Urinary tract infections in renal transplant recipients

Urinary tract infection (UTI) is the most common infectious complication following renal transplantation. The purposes of this study were to determine the causative agents of UTIs among renal transplant recipients and to compare the antibiotic susceptibilities of Escherichia coli strains isolated from renal transplant recipients and complicated community-acquired UTIs. We evaluated 75 episodes of 63 recipients with confirmed UTI who underwent transplantation during the period 1981 to 2006 at our center. Medical records of the patients were reviewed retrospectively. To compare the susceptibility rates of E coli, 226 isolates from nontransplant patients with complicated community-acquired UTIs were also evaluated. Ten episodes (13.3%) occurred in the first month following the transplantation, 11 (14.7%) in the period of the second month to the sixth month, and 54 (72%) after the sixth month of transplantation. Forty-six (61.3%) isolates were E coli. Among these isolates, ciprofloxacin resistance rates were 50% (2/4) in the first month after transplantation, 75% (6/8) in the period of the second month to the sixth month, and 32.4% (11/34) beyond 6 months after transplantation. The resistance rates of trimethoprim/sulfamethoxazole (TMP-SMX) in the same time periods were 100% (4/4), 87.5% (7/8), and 70.6% (24/34), respectively. The rates of resistance to TMP-SMX among E coli isolated from renal recipients were significantly higher than those in community-acquired complicated UTIs. The increased resistance of urinary pathogens to this agent is a major concern. Although high resistance rates of ciprofloxacin against E coli strains were determined in this group, it was not found to be statistically significant.     

Urinary tract infections in renal transplant recipients

Introduction

Urinary tract infections (UTIs) are most common infections in renal transplant recipients and are considered a potential risk factor for poorer graft outcomes.

Aim

To evaluate incidence, clinical manifestations, microbiology, risk factors for UTIs, and the influence of UTIs on long-term renal graft function.

Patients and methods

We analyzed urine cultures with reference to clinical data of patients who received a renal transplantation from January to December 2009 with a 12-month follow-up.

Results

The 1170 urine cultures were correlated with clinical data from 89 renal transplant recipients, including 58.4% males and on overall mean age of 48 ± 14 years. The 151 episodes in 49 patients consisted of asymptomatic bacteriuria (65%, n = 98); lower UTIs (13%, n = 19); and upper UTIs (22%, n = 34), as well as five cases of bacteremia. Nearly 48% of UTIs were diagnosed during the first month posttransplantation. The most frequently isolated uropathogens were Enterococcus faecium (33%, n = 24) and Escherichia coli (31%, n = 23). Beginning from the second month, most frequently found bacterium in urine cultures was E coli (65% n = 51). Risk factors for posttransplant UTIs were female gender and a history of an acute rejection episode and/or a cytomegalovirus (CMV) infection. All patients with vesicoureteral reflux of strictures at the ureterovesical junction suffered recurrent UTIs (n = 7). The evolution of renal graft function did not differ significantly between patients with versus without UTIs.

Conclusions

UTIs a frequent problem after kidney transplantation most commonly exist as asymptomatic bacteriuria. E coli and E faecium are ther predominant pathogens. Exposure to intensified immunosuppression due to acute rejection episodes or CMV infections represents a risk factor for UTIs. Vesicoureteral reflux or strictures at the ureterovesical junction are risk factors for recurrent UTIs. UTIs did not impair 1-year graft function.     

Urinary tract infections in post-renal transplant patients

The overall incidence of urinary tract infections (UTIs) in our renal transplant population was 30.9%, i.e. 0.15 episode per patient-year. UTIs occurred more often within the first 3 months (60%) of transplantation. Fifty per cent of UTIs were asymptomatic. Recurrences were common. Acute tubular necrosis and cellular rejections were important associations. UTIs had little effect on graft function and survival up to 3 years post-transplant.     

Urinary tract infections after kidney transplantation]

Clinical significance of urinary tract infections (UTI) after kidney transplantation was studied in 57 cases. Of these patients, the UTI occurred in 63% of cases during follow-up after transplantation. Although the bacteriuria were observed more frequently in living-related donor (LD) group at pre-operation, cadaveric donor (CD) group showed significantly higher frequency in bacteriuria and UTI after transplantation. The initial UTI occurred within 4 weeks after transplantation in 86% of cases. The significant risk factors in the occurrence of UTI were presence of bacteriuria in post-operation, CD group, mismatch numbers in HLA, amount of steroid, and ages of donor and recipient. Of the bacteria isolated, about half were pathogens in UTI, which was a 2 times higher risk compared with the time of chronic hemodialysis. Gram negative rods were found to be major pathogen in UTI cases. The effect of UTI on graft survival was not obvious. However, of the patients who have bacteriuria at operation, 52% were found to have bacteriuria due to the same strain during follow-up. Therefore, bacteriological examination of urine at transplantation must be done carefully.     

