Renal allograft injury is associated with urinary tract infection caused by Escherichia coli bearing adherence factors

Prevalence and Predictive Factors of Urinary Tract Infection in Kidney Transplant Recipients: A 10-Year Study

OBJECTIVES

Urinary tract infections are the main infectious complications among kidney transplant recipients and are considered as a potential risk factor for poor graft outcomes. However, the risk factors of urinary tract infections are controversial. The purpose of our study was to estimate the incidence and predisposing factors of urinary tract infections in patients undergoing kidney transplant in our teaching hospital of Sahloul, Tunisia.

MATERIALS AND METHODS

We retrospectively analyzed the charts of 141 consecutive adult kidney transplants that were performed at the Department of Nephrology, University Hospital of Sahloul, Tunisia, between January 2007 and April 2016.

RESULTS

Of 141 patients, 72 (51.1%) had urinary tract infections after kidney transplant. Mean age was 32.54 ± 12.1 years; 47.6% were male patients, and 52.4% were female patients. The average time between transplant and early urinary tract infections was 11 days (range, 1-30 days). Among our patient group, 87.8% of urinary tract infections occurred within the first 6 months posttransplant. We collected 205 episodes of urinary tract infections: 66.3% were asymptomatic bacteriuria, 10.2% acute cystitis, and 23.4% pyelonephritis. The estimated risk factors for urinary tract infection included only female sex (P < .05); older age (P = .32), longer duration of catheter (P = .34), and high body mass index (P = .46) were not correlated with urinary tract infection.

CONCLUSIONS

Despite preventive measures, urinary tract infections remain an important cause of morbidity among kidney transplant recipients. In fact, more than half of kidney transplant recipients had at least 1 urinary tract infection after surgery. Female sex was statistically associated with higher risk of urinary tract infection.

Outcomes of asymptomatic histologic pyelonephritis of kidney transplant

BACKGROUND

Urinary Tract Infections are the most common post-transplant infection and can have varied presentations. This study aimed to describe the outcomes of kidney transplant recipients with asymptomatic histologic pyelonephritis on allograft biopsy. Histologic Pyelonephritis was defined as neutrophil cast or neutrophilic tubulitis, interstitial infiltrates with predominant neutrophils, and no evidence of rejection or glomerulonephritis on biopsy.

METHODS

The study included 123 kidney transplant recipients, of whom 95 underwent protocol biopsies, and 28 had biopsies for elevated creatinine within the first 2 years of a kidney transplant.

RESULTS

The mean age of the cohort was 55.3 years, with 52% females and 78% deceased donor transplants. The risk factors for asymptomatic histologic pyelonephritis were recipient female sex (OR 1.89, 1.3-2.7, diabetes mellitus (OR 2.479, 1.687-3.645), and deceased donation (OR 1.69, 1.098-2.63). The incidence of asymptomatic pyelonephritis on protocol biopsy was 1.7%, with 52% having positive urine cultures and Escherichia coli being the most common bacteria. Subjects with asymptomatic pyelonephritis had inferior graft survival compared to the matched cohort HR 1.88 (1.06-3.35), p = .0281. In addition, of these 123 subjects, 68 (55%) subsequently developed pyelonephritis, and 34 subjects had pyelonephritis within 6 months after this episode. Subjects with recurrent infections exhibited lower survival HR 2.86 (1.36-6.02) and a trend toward higher rejection risk.

CONCLUSION

Asymptomatic histologic pyelonephritis can occur in kidney transplant recipients and is associated with inferior graft survival.

Aptitude of Uropathogenic Escherichia coli in Renal Transplant Recipients: A Comprehensive Review on Characteristic Features, and Production of Extended Spectrum β-Lactamase

Urinary tract infection is the most common infection in almost half of the renal transplant patients. The development of UTI in these patients may progress to bacteremia, acute T cell-mediated rejection, impaired allograft function, or allograft loss, along with the increased risk of hospitalization and death. Among various pathogens implicated, Uropathogenic E. coli (UPEC), especially sequence type 131 (ST131), is the most virulent and multidrug-resistant pathogen. High antimicrobial resistance to most β-lactam antibiotics, mediated by extended spectrum β-lactamases (ESBLs) produced by UPEC, is a challenge in the clinical management of UTIs in kidney transplant recipients. Indeed, multidrug resistance to β-lactam antibiotics is a direct consequence of ESBL production. Resistance to other antibiotics such as aminoglycosides, fluoroquinolones, and trimethoprim-sulphamethoxazole has also been reported in ESBLs-producing UPEC, which reduces the therapeutic options, rising healthcare-associated costs and subsequently leads to renal failure or even graft loss. In this review, we aimed to discuss the post-transplant risk factors of UTI, UPEC virulence factors (VF), and the related factors including quorum sensing, and stress resistance genes. Furthermore, we searched for the current treatment strategies and some of the alternate approaches proposed as therapeutic options that may affirm the treatment of ESBL-producing UPEC.

