Emerging Landscape of Antibiotic Resistance and Use of Endoscopic Injection in Vesicoureteral Reflux

Vesicoureteral reflux (VUR) in children is often treated with antimicrobials for prolonged durations, which often leads to antimicrobial resistance. In this context, this review article discusses the use of endoscopic injection in VUR as a safe and efficacious option for these children. The literature pertaining to VUR- its clinical manifestation and management, antibiotic resistance- with special reference to management of VUR, and endoscopic dextranomer/hyaluronic acid gel injection for management of VUR was reviewed by identifying key words in a PubMed search. Vesicoureteral reflux is managed using antibiotic prophylaxis, urotherapy, or surgical correction (open, endoscopic injection therapy, or laparoscopic). Continuous antibiotic prophylaxis for urinary tract infections in VUR can lead to antibiotic resistance. Urotherapy cures about 75% of cases with dysfunctional voiding and the rest have to be managed at specialized centers. While open surgery provides relief of VUR and related complications in majority, it requires hospitalization. Endoscopic injection of dextranomer/hyaluronic acid gel into the submucosa of bladder or ureter near ureteral orifice increases the tissue bulk and creates a valve function. Various studies show the efficacy and safety of endoscopic injection of dextranomer/hyaluronic acid gel in VUR. The use of endoscopic injection being a non-invasive modality, can be performed in children with VUR in the outpatient department, precluding hospitalization. In view of the threat of developing antimicrobial resistance and also realising the need for definitive treatment of VUR, endoscopic injection is an efficacious and safe option in primary VUR.

[Urinary tract infections in children]

Urinary tract infections (UTI) are the most common bacterial infections in children. The symptoms are not very specific and range from abdominal pain, poor feeding to nocturnal urinary incontinence. The technique of collecting urine plays an important role for securing the diagnosis. The best way to obtain urine in non-toilet-trained children is catheterization or suprapubic bladder aspiration. In toilet-trained children midstream urine is an acceptable alternative after cleaning the foreskin or labia. In the case of an infection a prompt empirical antibiotic therapy is necessary to reduce the risk of parenchymal scarring of the kidneys. There are different approaches to diagnose vesicoureteral reflux in different countries. The commonly used standard approach in Germany is voiding cystourethrography. In the case of reflux dimercaptosuccinic acid (DMSA) scintigraphy should be performed additionally to exclude renal scarring (bottom-up approach).

Inflammation drives renal scarring in experimental pyelonephritis

Acquired renal scarring occurs in a subset of patients following febrile urinary tract infections and is associated with hypertension, proteinuria, and chronic kidney disease. Limited knowledge of histopathology, immune cell recruitment, and gene expression changes during pyelonephritis restricts the development of therapies to limit renal scarring. Here, we address this knowledge gap using immunocompetent mice with vesicoureteral reflux. Transurethral inoculation of uropathogenic Escherichia coli in C3H/HeOuJ mice leads to renal mucosal injury, tubulointerstitial nephritis, and cortical fibrosis. The extent of fibrosis correlates most significantly with inflammation at 7 and 28 days postinfection. The recruitment of neutrophils and inflammatory macrophages to infected kidneys is proportional to renal bacterial burden. Transcriptome analysis reveals molecular signatures associated with renal ischemia-reperfusion injury, immune cell chemotaxis, and leukocyte activation. This murine model recapitulates the cardinal histopathological features observed in humans with acquired renal scarring following pyelonephritis. The integration of histopathology, quantification of cellular immune influx, and unbiased transcriptional profiling begins to define potential mechanisms of tissue injury during pyelonephritis in the context of an intact immune response. The clear relationship between inflammatory cell recruitment and fibrosis supports the hypothesis that acquired renal scarring arises as a consequence of excessive host inflammation and suggests that immunomodulatory therapies should be investigated to reduce renal scarring in patients with pyelonephritis.

Predictors of Antimicrobial Resistance among Pathogens Causing Urinary Tract Infection in Children

OBJECTIVE

To determine which children with urinary tract infection are likely to have pathogens resistant to narrow-spectrum antimicrobials.

STUDY DESIGN

Children, 2-71 months of age (n = 769) enrolled in the Randomized Intervention for Children with Vesicoureteral Reflux or Careful Urinary Tract Infection Evaluation studies were included. We used logistic regression models to test the associations between demographic and clinical characteristics and resistance to narrow-spectrum antimicrobials.

