Antibiotic Treatment Versus No Treatment for Asymptomatic Bacteriuria in Kidney Transplant Recipients: A Multicenter Randomized Trial

Initial empirical antibiotic therapy in kidney transplant recipients with pyelonephritis: A global survey of current practice and opinions across 19 countries on six continents

BACKGROUND

Despite the burden of pyelonephritis after kidney transplantation, there is no consensus on initial empirical antibiotic management.

METHODS

We surveyed clinicians throughout the world on their practice and opinions about the initial empirical therapy of post-transplant pyelonephritis, using clinical vignettes. A panel of experts from 19 countries on six continents designed this survey, and invited 2145 clinicians to participate.

RESULTS

A total of 721 clinicians completed the survey (response rate: 34%). In the hypothetical case of a kidney transplant recipient admitted with pyelonephritis but not requiring intensive care, most respondents reported initiating either a 3rd-generation cephalosporin (37%) or piperacillin-tazobactam (21%) monotherapy. Several patient-level factors dictated the selection of broader-spectrum antibiotics, including having a recent urine culture showing growth of a resistant organism (85% for extended-spectrum ß-lactamase-producing organisms, 90% for carbapenemase-producing organisms, and 94% for Pseudomonas aeruginosa). Respondents attributed high importance to the appropriateness of empirical therapy, which 87% judged important to prevent mortality. Significant practice and opinion variations were observed between and within countries.

CONCLUSION

High-quality studies are needed to guide the empirical management of post-transplant pyelonephritis. In particular, whether prior urine culture results should systematically be reviewed and considered remains to be determined. Studies are also needed to clarify the relationship between the appropriateness of initial empirical therapy and outcomes of post-transplant pyelonephritis.

Therapeutic Myths in Solid Organ Transplantation Infectious Diseases

Infection management in solid organ transplantation poses unique challenges, with a diverse array of potential pathogens and associated antimicrobial therapies. With limited high-quality randomized clinical trials to direct optimal care, therapeutic "myths" may propagate and contribute to suboptimal or excessive antimicrobial use. We discuss 6 therapeutic myths with particular relevance to solid organ transplantation and provide recommendations for infectious diseases clinicians involved in the care of this high-risk population.

Monocyte-derived dendritic cells can be detected in urine of kidney transplant recipients with pathogenic asymptomatic bacteriuria

Urinary tract infections (UTI) are an important clinical problem in kidney transplant recipients (KTR). Asymptomatic bacteriuria (ASB) is frequent in these patients and often resolved by the immune system, but a significant proportion may progress to complicated UTI, which may compromise allograft function and survival. It is essential to determine the involvement of the immune system in the infectious process. Dendritic cells (DCs) are recognised as playing a pivotal role in initiating inflammatory responses capable of priming antigen-specific T cells, a crucial step in determining the fate of local inflammation. Little is known about their role in the control of UTI. In this brief communication, we report an incidental finding in a group of 16 stable KTR in which monocyte-derived dendritic cells (ModDCs), analysed by flow cytometry, were found in urine of patients with ASB and high bacterial counts >107 cfu/ml. Within this group, one patient developed pyelonephritis in the following days. These findings suggest that the immune system, in particular DCs, may be recruited during the course of a UTI and, to our knowledge, present for the first time evidence that inflammatory ModDCs can be detected in urine. Their frequency may reflect the degree of infection. This finding suggests the potential for exploring whether these cells may be useful in distinguishing between pathogenic ASB and those that can be resolved by the immune system.

Diagnosing and Managing Urinary Tract Infections in Kidney Transplant Recipients

In the article, the authors review antibiotic treatment options for both acute uncomplicated UTI and complicated UTI. In addition, they review alternative regimens which are needed in the setting of drug-resistant pathogens including vancomycin-resistant Enterococcus, -extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-E), carbapenem-resistant Enterobacterales, and carbapenem-resistant Pseudomonas, which are encountered with more frequency.