Urinary Tract Infection 1 Year After Kidney Transplant: Effect on Kidney Transplant Outcomes

OBJECTIVES

Transplant is the gold standard treatment for end-stage renal disease, and yet infectious complications frequently arise in kidney recipients in the context of immunosuppression therapy, with urinary tract infection being the most common. We aimed to assess the prevalence of posttransplant urinary tract infections in kidney transplant recipients and assess the effects on kidney allograft and overall patient outcomes.

MATERIAL AND METHODS

We performed a retrospective analysis of data from State University of New York Upstate University Hospital from January 2016 to November 2022 to assess transplant outcomes in patients who underwent a kidney transplant at our center and met the inclusion criteria.

RESULTS

There were 507 renal allograft recipients who met our inclusion criteria and were assessed for the incidence of urinary tract infection within the first year after transplant. Urinary tract infection was recurrent in 113 transplant recipients (55.6%) within the first year, and 118 (58.1%) were on prophylactic antibiotics at urinary tract infection diagnosis. We observed no relation between recurrence of urinary tract infection and use of prophylactic antibiotics (P = .21). Overall allograft survival rate was 92.1% in the urinary tract infection group and 96.7% in the group without urinary tract infection, which was significantly different (P = .02). Urinary tract infection significantly affected allograft survival (hazard ratio, 3.51; 95% CI, 1.49-8.23; P = .004). Overall patient survival rates were 86.7% and 91.4% in the groups with and without urinary tract infection, respectively (P = .08).

CONCLUSIONS

We determined that allograft survival was significantly greater in the group without urinary tract infection versus the urinary tract infection group. We found no relation between urinary tract infection recurrence and prophylactic antibiotics. We also found that overall patient survival was not significantly different in the group with urinary tract infection versus the group without urinary tract infection.

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.

Recurrent Urinary Tract Infection in Living Donor Renal Transplant Recipients and the Role of Behavioral Education Program in Management: A Single-Center Experience

BACKGROUND

Urinary tract infections (UTIs) are the most prevalent type of kidney transplant (KT) recipients. We aimed to investigate the incidence, causes, and clinical impact of early recurrent UTI post-living donor KT and to examine the role of behavioral education program in management.

METHODS

This retrospective cohort chart-review study included all KT recipients with recurrent UTI necessitating hospital admission between September 2017 and August 2021. All patients with recurrent UTI were subjected to behavioral education for a month.

RESULTS

UTI was found in 14 of 145 patients (9.6%), with recurrent UTI in 11 (7.6%). A total of 93% of UTIs occurred during the first 6 months post-transplant and represented 52% of KT readmissions during the same period. A total of 64.3% of patients were older than 50 years. The mean (SD) length of hospital stay was 5 (2.5) days, with an equal incidence in both sexes. The most common bacterial isolates in early recurrent UTI were Escherichia coli in 80.9%. Both Extended-spectrum beta-lactamases and multidrug-resistant organisms (resistance in ≥3 drugs) were seen in 82.4% of isolates. Furthermore, the most effective antibiotic was meropenem, with 86.7% effectiveness. A total of 65% of UTIs were managed with a single antibacterial course. A total of 64.3% of patients were older than 50 years. In patients who developed UTI, the mean (SD) serum creatinine was 1.31 (0.52) mg/dL, with a mean increase in serum creatinine of 0.19 mg/dL on having the episodes; at 1 year post-transplant, serum creatinine declined to 1.23 (0.43) mg/dL. Four patients (36%) had no recurrence of UTI after behavioral education.

CONCLUSIONS

The multidrug-resistant bacterial isolates account for 82.4% of the UTIs. Therefore, antibiotic prescription should follow the antimicrobial stewardship guidelines. Behavioral education significantly reduced the incidence of recurrent UTI.

Impact of Late and Recurrent Acute Graft Pyelonephritis on Long-Term Kidney Graft Outcomes

Background

While Urinary tract infections are the most common infections in kidney transplant recipients, the impact of late acute graft pyelonephritis (AGPN) on graft outcomes remains unknown. Our study was performed to more precisely evaluate the long-term impact of AGPN.

Methods

We included 9052 kidney and combined kidney-pancreas recipients who underwent transplantation between 2008 and 2018 from a French multicenter cohort. The relationships between AGPN and patient and graft survival were analyzed with a time-dependent multivariate Cox model.

Results

The cumulative incidence of AGPN was 20.9%. A first episode of early AGPN is associated with a non-significant increase in the risk of graft failure (hazard ratio [HR], 1.27; 95% confidence interval [95% CI], 0.90 to 1.79). Though, cumulative number of AGPN episodes (HR = 1.51; 95% CI, 0.89 to 2.57 for two episodes and HR = 2.08; 95% CI, 1.17 to 3.69 for three or more episodes) is associated with an increased risk of graft failure. In contrast, when the first episode of AGPN occurred late (i.e., 6 months post transplantation), the risk of graft failure is significantly increased (HR = 2.25; 95% CI, 1.65 to 3.07), and this risk remains relatively stable with the recurrence of late AGPN episodes. The onset of late AGPN were also associated with a higher risk of patient death.

Conclusion

This analysis shows that late AGPN and recurrent AGPN are both risk factors for a poor long-term graft outcome and mortality. Late AGPN should not be considered benign infections in post-transplantation follow-up.