肾移植受者术后感染临床分析

目的探究肾移植受者术后感染情况及其危险因素。 方法回顾性分析2018年1月1日至12月31日于首都医科大学附属北京友谊医院接受肾移植的94例受者临床资料。供肾均采用Lifeport行低温机械灌注,并向灌注液中加入头孢哌酮舒巴坦钠以预防供者来源感染。根据受者术后3个月内体液培养结果,将94例受者分为感染组和对照组。采用卡方检验比较感染组和对照组受者性别、灌注液培养阳性比例和移植肾功能延迟恢复(DGF)发生率。采用Wilcoxon符号秩和检验比较两组受者年龄、移植前血清肌酐水平和住院时间。将单因素分析中有统计学差异的变量纳入Logistic回归进行多因素分析。P<0.05为差异有统计学意义。 结果术后3个月内94例受者中41例受者血、尿、痰及引流液标本中培养出病原菌,感染率为43.6%(41/94),且感染多发生于术后1周至1个月内,占34.0%(32/94)。41例受者共发生58例次感染,病原菌多来源于泌尿系统感染,占51.7%(30/58),其次为手术部位和血液系统感染,分别占32.8%(19/58)和13.8%(8/58),呼吸道感染占比最低,为1.7%(1/58)。27例受者为单一病原菌感染,14例为2种及以上病原菌感染。41例受者共分离出66株病原菌,其中细菌占89.4%(59/66),真菌占10.6%(7/66)。截至2019年7月10日,94例受者均存活,所有感染经治疗后均好转,未出现严重感染性疾病或因感染发生移植物丢失。单因素分析结果表明,感染组与对照组年龄、性别、移植前血清肌酐水平及住院时间差异均无统计学意义(z＝－0.206、χ²＝0.628、z＝－0.599、z＝－0.031,P均>0.05);两组受者灌注液培养阳性比例及DGF发生率差异均有统计学意义(χ²＝0.031和0.274,P均<0.05)。Logistic回归多因素分析结果显示,灌注液培养阳性是引起肾移植术后感染的独立危险因素(P<0.05)。 结论肾移植受者术后感染发生率较高,感染部位主要为泌尿系统,灌注液培养阳性是肾移植术后感染独立危险因素。     

Urinary N-acetyl-beta-D-glucosaminidase assay in renal transplant recipients.

Urinary N-acetyl-beta-D-glucosaminidase (NAG) activities were measured in 181 patients with renal allografts during a 15-month period. Activities were high immediately after transplantation but decreased rapidly in the absences of complication. Urinary NAG activities increased by 50% or more in relation to 33 of 36 (92%) episodes of acute rejection diagnosed and treated by clinicians during the first 90 days after transplantation. The increase preceded clinical diagnosis in 70% of the cases, the median interval being 1.5 days. NAG activities decreased after treatment of rejection in 90% of the cases. Chronic rejection, renal vein thrombosis, renal artery stenosis, oliguria, hypotension, and the administraion of gentamicin may also cause increased NAG activity. Urinary NAG assay is simple and inexpensive, and is a useful aid to the early diagnosis of rejection of renal transplants. Results must, however, be interpreted by the clinician, bearing in mind other causes for increased activity.     

Fungal infections in renal transplant recipients.

Infection continues to be a major source of morbidity and the major source of mortality in renal transplant recipients who are susceptible to opportunistic infections. We recently reviewed all renal transplant recipients who had fungi cultured during a three year period. C. albicans and T. glabrata were cultured most frequently. Deep fungal infections occurred in many patients and were frequently observed late in the course of bacterial and viral infections. Ten patients had fungemia, and primary fungal pneumonia occurred in eight patients. Three patients had fungal infection of the central nervous system. Three of eight patients with fungal pneumonia and eight of ten patients with fungemia died as a result of their fungus infections. These patients frequently had poor renal function and were receiving high steroid doses or had recently been treated for kidney rejection. One patient with fungal pneumonia and six patients with fungemia had the fungus cultured from a superficial site. Several patients developed fungal infections late in the course of viral or bacterial infections. Amphotericin-B and 5-fluorocytosine remain the mainstays of antifungal therapy.     

Gastroduodenal complications in kidney transplant recipients.