RESULTS

Of the included patients, 91% were female and 76% had vesicoureteral reflux. The risk of resistance to narrow-spectrum antibiotics in uncircumcised males was approximately 3 times that of females (OR 3.1; 95% CI 1.4-6.7); in children with bladder bowel dysfunction, the risk was 2 times that of children with normal function (OR 2.2; 95% CI 1.2-4.1). Children who had received 1 course of antibiotics during the past 6 months also had higher odds of harboring resistant organisms (OR 1.6; 95% CI 1.1-2.3). Hispanic children had higher odds of harboring pathogens resistant to some narrow-spectrum antimicrobials.

CONCLUSIONS

Uncircumcised males, Hispanic children, children with bladder bowel dysfunction, and children who received 1 course of antibiotics in the past 6 months were more likely to have a urinary tract infection caused by pathogens resistant to 1 or more narrow-spectrum antimicrobials.

[Procalcitonin, a useful biomarker in pediatric urinary tract infection]

Urinary tract infections (UTIs) are one of the most common sources of bacterial infections among young febrile children. Accurate diagnosis of acute pyelonephritis (APN) and vesico-ureteral reflux (VUR) are important because of their association with renal scarring, sometimes leading to long-term complications. However, the gold standard examinations are either a DMSA scan for APN and scarring, or cystography for VUR, but both present limitations (feasibility, pain, cost, etc.). Procalcitonin, a reliable marker of bacterial infections, was demonstrated to be a good predictor of renal parenchymal involvement in the acute phase and in late renal scars, as well as of high-grade VUR. These findings need further broad validations and impact studies before being implemented into daily practice. However, procalcitonin may play a role in the complex and still debated picture of which examination should be performed after UTI in children.

Predicting factors of breakthrough infection in children with primary vesicoureteral reflux

PURPOSE

Many pediatric urologists still favor using prophylactic antibiotics to treat children with vesicoureteral reflux (VUR). However, breakthrough infection sometimes occurs, leading to significant increases in morbidity as a result of renal scarring. Therefore, we tested whether abnormal renal scan and other factors are predictive of breakthrough infection using univariate analyses.

MATERIALS AND METHODS

We retrospectively reviewed the medical records of 163 consecutive children who were diagnosed with vesicoureteral reflux between November 1997 and June 2010. Clinical parameters for the statistical analysis included form of presentation, gender, age, VUR grade, laterality, presence of intrarenal reflux, class of antibiotic drug, and presence of abnormal renal scan by Dimercapto-succinic acid. Clinical parameters used for prognostic factors were established by univariate analyses. Fisher's exact test and unpaired t-test were done using SPSS software [SPSS ver. 12.0 (SPSS Inc., Chicago, IL, USA)].

RESULTS

Breakthrough infection developed in 61 children (48.0%). A total of 58 children (45.7%) had abnormal renal scans. Time to development of breakthrough infection was significantly longer in girls (9.0±8.2 months) than in boys (5.8±4.8 months, p<0.05). On univariate analysis, though statistically not significant, the most predictive factor of breakthrough infection was abnormal renal scan (p=0.062). In patients with abnormal renal scans, breakthrough infection was not associated with mode of presentation, gender, grade or prophylactic antibiotics. However, there was a significant difference between patients younger than 1 year and those 1 year old or older. Mean±SD age at diagnosis of VUR in patients with breakthrough infection (1.14±3.14) was significantly younger than in those without breakthrough infection (5.05±3.31, p=0.009). There was also a significant difference between patients with bilateral or unilateral reflux (p=0.028).

CONCLUSION

Our data showed that abnormal renal scan was the most predictive factor of breakthrough infection and demonstrated statistical significance in patients under the age of 1 year. Parents and physicians should remain aware that these patients are at high risk of breakthrough urinary tract infection, which may potentially lead to renal damage.

