplantation (KT). After the recent recommendation to avoid them in these patients, however, alternative treatment strategies need to be investigated (2) Methods: We retrospectively analyzed the charts of 207 consecutive adult kidney transplantations that were performed at the department of General, Visceral and Transplantation Surgery of the University Hospital of Tuebingen between January 2015 and August 2020. All charts were screened for the diagnosis and treatment of asymptomatic bacteriuria (ASB) and urinary tract infections (UTI) and the patients' clinical characteristics and outcomes were evaluated. (3) Results: Of the 207 patients, 68 patients suffered from urinary tract infections. Patients who developed UTI had worse graft function at discharge (p = 0.024) and at the 12 months follow-up (p < 0.001). The most commonly prescribed antibiotics were Ciprofloxacin and Piperacillin/Tazobactam. To both, bacterial resistance was more common in the study cohort than in the control group. (4) Conclusions: Urinary tract infections appear to be linked to worse graft functions. Thus, prevention and treatment should be accompanied by antibiotic stewardship teams.

Recurrent Urinary Tract Infections and Asymptomatic Bacteriuria in Adults

Purpose of review

Our goal was to summarize recent evidence regarding recurrent urinary tract infections and asymptomatic bacteriuria in different adult populations.

Recent findings

Several research groups are focused on the description of resident bacterial flora in the bladder and urinary dysbiosis in the microbiome era. Even the definitions might change in light of these discoveries. However, the role of urinary microbiome and bacterial interference has still to be determined.

Summary

Systematic treatment of asymptomatic bacteriuria is not recommended and even classic indications such as asymptomatic bacteriuria in pregnant women are controversial. In fact, its treatment is associated with a higher probability of symptomatic UTI and a higher prevalence of antibiotic-resistant bacteria. Improving the diagnosis of asymptomatic bacteriuria and optimizing the management of recurrent urinary tract infections, especially through non-antibiotics measures, are needed in order to minimise antimicrobial resistance.

Managing recurrent urinary tract infections in kidney transplant recipients using smartphone assisted urinalysis test

BACKGROUND

Urinary tract infection is the most frequent infectious complication in allograft recipients with poor outcomes. The study aimed to assess the effect of self-testing urine dipsticks at home, with the assistance of smartphone technology, on the occurrence of urinary tract infection (UTI)-associated complications and frequency and length of hospital admissions.

METHOD

We performed a retrospective cohort study of kidney transplant recipients with a history of recurrent UTI who used a newly introduced smartphone-assisted dipsticks urinalysis test for self-monitoring. Participants self-administered the home urinalysis test with symptom onset. Antibiotics were prescribed if an infection was suspected, and home urinalysis was positive. The incidence of urinary infections, hospitalisations, and complications was evaluated before and during the home urinalysis period. Remote and face-to-face interactions with healthcare personnel were also assessed (cases acted as their controls).

RESULTS

Nineteen participants were included in the study. A total of 89.5% were females. Ninety home urinalysis tests were conducted over a mean period of 7 months. Sixty-one of these were pre-antibiotic. A total of 42.2% of all tests and 47.5% of the pre-antibiotic tests were positive. UTI-related hospitalisations were lower by 75% during the home urinalysis period; mean 1.26 (0.8-1.6) versus 0.32 (-0.01-0.6). The incidence of infection-related complications was also 65% lower; mean 1.52 (0.8-2.2) versus 0.52 (-0.2-1.2) during the same period. The number of face-to-face interactions was slightly lower; mean 1.9 (1.1-2.2) versus 1.7 (0.6-2.8), with more remote interactions; mean 6.0 (3.7-8.5) versus 10.4 (6.5-14.3), during smartphone urinalysis. Fifty per cent of antibiotic-treated UTI episodes had antibiotics within 24 h, rising to 82% within 48 h of a test.

CONCLUSION

Smartphone-assisted home urinalysis enabled remote management of UTI in a high-risk population. Outcomes point to a reduction in UTI complications and hospitalisations.