Emergency Department Utilization and Serious Bacterial Infection Rates in Children With Renal Transplants

OBJECTIVES

Emergency department (ED) visits by children with solid organ transplants have increased significantly. Our objectives were to describe the common complaints, diagnosis, types, and rates of serious bacterial infection (SBI) in children with renal transplant (RT) who present to the hospital.

METHODS

We conducted a retrospective study from 2012 to 2016 of RT children up to 18 years who presented to the ED or were directly admitted. We excluded patients who presented for a procedure. We collected demographics, transplant type, immunosuppressive data, chief complaints, diagnostic testing with results, interventions performed, and final diagnosis.

RESULTS

We analyzed 131 visits in 29 patients during the study period. Most common chief complaints were infectious (34.4%) and gastrointestinal (26%). Infection was proven in 42.0% of visits with only 3.1% being organ rejection. Serious bacterial infection was diagnosed in 34 visits (26.0%) with urinary tract infection (UTI) being the most common (20.6%). Of the 33 visits for fever, SBI occurred in 16 (48.5%) patients with the most common SBI being UTI 10 (30.3%). Bacteremia occurred in 1 patient and hypotension in 4 patients. Antibiotic administration was the most common intervention performed (78; 59.5%). Significant interventions were uncommon (2 patients). Logistic regression revealed no factors to be associated with SBI.

CONCLUSIONS

Our cohort of children with RT presented most commonly with infections to the hospital with UTI being the most common SBI. Bacteremia and significant interventions were rare. Future studies are needed to identify subgroups of low-risk pediatric RT patients who can possibly be safely discharged home from the ED.

Host and microbial factors in kidney transplant recipients with Escherichia coli acute pyelonephritis or asymptomatic bacteriuria: a prospective study using whole-genome sequencing

BACKGROUND

Urinary tract infection is the most common infection among kidney transplant recipients (KTRs). Many transplant physicians fear that host compromise will allow low-virulence strains to cause pyelonephritis in KTRs, so they often treat asymptomatic bacteriuria with antibiotics. Identification of the host/microbe factors that determine the clinical presentation (i.e. pyelonephritis versus asymptomatic bacteriuria) once an Escherichia coli strain enters a KTRs bladder could inform management decisions.

METHODS

We prospectively collected all E. coli isolates causing either pyelonephritis or asymptomatic bacteriuria in KTRs at our institution (December 2012-June 2015). Whole-genome sequencing was used to assess bacterial characteristics (carriage of 48 virulence genes and phylogenetic and clonal background). Host parameters were also collected.

RESULTS

We analysed 72 bacteriuria episodes in 54 KTRs (53 pyelonephritis, 19 asymptomatic bacteriuria). The pyelonephritis and asymptomatic bacteriuria isolates exhibited a similar total virulence gene count per isolate [median 18 (range 5-33) and 18 (5-30), respectively; P = 0.57] and for individual virulence genes differed significantly only for the prevalence of the pap operon (pyelonephritis 39%,versus asymptomatic bacteriuria 0%; P = 0.002). No other significant between-group differences were apparent for 86 other bacterial and host variables.

CONCLUSIONS

Our findings suggest that bacterial adherence plays a role in the pathogenesis of pyelonephritis in KTRs despite significantly altered host urinary tract anatomy and weakened immunity. Whether KTRs might benefit from targeted therapies (e.g. vaccination or inhibitors of fimbrial adhesion) has yet to be studied.

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.

Phenotypic and Genotypic Characterization of Escherichia coli Causing Urinary Tract Infections in Kidney-Transplanted Patients

Urinary tract infection (UTI), frequently caused by uropathogenic Escherichia coli (UPEC), is the most common infection after kidney transplantation (KTx). Untreated, it can lead to urosepsis and impairment of the graft function. We questioned whether the UPEC isolated from KTx patients differed from the UPEC of non-KTx patients. Therefore, we determined the genome sequences of 182 UPEC isolates from KTx and control patients in a large German university clinic and pheno- and genotypically compared these two isolated groups. Resistance to the β-lactams, trimethoprim or trimethoprim/sulfamethoxazole was significantly higher among UPEC from KTx than from control patients, whereas both the isolated groups were highly susceptible to fosfomycin. Accordingly, the gene content conferring resistance to β-lactams or trimethoprim, but also to aminoglycosides, was significantly higher in KTx than in control UPEC isolates. E. coli isolates from KTx patients more frequently presented with uncommon UPEC phylogroups expressing higher numbers of plasmid replicons, but interestingly, less UPEC virulence-associated genes than the control group. We conclude that there is no defining subset of virulence traits for UPEC from KTx patients. The clinical history and immunocompromised status of KTx patients enables E. coli strains with low uropathogenic potential, but with increased antibiotic resistance to cause UTIs.