Part 1: Vesicoureteral reflux treatment: the past, present, and future

The purpose of this manuscript is to provide clinicians with highlights of key findings pertaining to our current understanding and treatment of the condition of vesicoureteral reflux (VUR). This includes a review of the disease, patient characteristics, current treatment options, challenges for managed care and patients, and opportunities for improvements in care. This is not intended as a comprehensive review of VUR. This manuscript does, however, serve to introduce three additional manuscripts contained within this supplement. The first article in this series is designed to provide the clinician with real-world data pertaining to treatment patterns and outcomes in patients with VUR (Examining pediatric vesicoureteral reflux: a real-world evaluation of treatment patterns and outcomes: Hensle TW, Hyun G, Grogg AL, Eaddy M). The second article considers the efficacy of prophylactic antibiotics in reducing the likelihood of urinary tract infections (UTIs) when compared with endoscopic injection with dextranomer/hyaluronic acid (Endoscopic injection versus antibiotic prophylaxis in the reduction of urinary tract infection in patients with vesicoureteral reflux: Elder JS, Shah MB, Batiste LR, et al.). The third article explores the role medication noncompliance plays in contributing to antibiotic resistance, the consequences associated with resistance (longer lasting illness and costs), and the difficulties with resistance specific to UTI pathogens in children (Considerations regarding the medical management of VUR: what have we really learned?: Koyle MA, Caldamone A). This supplement is intended to provide the clinician with valuable information regarding the treatment patterns, the role of compliance, and the efficacy of treatments for pediatric patients with VUR.

Renal Scarring in Familial Vesicoureteral Reflux: Is Prevention Possible?

PURPOSE

Detailed knowledge about risk factors for renal scarring in familial reflux is necessary to decide whether these factors could be influenced by early screening and treatment of siblings. We evaluated the prevalence of and risk factors influencing renal scarring in familial vesicoureteral reflux.

MATERIALS AND METHODS

We reviewed the medical records and dimercapto-succinic acid scans of 306 children with familial vesicoureteral reflux. Scarring was classified as mild, moderate and severe. The impact of urinary tract infections, patient sex, reflux grade and age at diagnosis on renal scarring was evaluated.

RESULTS

The prevalence of renal scarring was identical at 36% in 142 index patients and 74 siblings presenting with urinary tract infection but it was only 10% in 87 asymptomatic siblings (p <0.001) The difference between siblings with and without urinary tract infection was only statistically significant for mild scarring (23% vs 4.6%, p <0.001). It did not attain significance in those with moderate to severe scarring (13.5% vs 5.7%). Moderate to severe scarring was significantly more common in grade V than in grade IV refluxing units (43% vs 10%, p <0.0001) and in male than in female siblings (15.8% vs 3.4%, p = 0.012). Mild scarring was not significantly associated with reflux grade or patient sex. Children diagnosed before age 3 years showed significantly less scarring than patients diagnosed later (23% vs 41%, p <0.002).

CONCLUSIONS

The development of mild renal scarring seems to mainly depend on urinary tract infections, while moderate and severe scarring are also associated with high grade reflux and male sex. Early detection and treatment may prevent further urinary tract infections as well as reflux related kidney damage.

Acute urinary tract infection--evaluation and treatment

PURPOSE OF REVIEW

The evaluation and management of urinary tract infections in infants and children is undergoing changes due to the impact of evidence-based studies and new technology.

RECENT FINDINGS

The uncircumcised male infant is at increased risk for a urinary tract infection, but there is marked difference in the frequency of circumcision carried out to lower the risk of infection in the United States compared with Europe. Commentaries presenting different interpretations of the current data make for interesting reading and present the many sides of this issue. Vesicoureteric reflux, previously viewed as the major risk factor for acquired renal damage, now shares this role with nonreflux nephropathy. Procalcitonin has been evaluated as a biochemical tool to identify patients at risk for kidney damage, with dimercaptosuccinic acid scintigraphy as the reference method to detect renal scarring.

SUMMARY

The previously accepted concept that vesicoureteric reflux as detected radiologically is almost always the key factor in acquired renal injury secondary to a urinary tract infection is no longer accepted. Current studies show that nonreflux nephropathy occurs as often as reflux nephropathy. There is now a question of the value of imaging studies designed to identify vesicoureteric reflux and of the use of suppressive antibiotics for vesicoureteric reflux. There exist useful evidence-based studies for antibiotic therapy for upper and lower tract urinary tract infections, but no such data are available for guidance in selecting imaging studies for the infant or child with a first febrile urinary tract infection.