Systematic Review and Meta-Analysis Provide no Guidance on Management of Asymptomatic Bacteriuria within the First Year after Kidney Transplantation

(1) Background: Urinary tract infections (UTIs) are among the most frequent complications in kidney transplant (KT) recipients. Asymptomatic bacteriuria (ASB) may be a risk factor for UTIs and graft rejection. We aimed to evaluate available evidence regarding the benefit of screening and treatment of ASB within the first year after KT. (2) Evidence acquisition: A systematic literature search was conducted in MEDLINE, the Cochrane Library CENTRAL and Embase. Inclusion criteria were manuscripts in English addressing the management of ASB after KT. The PICO questions concerned Patients (adults receiving a KT), Intervention (screening, diagnosis and treatment of ASB), Control (screening and no antibiotic treatment) and Outcome (UTIs, sepsis, kidney failure and death). (3) Evidence synthesis: The systematic review identified 151 studies, and 16 full-text articles were evaluated. Seven were excluded because they did not evaluate the effect of treatment of ASB. There was no evidence for a higher incidence of lower UTIs, acute pyelonephritis, graft loss, or mortality in patients not treated with antibiotics for ASB. Analysis of comparative non-randomized and observational studies did not provide supplementary evidence to guide clinical recommendations. We believe this lack of evidence is due to confounding risk factors that are not being considered in the stratification of study patients.

"Electronic Phenotyping" Antimicrobials to Facilitate Outpatient Stewardship for Asymptomatic Bacteriuria and Urinary Tract Infection in Renal Transplant

Asymptomatic bacteriuria and urinary tract infection in renal transplant are important antimicrobial stewardship targets but are difficult to identify within electronic medical records. We validated an "electronic phenotype" of antibacterials prescribed for these indications. This may be more useful than billing data in assessing antibiotic indication in this outpatient setting.

Acidic Urine pH and Clinical Outcome of Lower Urinary Tract Infection in Kidney Transplant Recipients Treated with Ciprofloxacin and Fosfomycin

Different factors, including antimicrobial resistance, may diminish the effectiveness of antibiotic therapy, challenging the management of post-transplant urinary tract infection (UTI). The association of acidic urine pH with microbiological and clinical outcomes was evaluated after fosfomycin or ciprofloxacin therapy in 184 kidney transplant recipients (KTRs) with UTI episodes by Escherichia coli (N = 115) and Klebsiella pneumoniae (N = 69). Initial urine pH, antimicrobial therapy, and clinical and microbiological outcomes, and one- and six-month follow-up were assessed. Fosfomycin was prescribed in 88 (76.5%) E. coli and 46 (66.7%) K. pneumoniae UTI episodes in the total cohort. When the urine pH ≤ 6, fosfomycin was prescribed in 60 (52.2%) E. coli and 29 (42.0%) K. pneumoniae. Initial urine pH ≤ 6 in E. coli UTI was associated with symptomatic episodes (8/60 vs. 0/55, p = 0.04) at one-month follow-up, with a similar trend in those patients receiving fosfomycin (7/47 vs. 0/41, p = 0.09). Acidic urine pH was not associated with microbiological or clinical cure in K. pneumoniae UTI. At pH 5, the ciprofloxacin MIC90 increased from 8 to >8 mg/L in E. coli and from 4 to >8 mg/L in K. pneumoniae. At pH 5, the fosfomycin MIC90 decreased from 8 to 4 mg/L in E. coli and from 512 to 128 mg/L in K. pneumoniae. Acidic urine is not associated with the microbiological efficacy of fosfomycin and ciprofloxacin in KTRs with UTI, but it is associated with symptomatic UTI episodes at one-month follow-up in E. coli episodes.

Bring it on again: antimicrobial stewardship in transplant infectious diseases: updates and new challenges

Advancement in solid organ transplantation and hematopoietic stem cell transplant continues to improve the health outcomes of patients and widens the number of eligible patients who can benefit from the medical progress. Preserving the effectiveness of antimicrobials remains crucial, as otherwise transplant surgeries would be unsafe due to surgical site infections, and the risk of sepsis with neutropenia would preclude stem cell transplant. In this review, we provide updates on three previously discussed stewardship challenges: febrile neutropenia, Clostridioides difficile infection, and asymptomatic bacteriuria. We also offer insight into four new stewardship challenges: the applicability of the "shorter is better" paradigm shift to antimicrobial duration; antibiotic allergy delabeling and desensitization; colonization with multidrug-resistant gram-negative organisms; and management of cytomegalovirus infections. Specifically, data are accumulating for "shorter is better" and antibiotic allergy delabeling in transplant patients, following successes in the general population. Unique to transplant patients are the impact of multidrug-resistant organism colonization on clinical decision-making of antibiotic prophylaxis in transplant procedure and the need for antiviral stewardship in cytomegalovirus. We highlighted the expansion of antimicrobial stewardship interventions as potential solutions for these challenges, as well as gaps in knowledge and opportunities for further research.