Urinary tract infections in solid organ transplant recipients: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of urinary tract infections (UTI) in solid organ transplantation, focusing on kidney transplant (KT) recipients. KT recipients have unique risk factors for UTI, including indwelling stents and surgical manipulation of the genitourinary tract. KT recipients experience multi-drug antibiotic-resistant infections-UTI prevention and management strategies must consider risks of antimicrobial resistance. Non-antimicrobial prevention strategies for UTI in KT recipients are reviewed. It is important to recognize that some renal transplant recipients with UTI may primarily present with fever, malaise, leukocytosis, or a non-specific sepsis syndrome without symptoms localized to the urinary tract. However, asymptomatic bacteriuria (AB) must be distinguished from UTI because AB is not necessarily a disease state. Accumulating data indicate that there are no benefits of antibiotics for treatment of AB in KT recipients more than 2 months after post-transplant. Further research is needed on management of AB in the early (<2 months) post-transplant period, prophylaxis for UTI in this era of antibiotic resistance, recurrent UTI, non-antimicrobial prevention of UTI, and uropathogens identified in donor urine and/or preservative fluid cultures.

Calcineurin inhibitor Tacrolimus impairs host immune response against urinary tract infection

Calcineurin inhibitor Tacrolimus, is a potent immunosuppressive drug widely used in order to prevent acute graft rejection. Urinary tract infection (UTI) is the most frequent infectious complication in renal transplant patients and long-term use of Tacrolimus might be involved in higher susceptibility to bacterial infections. It remains largely unknown how Tacrolimus affects the host innate immune response against lower and upper UTI. To address this issue, we used experimental UTI model by intravesical inoculation of uropathogenic E.coli in female wild-type mice pre-treated with Tacrolimus or solvent (CTR). We found that Tacrolimus pre-treated mice displayed higher bacterial loads (cystitis, pyelonephritis and bacteremia) than CTR mice. Granulocytes from Tacrolimus pre-treated mice phagocytized less E. coli, released less MPO and expressed decreased levels of CXCR2 receptor upon infection. Moreover, Tacrolimus reduced TLR5 expression in bladder macrophages during UTI. This immunosuppressive state can be explained by the upregulation of TLR-signaling negative regulators (A20, ATF3, IRAK-M and SOCS1) and parallel downregulation of TLR5 as observed in Tacrolimus treated granulocytes and macrophages. We conclude that Tacrolimus impairs host innate immune responses against UTI.

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.

[Molecular epidemiology and kinetics of early Escherichia coli urinary tract infections in kidney transplant recipients]

BACKGROUND

Escherichia coli strains causing Urinary Tract Infections (UTI) have a fecal origin.

METHODS

A fecal sample was collected before Kidney Transplantation (KT) and concomitantly with urine at each of the 15 E. coli UTIs which occurred in 11 KT recipients. Unique E. coli strains were identified among 25 isolates per feces and 5 isolates per urinary sample by random amplification of polymorphic DNA. Phylogenetic group (which is correlated to virulence in the E. coli species) was determined for each E. coli strain by a PCR based method.

RESULTS

Forty-three unique fecal strains and 14 unique urinary strains were identified among 650 fecal isolates and 75 urinary isolates. Urinary strains frequently (55% of the cases) belonged to a phylogroup usually not linked to virulence. They were detected in the feces collected concomitantly in 60% of the cases. Urinary strains belonging to a phylogroup usually linked to virulence were more frequently dominant in the feces (100%) than urinary strains belonging to a non-pathogenic phylogroup (42%; P<0.05). Vesical catheter was a facilitating factor only for urinary strains belonging to non-pathogenic phylogroups. Thirty-three percent of the fecal strains were persisting in two consecutive fecal samples and 62% were detected for the first time at the UTI. Numerous pathway lead to UTIs: from a unique, virulent and persisting strain to a non-virulent recently acquired strain facilitated by a vesical catheter.

CONCLUSION

Our work shows the diversity of host-microbial interactions which precede extra-intestinal virulence.

Population Phylogenomics of Extraintestinal Pathogenic Escherichia coli

The emergence of genomics over the last 10 years has provided new insights into the evolution and virulence of extraintestinal Escherichia coli. By combining population genetics and phylogenetic approaches to analyze whole-genome sequences, it became possible to link genomic features to specific phenotypes, such as the ability to cause urinary tract infections. An E. coli chromosome can vary extensively in length, ranging from 4.3 to 6.2 Mb, encoding 4,084 to 6,453 proteins. This huge diversity is structured as a set of less than 2,000 genes (core genome) that are conserved between all the strains and a set of variable genes. Based on the core genome, the history of the species can be reliably reconstructed, revealing the recent emergence of phylogenetic groups A and B1 and the more ancient groups B2, F, and D. Urovirulence is most often observed in B2/F/D group strains and is a multigenic process involving numerous combinations of genes and specific alleles with epistatic interactions, all leading down multiple evolutionary paths. The genes involved mainly code for adhesins, toxins, iron capture systems, and protectins, as well as metabolic pathways and mutation-rate-control systems. However, the barrier between commensal and uropathogenic E. coli strains is difficult to draw as the factors that are responsible for virulence have probably also been selected to allow survival of E. coli as a commensal in the intestinal tract. Genomic studies have also demonstrated that infections are not the result of a unique and stable isolate, but rather often involve several isolates with variable levels of diversity that dynamically changes over time.