Oral antacids taken every two hours while awake provided the only prophylaxis against gastroduodenal ulceration for 167 kidney transplant recipients between 1968 and July 1978. Either perforation or major hemorrhage occurred in eight patients within 30 days after transplantation. Between July 1978 and January 1981, bleeding occurred within 30 days in two of 147 recipients who were treated with both antacids and cimetidine. Of the 147 patients, eleven with a history of ulcers had undergone pretransplant vagotomy; neither perforation nor hemorrhage occurred in any of the eleven patients. Despite reports that cimetidine enhances certain types of immune responses, we observed slightly greater graft survival in the group treated with cimetidine.     

Intra-abdominal infections in pancreas transplant recipients.

During a 7-year period, 116 pancreas transplants were performed in 98 diabetic patients (49 with and 49 without previous kidney transplants) at the University of Minnesota. The posttransplant clinical course of 26 recipients (22%) was complicated by an intra-abdominal infection (8 with and 18 without previous kidney transplants). Infections occurred in 19/57 cases (33%) in which exocrine secretions were managed by enteric drainage, in 5/15 cases (33%) managed by free drainage into the peritoneal cavity, in 1/39 cases (3%) in which the duct was injected with a synthetic polymer, and in 1/2 cases (50%) in which a pancreaticocystostomy was performed. The organisms Escherichia coli, enterococci, bacteroides, and several anaerobes were cultured from the patients with enteric drainage, while staphylococci were associated with the open duct drainage. Fungal infections with Candida were found with all techniques. Surgical and percutaneous drainage was performed in all patients. In 14 patients, functioning and, in four patients, nonfunctioning grafts were removed. In five patients, the infection resolved while the grafts were functioning, and these patients are currently alive and well. Seven of the 26 patients with infections died (27% mortality rate), five after graft removal and two with the graft still in place (1 with and 1 without function), five in the open-duct, and one each in the enteric and urinary drainage categories. In the 90 cases without intra-abdominal infection, only six patients died (4 cardiovascular, 1 anaphylaxis, 1 cytomegalovirus infection), for a mortality rate of 7%.     

Skin lesions in kidney transplant recipients.

A complete examination of the skin was performed in 53 kidney transplant recipients. Cutaneous lesions were detected in almost all patients. Papillomavirus infections, premalignant and malignant lesions represent the greatest risk for these patients. Our study underlines the importance of a continuous observation to facilitate early diagnosis and treatment of these lesions.     

Humoral immunity in kidney transplant recipients.

Sera obtained from kidney transplant recipients at various times after the graft were investigated for the presence of cytotoxic antibodies to B and T human lymphoid cells and for their ability to inhibit mixed lymphocyte reaction between allogeneic lymphocytes. More than 50% of sera from 35 such patients contained cytotoxic antibodies to B lymphocytes and 27 of 33 sera blocked and miced lymphocyte reaction by 25 to 75%. A statistically significant association between the presence of cytotoxic antibodies to B cells and the ability to block the mixed lymphocyte reaction was found in the group of patients with functioning grafts. However, the presence of cytotoxic antibodies to B lymphocytes did not correlate with the outcome of the graft.     

Urinary tract infections in children with posterior urethral valves after kidney transplantation.

The records of 14 boys with posterior urethral valves who had renal failure and subsequently underwent renal transplantation were reviewed to determine the postoperative incidence of urinary tract infection relative to that of 29 male transplant children without valves, who served as controls. There were no significant differences between the posterior urethral valve patients and controls with regard to age, donor source, immunosuppression, followup after transplantation or mean calculated creatinine clearance. Vesicoureteral reflux was found in 1 child with posterior urethral valves and 3 of the children in the control group (p not significant). A total of 15 urinary tract infections occurred in 5 children (36%) with posterior urethral valves, for a rate of 1 per 30 patient-months of followup, and 6 urinary tract infections occurred in 2 controls (7%), for a rate of 1 per 216 patient-months of followup (p < 0.05). However, only 1 of 26 controls (4%) without vesicoureteral reflux had urinary tract infection, for a rate 1 per 1,144 patient-months (p < 0.01). Conversely, the rate of urinary tract infections in controls with vesicoureteral reflux was similar to that of children with posterior urethral valves. Of the 5 children with posterior urethral valves 4 had the initial urinary tract infection within 2 months of transplantation and 10 of 15 episodes occurred within the first 4 months. Antimicrobial prophylaxis did not appear to decrease the rate of infection in children with posterior urethral valves. A history of posterior urethral valves increases the frequency of urinary tract infection after renal transplantation but the usefulness of antimicrobial prophylaxis and the relationship to long-term graft function remain to be determined. Urinary tract infection rarely develops in other transplanted boys without vesicoureteral reflux.     