Profile, Risk Factors, and Outcomes of Asymptomatic Bacteriuria in Kidney Transplant Recipients with Normal Pretransplant Genitourinary Tract: A Single-Center Experience

Introduction

There is a paucity of studies on asymptomatic bacteriuria (ASB) among kidney transplant recipients (KTR) in developing countries. This study assessed the clinical profile, risk factors, outcomes, and impact of treatment of ASB in KTRs with a normal genitourinary tract.

Methods

Consecutive KTRs from 2009 to 2018 with no clinical or radiological evidence of obstructive uropathy were included. Urinary tract infection (UTI) after ASB was defined as occurrence of cystitis, pyelonephritis, or urosepsis, with ASB being the first bacteriuric episode.

Results

Seven hundred ten out of 794 patients with median follow up of 47 months were included. The mean age was 35.5 ± 12 years. Eighty-one patients (11.4%) developed ASB at a median of 25 days (IQR 10, 134.5). Fifty-three percent and 4.9% of ASB episodes were extended-spectrum beta-lactamase (ESBL) positive and carbapenem-resistant organisms, respectively. Eighteen patients (32.1%) with early ASB (<3 months) and 5 (20%) with late ASB developed UTI on follow-up. Fifty-five percent of early and 16% of late ASB episodes were treated, with no significant difference observed in the risk of development of UTI when compared to untreated ASB episodes.

Conclusion

The incidence of ASB as first bacteriuric episode in our cohort was 11.4%, with there being significant antimicrobial resistance. Female gender, pretransplant UTI, and delayed graft function were independently associated with development of ASB. Treatment of ASB episodes either early or late did not decrease the risk of development of UTI.

Antimicrobial Stewardship in Immunocompromised Patients: Current State and Future Opportunities

Immunocompromised (IC) patients are high risk for complications due to a high rate of antibiotic exposure. Antimicrobial stewardship interventions targeted to IC patients can be challenging due to limited data in this population and a high risk of severe infection-related outcomes. Here, the authors review immunocompromised antimicrobial stewardship barriers, metrics, and opportunities for antimicrobial use and testing optimization. Last, the authors highlight future steps in the field.

Shorter antibiotic courses in the immunocompromised: the impossible dream?

BACKGROUND

A growing number of studies have demonstrated similar outcomes with shorter courses of antibiotics for bacterial infections. Immunocompromised patients are frequently excluded from these studies despite anticipated benefits associated with shortening antibiotic courses (including lower risks of antibiotic toxicity, Clostridioides difficile infection, drug-resistant pathogens, and microbiome alterations).

OBJECTIVES

To critically review the literature that assesses shorter antibiotic courses in immunocompromised patients, specifically among solid organ transplant recipients and neutropenic fever (NF) syndromes among patients on antineoplastic chemotherapy and undergoing haematopoietic cell transplant.

SOURCES

References were identified through searches of PubMed, Embase, MEDLINE, and clinical guidelines documents.

CONTENT

Among organ transplant recipients, the majority of studies assessing outcomes associated with shorter antibiotic courses have been retrospective but have demonstrated similar rates of clinically relevant endpoints. Patients with high- and low-risk NF have been well-studied, including enrolment in randomized studies, albeit with heterogeneous patient populations and outcomes assessed. Clinical improvement-guided adoption of shorter courses has been associated with fewer antibiotic days and similar rates of fever recurrence and mortality.

IMPLICATIONS

Similar to studies demonstrating efficacy in immunocompetent patients, shorter antibiotic courses should be considered for immunocompromised hosts with presumed bacterial infections. Organ recipients and patients with NF syndromes should be prioritized for study in randomized controlled clinical trials assessing shorter course therapy.

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.