Minimizing the Number of Urological Complications After Kidney Transplant: A Comparative Study of Two Types of External Ureteral Stents

OBJECTIVES

The aim of this study was to evaluate the effects of 2 types of external ureteral stents on the number of urological complications after kidney transplant.

MATERIALS AND METHODS

Data were retrospectively collected from 366 consecutive transplants performed between January 2013 and January 2015 in our hospital, in which an external ureteral stent was placed during surgery and removed after 9 days. Urological complications were defined as urinary leakage or ureteral stenosis requiring percutaneous nephrostomy placement.

RESULTS

A total of 197 patients received a straight stent with 2 larger side holes (type A; 8F "Covidien" tube; Covidien, Dublin, Ireland) and 169 patients received a single J stent with 7 smaller side holes (type B; 7F "Teleflex" single J stent; Teleflex Medical, Athlone, Ireland). We found a significantly higher number of percutaneous nephrostomy placements with type A stents, with 34 (17%) versus 16 (9%) in type B (P = .030). Reason for percutaneous nephrostomy placement, occurrence of stent dysfunction, and need for early removal (< 8 days) were equal in both groups (P = .397), whereas incidence of rejection and urinary tract infection were higher in type B stent group. Patient and graft survival did not differ between the groups.

CONCLUSIONS

Use of the type B stent was associated with less urological complications compared with the type A stent.

The Impact of Infection on Chronic Allograft Dysfunction and Allograft Survival After Solid Organ Transplantation

Infectious diseases after solid organ transplantation (SOT) are a significant cause of morbidity and reduced allograft and patient survival; however, the influence of infection on the development of chronic allograft dysfunction has not been completely delineated. Some viral infections appear to affect allograft function by both inducing direct tissue damage and immunologically related injury, including acute rejection. In particular, this has been observed for cytomegalovirus (CMV) infection in all SOT recipients and for BK virus infection in kidney transplant recipients, for community-acquired respiratory viruses in lung transplant recipients, and for hepatitis C virus in liver transplant recipients. The impact of bacterial and fungal infections is less clear, but bacterial urinary tract infections and respiratory tract colonization by Pseudomonas aeruginosa and Aspergillus spp appear to be correlated with higher rates of chronic allograft dysfunction in kidney and lung transplant recipients, respectively. Evidence supports the beneficial effects of the use of antiviral prophylaxis for CMV in improving allograft function and survival in SOT recipients. Nevertheless, there is still a need for prospective interventional trials assessing the potential effects of preventive and therapeutic strategies against bacterial and fungal infection for reducing or delaying the development of chronic allograft dysfunction.

Pathogenesis of human diffusely adhering Escherichia coli expressing Afa/Dr adhesins (Afa/Dr DAEC): current insights and future challenges

The pathogenicity and clinical pertinence of diffusely adhering Escherichia coli expressing the Afa/Dr adhesins (Afa/Dr DAEC) in urinary tract infections (UTIs) and pregnancy complications are well established. In contrast, the implication of intestinal Afa/Dr DAEC in diarrhea is still under debate. These strains are age dependently involved in diarrhea in children, are apparently not involved in diarrhea in adults, and can also be asymptomatic intestinal microbiota strains in children and adult. This comprehensive review analyzes the epidemiology and diagnosis and highlights recent progress which has improved the understanding of Afa/Dr DAEC pathogenesis. Here, I summarize the roles of Afa/Dr DAEC virulence factors, including Afa/Dr adhesins, flagella, Sat toxin, and pks island products, in the development of specific mechanisms of pathogenicity. In intestinal epithelial polarized cells, the Afa/Dr adhesins trigger cell membrane receptor clustering and activation of the linked cell signaling pathways, promote structural and functional cell lesions and injuries in intestinal barrier, induce proinflammatory responses, create angiogenesis, instigate epithelial-mesenchymal transition-like events, and lead to pks-dependent DNA damage. UTI-associated Afa/Dr DAEC strains, following adhesin-membrane receptor cell interactions and activation of associated lipid raft-dependent cell signaling pathways, internalize in a microtubule-dependent manner within urinary tract epithelial cells, develop a particular intracellular lifestyle, and trigger a toxin-dependent cell detachment. In response to Afa/Dr DAEC infection, the host epithelial cells generate antibacterial defense responses. Finally, I discuss a hypothetical role of intestinal Afa/Dr DAEC strains that can act as "silent pathogens" with the capacity to emerge as "pathobionts" for the development of inflammatory bowel disease and intestinal carcinogenesis.

Management of urinary tract infection in solid organ transplant recipients: Consensus statement of the Group for the Study of Infection in Transplant Recipients (GESITRA) of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC) and the Spanish Network for Research in Infectious Diseases (REIPI)

BACKGROUND

Urinary tract infections (UTIs) are one of the most common infections in solid organ transplant (SOT) recipients.

METHODS

Experienced SOT researchers and clinicians have developed and implemented this consensus document in support of the optimal management of these patients. A systematic review was conducted, and evidence levels based on the available literature are given for each recommendation. This article was written in accordance with international recommendations on consensus statements and the recommendations of the Appraisal of Guidelines for Research and Evaluation II (AGREE II).