Parasitic infections in transplant recipients

Parasitic infections are important complications of organ transplantation that are often overlooked in the differential diagnosis of post-transplantation pyrexial illness. Although their frequency is unknown, they seem to be much less prevalent than bacterial and viral infections. Only 5% of human pathogenic parasites have been reported to cause significant illness in transplant recipients. Infection can occur via transmission with the graft or blood transfusion, or be acquired de novo from the environment. Recrudescence of dormant infection can lead to active disease. Post-transplantation parasitic disorders tend to cluster into two clinical profiles. First, an acute systemic illness with anemia, constitutional manifestations and variable stigmata of organ involvement; acute graft dysfunction can lead to confusion and acute rejection. Protozoa including malarial Plasmodium, Leishmania, Trypanosoma and Toxoplasma are associated with this profile. The second typical manifestation encompasses a few localized syndromes, usually associated with the lower gastrointestinal tract, caused by either protozoa (Cryptosporidium and microsporidia) or nematodes (Strongyloides and Ascaris). Dissemination of localized infections can lead to life-threatening systemic manifestations. A high index of suspicion is essential, as diagnosis requires special sampling techniques and laboratory procedures. Definitive diagnosis is usually achieved by detecting the parasite in the patient's tissues or body fluids by histological examination or culture, or by polymerase chain reaction amplification of the parasite-specific antigen sequence. Antibody detection using serological techniques is also possible in a few parasitic infections. Certain lesions have characteristic radiological appearances, hence the value of imaging, particularly in the cerebral syndromes. Treatment is usually straightforward (broad spectrum or specific drugs), yet some species are drug resistant.     

Urinary tract infections

Urinary tract infections (UTIs) are prevalent and an important topic for the urogynecologist. In this article, we review important definitions, the pathophysiology, and identifiable risk factors for UTI. In addition, the evaluation and management of UTIs is summarized. Finally, attention is focused on UTIs in special populations, including pregnant, hospitalized, and postoperative patients. The latest recommendations from the urologic, infectious disease, gynecologic, and systematic review literature are discussed.     

Urinary calculi in renal transplant recipients

Urinary calculi are an uncommon complication in renal transplant recipients. During a 15-year period, in 544 cases of kidney transplantation with a functioning allograft for more than 3 months, and a long-term follow-up, we have observed 9 cases (1.7%) of urinary calculi. Calculi occurred in 6 male and 3 female patients, 6 patients were recipients of living related and 3 of cadaveric kidneys. Calculi were diagnosed as early as 3 months and as late as 3.5 years after transplantation, but most were detected within the first year. The location of the calculi was the bladder in 4 cases, the transplant in 3, and indeterminant in 2. Crystallographic analysis of retrieved stones revealed calcium oxalate and/or phosphate in 4 cases, triple phosphate in 2, and uric acid in 1. All patients had one or more stone-predisposing factors, such as obstructive uropathy and recurrent urinary tract infection (4 cases), hyperoxaluria (3), or hypercalciuria (2). During long-term follow-up (mean 60 months), only one patient lost the renal graft, 14.5 years after transplantation, primarily from causes unrelated to urinary calculi. One instance of stone recurrence was noted. In conclusion: (1) urinary calculi after renal transplantation are relatively uncommon; (2) predisposing factors and crystallographic composition of the calculi are identical in type, but not frequency, to those of nontransplant patients; and (3) with proper medical and surgical management, post-transplant urolithiasis does not appear to affect graft prognosis.     

Hypertension in kidney transplant recipients

Arterial hypertension is frequently observed in renal transplant recipients. Its pathogenesis is multifactorial in most cases. Calcineurin inhibitors (CNI) can increase peripheral vascular resistance by inducing arteriolar vasoconstriction and can cause extracellular fluid expansion by reducing the glomerular filtration rate (GFR), activating the renin–angiotensin system (RAS), and by inactivating the atrial natriuretic peptide. Glucocorticoids can impair urinary water and salt excretion. Poor graft function can lead to increased extracellular volume and inappropriate production of renin. Native kidneys, older age of the donor and transplant renal artery stenosis (TRAS) may also contribute to the development of hypertension. Arterial hypertension not only can increases the risk for cardiovascular events but can also deteriorate renal allograft function. A number of studies have shown that the higher the levels of blood pressure are, the higher is the risk of graft failure. On the other hand, a good control of blood pressure may prevent many cardiovascular and renal complications. Appropriate lifestyle modification is the first step for treating hypertension. Calcium channel blockers (CCB) and renin–angiotensin system (RAS) inhibitors are the most frequently used antihypertensive agents, but in many cases, a combination of these and other drugs is required to obtain good control of hypertension.