Application of Various Techniques to Gain Insights Into the Complex Urinary Tract Microbial Communities of Renal Transplant Recipients

Urinary tract infections (UTIs) are prevalent in renal transplant (RT_X) recipients and associated with worse outcomes. Early detection by sensitive diagnostic tests and appropriate treatment strategies in this cohort is therefore crucial, but evidence has shown that current methods may miss genuine infections. Research has shed light on the urinary tract microbial ecology of healthy individuals and nontransplant patients with UTI, but information on the RTx cohort is scant. We conducted a cross-sectional study to (i) compare the gold standard diagnostic culture with alternative techniques and (ii) characterize RTx patient urinary microbial communities.

Methods

Midstream urine specimens were collected from 51 RTx patients attending a renal transplant clinic and 27 asymptomatic controls. Urinary microscopy, dipstick, and routine culture were performed. To improve sensitivity of microbial detection, we cultured the urinary cell sediment and performed 16S rRNA gene sequencing on urine. Uroplakin-positive urothelial cells shed in urine were analyzed by immunofluorescence staining for any bacterial association.

Results

Sediment culture and 16S rRNA sequencing confirmed detection deficiencies of diagnostic culture and revealed differences in the urobiomes of RTx patients and controls. Specifically, Gardnerella, Escherichia, and Lactobacillus were most abundant in patients, whereas Lactobacillus, Streptococcus, and Gardnerella were most abundant in controls. The application of both culture and sequencing provided a more nuanced view of the urinary microbial communities.

Conclusions

This study provides insight into the potential problems of diagnostic culture within RTx patients and sheds light on their urinary microbial inhabitants. Further work may identify key microbial signatures and facilitate the development of better tools for UTI detection within this cohort, which could allow targeted intervention before an infection leads to serious consequences. http://links.lww.com/TXD/A479.

Treatment of asymptomatic bacteriuria in the first 2 months after kidney transplant: A controlled clinical trial

BACKGROUND

The incidence of urinary tract infections (UTIs) in the first 2 months postrenal transplantation (pRT) is very high. We evaluate the efficacy of asymptomatic bacteriuria (AB) screening and treatment on the incidence of UTI in the first 2 months pRT METHODS: We conducted a randomized controlled clinical trial. A urine culture was obtained in all patients on the day of the bladder catheter removal, on week three, and before removal of the ureteral catheter. The intervention group received treatment for AB. The control group did not receive treatment. The primary outcomes were the cumulative incidence of UTI and/or graft pyelonephritis and the time to the first episode of UTI and/or graft pyelonephritis RESULTS: Eighty patients were randomized, 40 in each group, and the median follow-up was 63 days (IQR 54-70). The average age was 29.8 years and 33.7% (n = 27) were women. The incidences of UTI (n = 10, 25 % vs. n = 4, 10%, p = .07) and pyelonephritis (n = 6, 15% vs. n = 1, 2.5%, p = .04) were greater in the intervention group, as also shown in the survival analysis: UTI (HR2.8, 95% CI 0.8-9.1, p = .07) and pyelonephritis (HR 6.5, 95% CI 0.8-54.7, p = .08), respectively. The most commonly isolated bacterium was Escherichia coli (n = 28, 59.5%), and over half were E. coli with extended-spectrum beta-lactamases (n = 15). A major limitation was not obtaining the calculated sample size due to a delay in patient recruitment resulting from the COVID-19 pandemic CONCLUSION: Treatment of AB in the first 2 months pRT does not decrease the incidence of UTI or graft pyelonephritis and may actually increase their frequency. Routine treatment of AB during the first months after renal transplantation should not be a standard procedure.

Bacterial Urinary Tract Infection and Early Asymptomatic Bacteriuria in Kidney Transplantation Still Negatively Affect Kidney Transplant Outcomes in the Era of Modern Immunosuppression and Cotrimoxazole Prophylaxis