Asymptomatic bacteriuria and urinary tract infections in kidney transplant recipients

PURPOSE OF REVIEW

Urinary tract infection (UTI) is the most common infection in kidney transplant recipients (KTRs). Several elements increase the risk of UTI and/or modify its clinical presentation among KTRs (e.g. immunosuppressive therapy, kidney allograft denervation, and use of urinary catheters). Also, KTRs may have UTIs because of difficult-to-identify and/or difficult-to-treat organisms. We provide an overview of the current knowledge regarding bacterial UTIs in KTRs, with a focus on recent findings.

RECENT FINDINGS

There is accumulating evidence from clinical trials that screening for and treating asymptomatic bacteriuria is not beneficial in most KTRs (i.e. those who are ≥1-2 months posttransplant and do not have a urinary catheter). These patients have a point-prevalence of asymptomatic bacteriuria of only 3% and treating asymptomatic bacteriuria probably does not improve their outcomes. There is no clinical trial evidence to guide the management of symptomatic UTI in KTRs. Several important clinical questions remain unanswered, especially regarding the management of posttransplant pyelonephritis and the prevention of UTI in KTRs.

SUMMARY

Despite its frequency and associated morbidity, UTI after kidney transplantation is an understudied infection. In an era of increasing antimicrobial resistance and limited resources, further research is needed to ensure optimal use of antimicrobials in KTRs with UTI.

Overview on urinary tract infection, bacterial agents, and antibiotic resistance pattern in renal transplant recipients

Background:

Urinary tract infection (UTI) is a mainly common infection in kidney transplant recipients. This study decided to investigate UTI, bacterial agents, and antibiotic resistance pattern in kidney transplant recipients from Iran.

Materials and Methods:

Search process was conducted for UTI, bacterial agents, and antibiotic resistance pattern in kidney transplant recipients from Iran via electronic databases (Scopus, PubMed, Web of Science, etc.,) with Mesh terms in either Persian and English languages without limited time to May 31, 2020. Data were analyzed by comprehensive meta-analysis software.

Results:

The combined prevalence of UTI in renal transplant recipients was reported by 31.1%. The combined prevalence of Gram-negative bacteria was 69%. The most common pathogens among Gram negatives were E. coli followed by Klebsiella pneumoniae with frequency 43.4% and 13%, respectively. Subgroup analysis for Gram-positive bacteria showed the combined prevalence of 31%. The most common microorganism among Gram positives belonged to coagulase-negative Staphylococci and Enterococci with a prevalence of 10.2% and 9%, respectively. Subgroup meta-analysis of antibiotic resistance for Gram-negative showed the most resistance to cephalexin followed by carbenicillin with a prevalence of 89.1% and 87.3%, respectively.

Conclusion:

Our review showed a noticeable rate of UTI (31.1%) among renal transplant recipients in Iran and a high prevalence of Gram-negative (69%) and Gram-positive (13%) microorganisms. A high resistance rate was seen against almost all antibiotics used for the treatment of UTI. Therefore, empirical prescription of antibiotics should be avoided, and it should be based on data obtained from antibiogram tests.

Causes of Renal Allograft Injury in Recipients With Normal Donor-derived Cell-free DNA

Background.

Donor-derived cell-free DNA (dd-cfDNA) is a noninvasive biomarker for the early detection of organ transplant rejection and other causes of graft injury. For nonrejection renal injuries, there is little information about the performance characteristics of this biomarker. We highlight some of the possible causes of kidney injury that may arise in patients with normal dd-cfDNA levels.

Methods.

We performed a retrospective analysis of solitary renal transplant cases between January 2017 and November 2019. Those who had an abnormal laboratory or pathological finding within 1 mo of a normal dd-cfDNA test were selected. Subgroups were stratified for those who had normal or abnormal/rising serum creatinine, and differences between the groups were analyzed.

Results.