RESULTS

Recommendations are provided on the management of asymptomatic bacteriuria, and prophylaxis and treatment of UTI in SOT recipients. The diagnostic-therapeutic management of recurrent UTI and the role of infection in kidney graft rejection or dysfunction are reviewed. Finally, recommendations on antimicrobials and immunosuppressant interactions are also included.

CONCLUSIONS

The latest scientific information on UTI in SOT is incorporated in this consensus document.

Impact of urinary tract infection on allograft function after kidney transplantation

OBJECTIVES

Urinary tract infection (UTI) is the most common infectious complication after kidney transplantation. We aim to determine its impact on allograft function as indicated by several measures such as iothalamate glomerular filtration rate (iGFR), estimated glomerular filtration rate (eGFR), and creatinine value.

METHODS

We performed a single-center retrospective cohort study to determine the impact of UTI on kidney allograft outcome.

RESULTS

The study population consisted of 301 kidney transplant recipients; 84% were living donor transplants. One hundred and one patients (34%) developed at least one episode of UTI and the incidence of UTI during the first year after transplantation was 25%. At the end of the follow-up, the iGFR was lower among patients who had developed at least one UTI (p = 0.044). However, eGFR and creatinine values were not significantly different between UTI and non-UTI groups.

CONCLUSION

When kidney function was measured by eGFR and creatinine, there was no significant difference in allograft function between kidney recipients with or without UTI. However, when kidney function was measured by nuclear studies, there was a tendency toward impairment in allograft function among patients who developed atleast one UTI after transplantation.

Extended-spectrum-beta-lactamase producing bacteria related urinary tract infection in renal transplant recipients and effect on allograft function

Background

Urinary tract infection (UTI) is a well-recognized early complication in renal transplant recipients (RTR) and can have significant bearing on their outcome. The recent rise in incidence of extended spectrum beta lactamase (ESBL) producing bacteria causing UTI among RTR poses new and significant challenges in terms of management and outcome. Our aim is to analyze the effect of ESBL producing bacteria causing UTI in these patients and its impact on allograft function.

Methods

We reviewed the medical records of 147 RTR who were followed at a tertiary care hospital affiliated transplant center between January 2007 and May 2013 and noted five RTR who developed episodes of ESBL producing bacteria related UTI during follow up. Multiple patient characteristics including demographics, immunosuppression, recurrences, allograft function and outcome were analyzed.

Results

Five patients (3.4%) out of 147 had ESBL producing bacteria related UTI. We found all patients to be above 60 years of age, with three out of five being females, and all five patients had diabetes mellitus. We identified a total of 37 episodes of UTI among these five patients during this period. Two of these patients had elevated creatinine values during the episodes of UTI and three of them developed bacteremia. Of the five patients, four of them had a favorable outcome except for one patient who developed persistent allograft dysfunction.

Conclusion

RTR are at a higher risk for developing ESBL producing bacteria associated UTI. Early diagnosis along with appropriate and judicious use of antibiotics will ensure long term success in allograft and patient outcome.

A subset of two adherence systems, acute pro-inflammatory pap genes and invasion coding dra, fim, or sfa, increases the risk of Escherichia coli translocation to the bloodstream

An analysis of the phylogenetic distribution and virulence genes of Escherichia coli isolates which predispose this bacteria to translocate from the urinary tract to the bloodstream is presented. One-dimensional analysis indicated that the occurrence of P fimbriae and α-hemolysin coding genes is more frequent among the E. coli which cause bacteremia. However, a two-dimensional analysis revealed that a combination of genes coding two adherence factors, namely, P + Dr, P + S, S + Dr, S + fim, and hemolysin + one adherence factor, were associated with bacteremia and, therefore, with the risk of translocation to the vascular system. The frequent and previously unrecognized co-existence of pro-inflammatory P fimbriae with the invasion promoting Dr adhesin in the same E. coli isolate may represent high-risk and potentially lethal pathogens.

Stented ureterovesical anastomosis in renal transplantation: does it influence the rate of urinary tract infections?

Objective

Our objective was to evaluate the impact of routine use of double-J stents on the incidence of urinary tract infection after renal transplantation.

Methods

We conducted a retrospective-comparative single-centre study in 310 consecutive adult deceased donor kidney recipients transplanted from 2002 to 2006. Patients were divided in two groups, with or without urinary stent implantation. To evaluate the predictive factors for UTI, donor and recipients pre- and post-transplantation data were analysed. Early urological complications and renal function within 12 months of transplantation were included as well.

Results

A total of 157 patients were enrolled to a stent (ST) and 153 patients to a no-stent (NST) group. The rate of urinary tract infection at three months was similar between the two groups (43.3% ST vs. 40.1% NST, p = 0.65). Of the identified pathogens Enterococcus and Escherichia coli were the most common species. In multivariate analysis neither age nor immunosuppressive agents, BMI or diabetes seemed to have influence on the rate of UTI. When compared to males, females had a significantly higher risk for UTI (54.0% vs. 33.5%).

Conclusion

Prophylactic stenting of the ureterovesical anastomosis does not increase the risk of urinary tract infection in the early postoperative period.