Risk factors and consequences of urinary tract infection (UTI) post-kidney transplant have been variously reported by studies that were heterogenous in immunosuppressants and prophylactic protocols. We aimed to clarify the risks and consequences of UTI in kidney transplant recipients with post-transplantation cotrimoxazole prophylaxis in the context of modern immunosuppression. This retrospective cohort included kidney transplant recipients receiving tacrolimus, mycophenolate, prednisolone, and cotrimoxazole for bacterial UTI prophylaxis. Recipients were categorized into non-UTI and UTI groups. Asymptomatic bacteriuria (ASB) was screened in the first 3 months and was evaluated for association with UTI. Of 348 kidney transplant recipients, 129 were in the UTI group and 219 in the non-UTI group. UTI risk factors were female sex, body mass index ≥ 25 kg/m², human leukocyte antigen mismatch, and panel reactive antibody ≥ 50%. Recipients with recurrent UTI had inferior allograft function compared with non-UTI recipients. Patient survival was significantly lower in recipients with UTI in the first post-transplant month. Higher degree of immunosuppressions was associated with recurrent UTI and drug-resistant organisms. In conclusion, UTI continues to negatively affect graft function and survival of kidney transplant recipients. Treating ASB in the first 3 months did not reduce the UTI incidence in the first transplantation year.

Shorter durations of antibiotic therapy in organ transplant

PURPOSE OF REVIEW

Recent evidence supports shorter courses of antibiotics for several common infections and prophylactic indications. Unfortunately, solid organ transplant patients are often underrepresented or excluded from these studies. As a result, prolonged antibiotic durations are often used in clinical practice despite a lack of demonstrable benefit. This paper reviews recent publications addressing antibiotic duration of therapy in SOT recipients.

RECENT FINDINGS

Although largely limited to observational studies, longer courses of antibiotics for surgical prophylaxis, urinary tract infections, and bloodstream infections have not demonstrated benefit compared to shorter courses. In some instances, longer courses of therapy have been associated with harm (i.e., adverse drug events and development of resistance).

SUMMARY

Although the data remains limited, findings from retrospective studies evaluating shorter courses of antibiotics in SOT patients is encouraging. More robust research is desperately needed to define the optimal duration of antibiotics for common infections in SOT patients.

Bring it on: Top five antimicrobial stewardship challenges in transplant infectious diseases and practical strategies to address them

Antimicrobial therapies are essential tools for transplant recipients who are at high risk for infectious complications. However, judicious use of antimicrobials is critical to preventing the development of antimicrobial resistance. Treatment of multidrug-resistant organisms is challenging and potentially leads to therapies with higher toxicities, intravenous access, and intensive drug monitoring for interactions. Antimicrobial stewardship programs are crucial in the prevention of antimicrobial resistance, though balancing these strategies with the need for early and frequent antibiotic therapy in these immunocompromised patients can be challenging. In this review, we summarize 5 frequently encountered transplant infectious disease stewardship challenges, and we suggest strategies to improve practices for each clinical syndrome. These 5 challenging areas are: asymptomatic bacteriuria in kidney transplant recipients, febrile neutropenia in hematopoietic stem cell transplantation, antifungal prophylaxis in liver and lung transplantation, treatment of left-ventricular assist device infections, and Clostridioides difficile infection in solid-organ and hematopoietic stem-cell transplant recipients. Common themes contributing to these challenges include limited data specific to transplant patients, shortcomings in diagnostic testing, and uncertainties in pharmacotherapy.

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.

Urinary Tract Infections in the First 6 Months after Renal Transplantation

Purpose

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

Methods

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

Results

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

Conclusion

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

Therapeutic failures of targeted antibiotic prophylaxis in urology

Targeted antibiotic prophylaxis (TAP) is required for patients with positive urine culture before urological surgery. Our aim was to determine the efficacy of TAP. This was a prospective single-center study performed in a urology department. All patients who underwent a programmed surgery were included. Urine culture was obtained before surgery requiring a prophylaxis: in the case of sterile urines, antibiotics were used in accordance with national recommendations; for positive urine culture, a TAP was used in accordance with susceptibility testing. The drugs were administered for 2 days before surgery until withdrawal of bladder catheter. The occurrence of healthcare-associated infections was registered until day 30 after surgery. Two hundred three patients were included for 8 non-consecutive weeks in 2020, among whom fifteen were lost of sight before day 30. Among the remaining 188 patients, most frequent surgeries were 75 prostatic diseases (40%), 50 endo-ureteral surgeries for JJ stent insertion (27%), and 23 bladder cancers (12%). One hundred forty-eight (79%) patients required a urine culture before procedure; 142/148 (96%) urine cultures were performed, leading to 74 TAP. The main isolated bacteria were 48 Enterobacteriaceae and 8 Enterococcus spp. TAP was cotrimoxazole (n = 30), aminoglycosides (n = 11), amoxicillin (n = 9), fluoroquinolones (n = 7), and others (n = 17). The rate of healthcare-associated infections was 14.8% (11/74), including six microbiologically documented antibiotic failures. The rate of healthcare-associated infection after urological surgery using TAP was high, implying to discuss the choice and the dosage of the antibiotic molecules.