Evaluation of the use of DMSA in culture positive UTI and culture negative acute pyelonephritis

This prospective study was done to assess the frequency of acute pyelonephritis (APN) in febrile children with positive urine culture as documented by Tc99m DMSA scintigraphy (DMSA) and the frequency of vesicoureteric reflux (VUR) in these children. Secondly, to determine the frequency of APN, in febrile children with supportive evidence for UTI but with negative urine culture, as documented by DMSA and frequency of VUR in them. Thirdly to stress the utility of DMSA to diagnose APN in urine culture negative febrile children and to suggest DMSA as a clinical tool in evaluation of fever of unknown origin (FUO). This study included 42 children with positive urine culture and 26 children with negative urine culture who had supportive evidence of UTI as determined by the predetermined criteria and diagnosed to have APN by DMSA. All of them had ultrasonogram (USG), DMSA and voiding cystourethrogram (VCU). They were followed up for a minimum period of 6 months. Out of the 42 children with positive urine culture 92.9% had features of APN in the DMSA of whom 82.1% had vesicoureteric relux (VUR). The DMSA was abnormal in 26 children with negative urine culture, of whom 65.4% had VUR. Ultrasound suggestive of parenchymal change was observed in 47.6% in the culture positive group and 65.4% in the culture negative group. In conclusion, it is suggested, that DMSA is a useful investigation for the diagnosis of APN in febrile UTI. DMSA is indicated in febrile children with negative urine culture but with supportive evidence of UTI and in FUO. An abnormal DMSA is a strong indication for work up for VUR.

ACE gene polymorphism and renal scar in children with acute pyelonephritis

The pathogenesis of renal scarring after acute pyelonephritis (APN) in children is multifactorial. In addition to well-known risk factors (young age, high grade of vesicoureteral reflux, P-fimbriated Escherichia coli, and treatment delay), a role for genetic predisposition has been suggested. Since the ACE gene deletion polymorphism is a known risk factor for progressive glomerulosclerosis in chronic renal diseases, we have investigated the relationship between the ACE genotypes and the development of renal scarring after APN. Fifty-nine children (43 males and 16 females) with APN diagnosed by urine culture and technetium-99m-dimercaptosuccinic acid ((99)Tc-DMSA) renal scan were studied. ACE genotypes were determined as II, ID, and DD using the polymerase chain reaction technique. A follow-up (99)Tc-DMSA renal scan was performed to evaluate the development of renal scars 3-6 months after treatment. The distribution of ACE genotypes and the allele frequencies were compared in the renal scar-positive ( n=39) and -negative group ( n=20). ACE genotype frequency after stratification by risk factors was also evaluated. The distribution of ACE genotypes did not differ between the renal scar-positive (II 25.9%, ID 35.9%, DD 28.2%) and -negative group (II 35.0%, ID 45.0%, DD 20.0%), before and after stratification by each risk factor. ACE gene deletion polymorphism did not affect the development of renal scar as an independent variable in children with APN.

Renal scarring caused by vesicoureteric reflux and urinary infection: a study in pigs

The diminishing risk of acute renal scarring with urine infections (reflux nephropathy) after infancy is unexplained, but might reflect kidney maturation. The mechanisms of reflux nephropathy scarring are best explained by a piglet model in which vesicoureteric reflux allows infected urine to enter those segments of renal parenchyme that are drained by compound papillae. We carried out a similar study in adult pigs to determine whether protective maturation occurs. Adult pigs were exposed to urine infection after surgery to produce unilateral vesicoureteric reflux. The intravesical portion of one ureter was deroofed in six female adult Gottingen mini-pigs and the bladder and the ureteric mucosae stitched around the perimeter of the new orifice. One week later Escherichia coli was injected into the urinary bladder to produce cystitis. Three weeks later the animals were killed humanely and the urinary tracts were examined. The animals sustained persistent urine infections; the untreated ureters and kidneys remained normal. However, on the operated side, the ureters were thickened and dilated, vesicoureteric reflux was shown in four cases, and the kidneys had one or more flattened area overlying a renal segment, which showed severe inflammatory changes and early scar formation. The risk of reflux nephropathy scarring is not eliminated by maturation of the kidney in pigs. It is unlikely that the much-reduced risk of initiating scarring that is seen in older children with urine infections is due to a protective maturation of the human kidney. A possible explanation is that most children born with risk factors for developing scarring will have already sustained scars when very young.

Acute renal damage in infants after first urinary tract infection

Urinary tract infection (UTI) is one of the most common causes of unexplained fever in neonates. The aim of this study was to determine the incidence of urinary tract anomalies and acute renal damage in neonates who presented with first urinary tract infection in the first 8 weeks of life. We reviewed the records of 95 infants, who were hospitalised with UTI during a 6-year period (1994-1999). Patients with antenatally diagnosed hydronephrosis and incomplete radiological investigations were excluded from the study. Of the remaining 57 patients, 42 were boys and 15 girls. The mean age at diagnosis was 32 days (range 5-60 days). All patients underwent renal ultrasonography (US), voiding cystourethrogram (VCUG) and (99m)Tc-dimercaptosuccinic acid (DMSA) scan. Urinary tract abnormalities were detected in 20 (35%) patients. Vesicoureteral reflux (VUR) was found in 19 (33%) neonates, 7 girls and 12 boys. Acute cortical defects on DMSA scan were present in 19 kidneys of patients with VUR and in 25 of those without reflux. Only one-third of neonates after first symptomatic UTI had VUR. We recommend that US, VCUG, and DMSA scan should be routinely performed after the first UTI in infants younger than 8 weeks.