Of 414 individuals who received a kidney transplant, 24 (7.5%) had a total of 41 normal dd-cfDNA values and 51 abnormal laboratory tests or histologic findings. The most common graft-injuring event was BK virus viremia (24 of 51). Other abnormal findings included urinary traction infections (n = 4), CMV viremia (n = 4), and biopsies demonstrating antibody-mediated rejection (AMR) (n = 2), T cell–mediated rejection (n = 1), focal segmental glomerulosclerosis (n = 2), nondonor-specific antibody chronic AMR (n = 1), and interstitial fibrosis and tubular atrophy (n = 7). Subgroup analysis of those with normal dd-cfDNA and normal/stable versus abnormal/rising creatinine showed that BK virus viremia was the most common abnormal finding in both groups at 53% and 38% respectively. On biopsy, 1 case of acute T cell–mediated rejection (1B and 2B) was seen with normal/stable creatinine, whereas 1 of nonspecific C4d focally positive and 1 of nondonor-specific antibody AMR were seen with abnormal/rising creatinine.

Conclusions.

Low levels of serum dd-cfDNA do not preclude detection of active graft-injuring events and that subclinical injuries may be developing. Context is important in the interpretation of dd-cfDNA, so renal biopsy remains a part of the diagnostic pathway for allograft dysfunction and maintenance of allograft health.

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.

The urinary microbiome shows different bacterial genera in renal transplant recipients and non-transplant patients at time of acute kidney injury - a pilot study

Background

In the past urine was considered sterile. Through the introduction of next generation sequencing, it has become clear that a urinary microbiome exists. Acute kidney injury (AKI) represents a major threat to kidney transplant recipients. Remarkable changes in the urinary metabolome occur during AKI, which may influence the urinary microbiome. To our knowledge, this is the first study that examines the urinary microbiome in renal transplant recipients (RTX) and non-transplant recipients (nRTX) at time of AKI.

Methods

In this cross-sectional pilot-study the urinary microbiome of 21 RTX and 9 nRTX with AKI was examined. Clean catch morning urine samples were obtained from all patients on the first day of AKI diagnosis. AKI was defined according to KDIGO guidelines. Urinary microbiota and the urinary metabolome during AKI were assessed in one patient. 16S rRNA sequencing was performed. Sequences were processed using UPARSE-pipeline for operational taxonomic units (OTU) and taxon finding.

Results

We successfully extracted and sequenced bacterial DNA from 100% of the urine samples. All 30 patients revealed at least 106,138 reads. 319 OTU and 211 different genera were identified. The microbiotic diversity richness in the RTX group was no different from the nRTX group. Eighteen genera were solely present in nRTX and 7 in RTX.

Conclusions

The urinary microbiome at time of AKI showed different bacterial genera in RTX compared to nRTX. The nRTX group exhibited no different diversity to the RTX group. Irrespective of the status of a previous renal transplantation, the urinary microbiome comprised > 210 different genera. An intraindividual change in microbiota diversity and richness was observed in one study patient during recovery from AKI.

Acute Kidney Injury in Hospitalized Kidney Transplant Recipients

BACKGROUND

Acute kidney injury (AKI) is a main cause of morbidity, hospitalization, and hospital readmission in kidney transplant recipients. We aimed to determine AKI incidence and risk factors following kidney transplant to assess outcomes such as renal function and graft loss after AKI.

METHODS

We conducted a retrospective cohort study with hospitalized kidney transplant recipients during 2016 to 2017. Clinical data of 179 patients were reviewed. The primary outcome was AKI incidence and risk factors. To determine AKI occurrence, we based it on creatinine criteria from Acute Kidney Injury Network classification.

RESULTS

We documented a total of 179 hospital admissions; AKI was diagnosed in 104 patients (58.1%). Recipients with higher baseline serum creatinine (odds ratio, 2.6; confidence interval [CI], 1.5-4.5; P < .001) and hospital admission because of infections (odds ratio, 2.4; CI, 1.1-5.2; P = .020) were more likely to experience AKI. A total of 19 recipients (10.6%) had graft loss with a significant AKI association (P = .003) at 12 months after admission. Intensive care unit length of stay (P = .63) and hospital stay (P = .55) were not different in patients with AKI compared with the control group.

CONCLUSIONS

As a main clinical finding, we concluded that infections and higher serum creatinine baseline level were associated with the development of AKI.