Urinary tract infections and asymptomatic bacteriuria in renal transplant recipients

Asymptomatic bacteriuria and urinary tract infection are common complications after kidney transplantation. In this population, if urinary tract infection occurred in the first six months post procedure, it carries a grave impact on both graft and patient survival. Renal transplant recipients with urinary tract infection are often clinically asymptomatic as a consequence of immunosuppression. Urinary tract infection, however, may progress to acute pyelonephritis, bacteremia and the full blown picture of urosepsis. PubMed and Cochrane databases were searched. The purpose of this review is to discuss the screening and treatment of urinary tract infection and asymptomatic bacteriuria in renal transplant recipients and to evaluate the guidelines on the basis of a review of published evidence.

Multidrug-resistant bacterial infection in solid organ transplant recipients

The most frequent complication from infection after solid organ transplantation is bacterial infection. This complication is more frequent in organ transplantation involving the abdominal cavity, such as liver or pancreas transplantation, and less frequent in heart transplant recipients. The sources, clinical characteristics, antibiotic resistance and clinical outcomes vary according to the time of onset after transplantation. Most bacterial infections during the first month post-transplantation are hospital acquired, and there is usually a high incidence of multidrug-resistant bacterial infections. The higher incidence of complications from bacterial infection in the first month post-transplantation may be associated with high morbidity. Of special interest due to their frequency are infections by S. aureus, enterococci, Gram-negative enteric and non-fermentative bacilli. Opportunistic bacterial infections may occur at any time on the posttransplant timeline, but are more frequent between months two and six, the period in which immunosuppression is higher. The most frequent bacterial species causing opportunistic infections in organ transplant recipients are Listeria monocytogenes and Nocardia spp. After month six, posttransplantation solid organ transplant patients usually develop conventional community-acquired bacterial infections, especially urinary tract infections by E. coli and S. pneumoniae pneumonia. In this article we review the clinical characteristics, epidemiology, diagnosis and prognosis of bacterial infections in solid organ transplant patients.

Urinary tract infection following kidney transplantation: frequency, risk factors and graft function

The aim of this study was to determine the proportion of children who develop urinary tract infection (UTI) after kidney transplantation (KTx) and to identify the factors associated with UTI and its impact on graft function. To this end, we undertook a chart review of children who underwent KTx at Red Cross Children's Hospital between January 2003 and December 2009 and were followed-up for at least 6 months after transplantation. Sixty-two children (53.2% males) were followed-up for a mean (standard deviation) period of 36.9 (19.7) months. Mean age at transplantation was 10.0 (4.6) years. Twenty-five (40.3%) children had 89 UTI episodes during the study period, equivalent to 0.94 UTI episodes per one patient-year of follow-up. Acute pyelonephritis occurred in 17 (27.4%) children; another 17 (27.4%) had multiple post-KTx UTI. Klebsiella (40.0%) and Escherichia (28.0%) were the commonest organisms. Those with post-KTx UTI were, at transplantation, younger (8.3 vs. 11.2 years; p = 0.017), had lower urinary tract abnormality (LUTA) (13 vs. 1; p = 0.000) and had pre-KTx UTI (13 vs. 5; p = 0.001). Multivariate analysis revealed that only age <5 years at transplantation and LUTA remained significant and that UTI KTx was not associated with worsening graft function. UTI is common after post-KTx. Among our patient cohort, younger age and LUTA were risk factors, but UTI did not affect graft function.

Role of Uropathogenic Escherichia coli Virulence Factors in Development of Urinary Tract Infection and Kidney Damage

Uropathogenic Escherichia coli (UPEC) is a causative agent in the vast majority of urinary tract infections (UTIs), including cystitis and pyelonephritis, and infectious complications, which may result in acute renal failure in healthy individuals as well as in renal transplant patients. UPEC expresses a multitude of virulence factors to break the inertia of the mucosal barrier. In response to the breach by UPEC into the normally sterile urinary tract, host inflammatory responses are triggered leading to cytokine production, neutrophil influx, and the exfoliation of infected bladder epithelial cells. Several signaling pathways activated during UPEC infection, including the pathways known to activate the innate immune response, interact with calcium-dependent signaling pathways. Some UPEC isolates, however, might possess strategies to delay or suppress the activation of components of the innate host response in the urinary tract. Studies published in the recent past provide new information regarding how virulence factors of uropathogenic E. coli are involved in activation of the innate host response. Despite numerous host defense mechanisms, UPEC can persist within the urinary tract and may serve as a reservoir for recurrent infections and serious complications. Presentation of the molecular details of these events is essential for development of successful strategies for prevention of human UTIs and urological complications associated with UTIs.