Chronic Kidney Allograft Disease: New Concepts and Opportunities

Chronic kidney disease (CKD) is increasing in most countries and kidney transplantation is the best option for those patients requiring renal replacement therapy. Therefore, there is a significant number of patients living with a functioning kidney allograft. However, progressive kidney allograft functional deterioration remains unchanged despite of major advances in the field. After the first post-transplant year, it has been estimated that this chronic allograft damage may cause a 5% graft loss per year. Most studies focused on mechanisms of kidney graft damage, especially on ischemia-reperfusion injury, alloimmunity, nephrotoxicity, infection and disease recurrence. Thus, therapeutic interventions focus on those modifiable factors associated with chronic kidney allograft disease (CKaD). There are strategies to reduce ischemia-reperfusion injury, to improve the immunologic risk stratification and monitoring, to reduce calcineurin-inhibitor exposure and to identify recurrence of primary renal disease early. On the other hand, control of risk factors for chronic disease progression are particularly relevant as kidney transplantation is inherently associated with renal mass reduction. However, despite progress in pathophysiology and interventions, clinical advances in terms of long-term kidney allograft survival have been subtle. New approaches are needed and probably a holistic view can help. Chronic kidney allograft deterioration is probably the consequence of damage from various etiologies but can be attenuated by kidney repair mechanisms. Thus, besides immunological and other mechanisms of damage, the intrinsic repair kidney graft capacity should be considered to generate new hypothesis and potential therapeutic targets. In this review, the critical risk factors that define CKaD will be discussed but also how the renal mechanisms of regeneration could contribute to a change chronic kidney allograft disease paradigm.

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.

Asymptomatic Bacteriuria in Post Renal Transplant Patients: To Treat or Not?

Urinary tract infections (UTIs) can commonly occur within the first few weeks following kidney transplantation procedures. Although the management of asymptomatic bacteriuria and acute graft pyelonephritis is important to reduce the risk of graft rejections following kidney transplantation, the efficacy of antibiotics administration remains controversial among studies in the literature. The aim of this review is to elaborate more on asymptomatic bacteriuria following kidney transplantation and try to formulate proper evidence about the efficacy of antibiotics administration on eliminating the frequency of infections and enhancing the quality of care for patients. Most studies in the literature are observational, which are usually biased in the interventions. However, the current evidence regarding the management and screening of asymptomatic bacteriuria seems to discourage such an approach. Almost all of the included studies reported that antibiotic administration did not significantly lower the rates of secondary symptomatic UTIs or enhance the functions of the graft. In addition, there is no significant impact on mortality and other clinical outcomes. Lastly, the frequent administration of antibiotics can significantly increase the risk of recurrence due to the emergence of novel strains of bacteria that are resistant to the currently administered antibiotics making it unfavorable.

Efficacy and safety of oral fosfomycin for asymptomatic bacteriuria in kidney transplant recipients: Results from a Spanish multicenter cohort

Current guidelines recommend against systematic screening or treating asymptomatic bacteriuria (AB) among kidney transplant (KT) recipients, although the evidence regarding episodes occurring early after transplantation or in the presence of anatomical abnormalities is inconclusive. Oral fosfomycin may constitute a good option for the treatment of post-transplant AB, particularly due to the emergence of multidrug-resistant (MDR) uropathogens. Available clinical evidence supporting its use in this specific setting, however, remains scarce. We performed a retrospective study in 14 Spanish institutions from January 2005 to December 2017. Overall, 137 episodes of AB diagnosed in 133 KT recipients treated with oral fosfomycin (calcium and trometamol salts) with a test-of-cure urine culture within the first 30 days were included. Median time from transplantation to diagnosis was 3.1 months (interquartile range [IQR]: 1.1 - 10.5). Most episodes (96.4% [132/137]) were caused by gram-negative bacteria (GNB), and 56.9% (78/137) were categorized as MDR (extended-spectrum β-lactamase-producing Enterobacterales [20.4%] and carbapenem-resistant GNB [2.9%]). Rate of microbiological failure at month 1 was 40.1% (95% confidence interval [95%CI]: 31.9 - 48.9) for the whole cohort and 42.3% (95%CI: 31.2 - 54.0) for episodes due to MDR pathogens. Previous urinary tract infection (odds ratio [OR]: 2.42; 95%CI: 1.11 - 5.29; P-value = 0.027) and use of fosfomycin as salvage therapy (OR: 8.31; 95%CI: 1.67 - 41.35; P-value = 0.010) were predictors of microbiological failure. No severe treatment-related adverse event were detected. Oral fosfomycin appears to be a suitable and safe alternative for the treatment (if indicated) of AB after KT, including those episodes due to MDR uropathogens.