[Bilateral nephrectomy as a life saving procedure in a young woman with recurrent bacteremic shock]

On the basis of the recurrent bacteremic shock in young woman with bilateral reflux nephropathy and recurrent urinary tract infections (UTI) from early childhood we present diagnostic and therapeutic problems of complicated UTI. Negative results of localization diagnosis of UTI and clinical suspicious on renal microabscesses as a cause of recurrence bacteremic shock were the reason of bilateral nephrectomy--as a life saving procedure--and initiation of CAPD programme.

Children's UTIs in the new millennium. Diagnosis, investigation, and treatment of childhood urinary tract infections in the year 2001

OBJECTIVE

To provide an effective approach for family physicians treating children presenting with urinary tract infections (UTIs).

QUALITY OF EVIDENCE

The information presented, and articles quoted, are drawn from both review of the literature and recent consensus guidelines. Data and recommendations come from prospective multicentre trials; retrospective reviews; expert consensus statements; and some smaller trials, commentaries, and editorials.

MAIN MESSAGE

Urinary tract infections are often seen in family practice. Diagnosis requires suspicion and a realization that children, especially those younger than 2 years, often have very few, nonspecific signs of infection. Obtaining a proper urine sample is vital, because true infections require radiographic studies. Antibiotic prophylaxis is promoted because of the link between vesicoureteral reflux, recurrent UTIs, and renal scarring and hypertension. We generally provide prophylaxis until children are 3 or 4 years, when risk of damage from reflux is lessened and timely urine samples are easier to obtain for prompt therapy. Surgical opinion is sought only when medical management has failed. Failure is defined as either recurrent infections and pyelonephritis or poor renal growth.

CONCLUSION

To diagnose UTIs in children, physicians must suspect them, obtain proper urine samples, order appropriate investigations to rule out underlying anatomic abnormalities, and treat with appropriate antibiotics considering both organism sensitivities and length of therapy.

Urinary tract infection in children: a review of its pathogenesis and risk factors

Urinary tract infection (UTI) is one of the commonest bacterial infections seen in children, ranking second only to those of the respiratory tract. A steady flow of urine, complete emptying of the bladder and various host defences provide the principal means of protection. Urinary stasis, on the other hand, provides an opportunistic environment for bacterial multiplication; several other factors also contribute to UTI, such as urinary obstruction, vesico-ureteric reflux (VUR) and other urinary tract malformations. UTI, especially in the presence of VUR, may lead to scarring of the kidney and progressive renal disease. It is vital, therefore, to diagnose such anomalies at an early stage, the overall aim being to identify those at high risk so that measures may be taken to prevent serious complications and preserve renal function. Those at low risk of UTI, however, should not be over investigated; this is in order to keep invasive procedures down to a minimum. Whenever possible, the management of high risk cases is best discussed between paediatrician, microbiologist, radiologist, urologist and the general practitioner.

[Bacterial flora of the urinary tract and its drug sensitivity in children with vesico-ureteral reflux]

The authors of the following publication present the results of a research which has been made on the presence of bacterial flora in children with vesico-ureteral reflux. As a first step, an analysis of the bacterial flora was made. Then, two pathogens occurring most often were selected their drug-sensitivity was tested. The assessment of the bacterial flora and its drug-sensitivity ware based on urine inoculations. Clinical material was provided by 184 children suffering from urinary tract infections, out of whom only those with the vesico-ureteral reflux diagnosed on the basis of miction ureterography, were taken into consideration. In the wake of the analysis made, E. coli, which causes 30% of the infections, and Enterococcus fecalis, causing 14% of the infections, were found out to be the pathogens occurring most often in urine cultures. Other bacteria, listed according to the occurrence rate, are as follows: mixed flora, Streptococcus spp, Proteus mirabilis, Staphylococcus epidermidis, Klebsiella pneumoniae. As regards drug-sensitivity, E. coli & Enterococcus fecalis have been considered to reveal the same high sensitivity to nitrofurantoin and 3-generation cefalosporyn.