[Urinary tract infections after kidney transplantation: Essen algorithm for calculated antibiotic treatment]

Urinary tract infections are the most common infection early after transplantation and can affect long-term graft function. Any urinary tract infection in renal transplant recipients should be seen as "complex" with regard to consequences for diagnosis and therapy. The increase in resistance to anti-infective agents seen among uropathogens is one of the central therapeutic problems. This means for routine clinical practice that contact isolation precautions should be consistently implemented for affected patients and the duration of introducing urinary tract instruments should be minimized. Detection of pyuria and urine cultures are required to confirm infection, to identify the corresponding pathogen, and to review the antibiotic therapy.The "Essen algorithm for calculated antibiotic treatment of urinary tract infections in renal transplant patients" takes into consideration the high incidence of Gram-negative pathogens in general and the increased incidence of enterococci in the early phase after transplantation. Within the first 2 months after transplantation quinolones should be used and later cephalosporins. In case of urosepsis, calculated antibiotic therapy should cover problematic Gram-negative pathogens such as pseudomonades. The calculated antibiotic therapy should be administered intravenously in severe infections. In any case the local and regional antibiotic susceptibility should be taken into account when deciding on the calculated antibiotic therapy.

Urinary tract infections in renal transplant recipients: virulence traits of uropathogenic Escherichia coli

BACKGROUND

Urinary tract infection (UTI) is the most common infectious complication after renal transplantation. Most infections are caused by uropathogenic Escherichia coli (UPEC). There are limited data on the prevalence of virulence traits among UPEC isolated from renal transplant recipients. This study compared the phenotypic and genotypic profiles of UPEC strains isolated from recipients with those from control patients.

METHODS

E coli isolates that caused UTI in recipients versus nonimmunosuppressed control patients were characterized according to phylogenetic group and the presence of urovirulence genes pap1/pap2; sfa1/sfa2; afa1/afa2; aer1/aer2; and cnf1/cnf2.

RESULTS

Thirty-six UPEC isolates from recipients and another 27 from control individuals were included in the study. The proportion of episodes of pyelonephritis in recipients (50%) versus control subjects (41%) was similar (P = .46). However, secondary bacteremia was observed only among recipients (n = 8; P < .001). There was no significant difference in the distribution of phylogenetic groups or the prevalence of analyzed virulence traits between UPEC isolated from the 2 groups. Nevertheless, strains associated with secondary bacteremia in recipients showed a higher prevalence of mannose-resistant hemagglutination (P = .013).

CONCLUSION

The phenotypic and genotypic characteristics of UPEC isolated from recipients were similar to those from control patients at a tertiary care center. Secondary bacteremia in recipients was associated with a higher prevalence of mannose-resistant hemagglutination.

Urinary tract infections in renal transplant recipients

Urinary tract infection (UTI) is the most common infectious complication after renal transplantation. Although Escherichia coli remains the most common cause of UTI, Enterococcus spp and drug-resistant Enterobacteriaceae have emerged as important uropathogens in these patients. As a result, symptomatic UTIs warrant pathogen-specific antibiotic therapy guided by culture and susceptibility data. In the early transplant period, prophylaxis of UTI with trimethoprim-sulfamethoxazole is generally effective. Until the natural history and optimal management of asymptomatic bacteruria are better defined, therapy of asymptomatic bacteruria is generally unnecessary.

The role of host factors and bacterial virulence genes in the development of pyelonephritis caused by Escherichia coli in renal transplant recipients

BACKGROUND AND OBJECTIVES

The aim of this study was to determine the role of host factors and bacterial virulence genes in the development of pyelonephritis caused by Escherichia coli in renal transplant (Tx) recipients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A total of 328 E. coli isolates from cases of cystitis (Cys; n=239) or pyelonephritis (PN; n=89), with 169 from renal Tx recipients, were subjected to molecular analyses to identify P-fimbria subunits (PapC, PapG II, and PapGIII), G- and M-fimbriae, and aerobactin. The presence of antibiotic resistance was also determined. Parameters such as gender, age, immunosuppression regimens, causes of ESRD, kidney donor, intraoperative anastomosis, use of double J stent, trimethoprim/sulfamethoxazole (TMP/SMZ) prophylaxis, and time after Tx were evaluated.

RESULTS

A multivariate analysis showed a significant association between PN and renal Tx. In renal Tx recipients, the risk of occurrence of PN was significantly higher among males and for those no longer receiving TMP/SMZ prophylaxis. E. coli strains isolated from PN presented a lower prevalence of papGIII and lower rates of resistance to pipemidic acid. Although papGII was more prevalent in PN than in Cys, it was not independently associated with PN.

CONCLUSIONS

These findings suggested that renal Tx increases the risk for PN, and the male sex represented a host factor independently associated with risk, whereas the prophylaxis with TMP/SMZ was protective. The lack of papGIII and low resistance to first-generation quinolones were bacterial-independent risk factors for PN in Tx.

Escherichia coli sequence type ST131 as an emerging fluoroquinolone-resistant uropathogen among renal transplant recipients

Among 40 Escherichia coli urine isolates from renal transplant recipients (Galveston, TX, 2003 to 2005), sequence type ST131 (O25:H4) was highly prevalent (representing 35% of isolates overall and 60% of fluoroquinolone-resistant isolates), virulent appearing, antimicrobial resistant (but extended-spectrum-cephalosporin susceptible), and associated with black race. Pulsotypes were diverse; some were linked to other locales. ST131 emerged significantly during the study period. These findings suggest that E. coli ST131 may constitute an important new multidrug-resistant threat to renal transplant recipients.