Impact of Treating Asymptomatic Bacteriuria in Kidney Transplant Recipients: A Prospective Cohort Study

This study aims to define the epidemiologic, clinical, and microbiological features of asymptomatic bacteriuria (AB) and cystitis in kidney transplantation recipients (KTRs), and to determine the impact of antimicrobial therapy of AB and the risk factors of cystitis. We conducted a prospective observational study of AB and cystitis in KTRs from January to June 2017. One-hundred ninety seven KTRs were included: 175 (88.8%) with AB and 22 (11.2%) with cystitis. The most frequent etiologies were Escherichia coli, Klebsiellapneumoniae, Enterococcusfaecalis, and Pseudomonas aeruginosa. No differences were observed regarding the etiologies, antimicrobial susceptibility patterns, and microbiologic outcomes in AB vs. cystitis. The treatment of AB diminished the microbiological cure and increased the rates of microbiologic relapses and reinfections; in addition, treated AB patients showed a trend of developing symptomatic urinary tract infection in the following six months. The analysis of the data identified the following independent risk factors for cystitis during the six months of follow-up: AB treatment, thymoglobulin induction, previous acute pyelonephritis, and time since transplantation < 1 year. In summary, considering the lack of clinical benefits of treating AB and its impact on cystitis development in the follow-up, we support the recommendation of not screening for or treating AB.

Antibiotics versus no therapy in kidney transplant recipients with asymptomatic bacteriuria (BiRT): a pragmatic, multicentre, randomized, controlled trial

OBJECTIVES

Many transplant physicians screen for and treat asymptomatic bacteriuria (ASB) during post-kidney-transplant surveillance. We investigated whether antibiotics are effective in reducing the occurrence of symptomatic urinary tract infection (UTI) in kidney transplant recipients with ASB.

METHODS

We performed this multicentre, randomized, open-label trial in kidney transplant recipients who had ASB and were ≥2 months post-transplantation. We randomly assigned participants to receive antibiotics or no therapy. The primary outcome was the incidence of symptomatic UTI over the subsequent 12 months.

RESULTS

One hundred and ninety-nine kidney transplant recipients with ASB were randomly assigned to antibiotics (100 participants) or no therapy (99 participants). There was no significant difference in the occurrence of symptomatic UTI between the antibiotic and no-therapy groups (27%, 27/100 versus 31%, 31/99; univariate Cox model: hazard ratio 0.83, 95%CI: 0.50-1.40; log-rank test: p 0.49). Over the 1-year study period, antibiotic use was five times higher in the antibiotic group than in the no-therapy group (30 antibiotic days/participant, interquartile range 20-41, versus 6, interquartile range 0-15, p < 0.001). Overall, 155/199 participants (78%) had at least one further episode of bacteriuria during the follow-up. Compared with the participant's baseline episode of ASB, the second episode of bacteriuria was more frequently caused by bacteria resistant to clinically relevant antibiotics (ciprofloxacin, cotrimoxazole, third-generation cephalosporin) in the antibiotic group than in the no-therapy group (18%, 13/72 versus 4%, 3/83, p 0.003).

CONCLUSIONS

Applying a screen-and-treat strategy for ASB does not reduce the occurrence of symptomatic UTI in kidney transplant recipients who are more than 2 months post-transplantation. Furthermore, this strategy increases antibiotic use and promotes the emergence of resistant organisms.