Adjunctive oral corticosteroids reduce renal scarring: the piglet model of reflux and acute experimental pyelonephritis

PURPOSE

We investigate the efficacy of antibiotics combined with corticosteroid in diminishing post-pyelonephritic renal scarring compared to standard antibiotic therapy.

MATERIALS AND METHODS

Bilateral vesicoureteral reflux was surgically created in 36 piglets (72 kidneys). A week later each bladder was inoculated by percutaneous injection with a standardized broth culture of Escherichia coli and molten paraffin. 99mTechnetium dimercapto-succinic acid (DMSA) scintigraphy was performed 3 days after introduction of urinary infection to detect the presence of acute pyelonephritis. Acute pyelonephritic lesions seen on DMSA scans were graded according to the percentage of renal zone involvement as grade 1--less than 33%, grade 2--33 to 66% and grade 3--greater than 66% involved. When pyelonephritis was present, piglets were randomized to receive either standard antibiotics or antibiotics and 2 mg./kg. prednisolone daily. 99mTechnetium-DMSA scintigraphy was repeated 2 months after completion of therapy, and the kidneys were harvested for gross and histopathological examination. Each kidney was divided into upper, middle and lower zones for correlation of pathological and imaging findings. Severity of renal scarring was then assessed using histopathological confirmation of gross anatomical findings as grade 1--less than 1, grade 2-1 to 2 and grade 3-greater than 2 cm.

RESULTS

Acute pyelonephritis was induced in 136 of 216 renal zones. The sites of renal scarring corresponded anatomically to sites of acute pyelonephritis in all but 5 cases. Overall, the prevalence of post-pyelonephritic scarring was 56.6% (77 of 136) of renal zones. The severity of scarring in both groups correlated with the severity of the initial pyelonephritic lesion. Of the 31 zones that formed grade 3 renal scars the distribution of grades 1, 2 and 3 acute pyelonephritis on the initial DMSA scan was 3, 26 and 71%, respectively. Grade 3 acute pyelonephritis was more likely to result in severe (grade 3) renal scars in the control compared to the steroid treated group (59 versus 31%). Overall, acute pyelonephritis completely resolved in 40% of controls and 51% of steroid treated animals. However, only 9% of control animals with grade 3 acute pyelonephritis demonstrated complete resolution, as opposed to 28% of those receiving steroids.

CONCLUSIONS

The risk of renal scarring is greatest after severe acute pyelonephritis involving greater than 66% of a renal zone. Adjunctive oral prednisolone appears to be effective in diminishing renal scarring in severely affected kidneys. In kidneys with mild and moderate acute pyelonephritis antibiotics alone appear to be equally effective in preventing scarring.

Low bacterial counts in infants with urinary tract infection

We analyzed the number of colony-forming units in urine cultures obtained by suprapubic aspiration in a group of 366 unselected infants with symptomatic urinary tract infection to relate these findings to factors such as pyuria and vesicoureteric reflux. Seventy-three (20%) of 366 infants had fewer than 100,000 colony-forming units per milliliter. Such low counts were significantly related to low numbers of leukocytes in the urine. Vesicoureteric reflux was equally distributed among children, irrespective of the number of bacteria in quantitative culture. The findings emphasize the importance of sampling technique; in infants, the method of choice is suprapubic aspiration, or catheterization, which eliminates the risk that urinary tract infection is overlooked because of low bacterial counts.

Update on dimercaptosuccinic acid renal scanning in children with urinary tract infection

The dimercaptosuccinic acid (DMSA) renal scan is a method for assessing kidney function. Indications for DMSA scanning in children with urinary tract infection (UTI), as well as timing, have changed. Pitfalls in interpreting DMSA scans include: (1) acute pyelonephritis (APN), (2) tubular dysfunction, (3) hypertension, (4) use of captopril in patients with renovascular hypertension and (5) duplex kidneys. Interpretation of DMSA scans in children with UTI vary according to timing and clinical setting. During the course of a febrile UTI a DMSA scan may reveal a normal kidney, APN or a non-functioning, small and/or ectopic kidney. In the absence of UTI (up to 6 months) in children with vesicoureteric reflux a DMSA scan may indicate a normal kidney, renal scarring (reflux nephropathy), occult duplex kidney and allows the progression of scarring and hypertrophy of normal areas of the kidney to be followed anatomically. The DMSA renal scan in now the most reliable test for the diagnosis of APN. The transient abnormalities due to APN can occur in normal or scarred kidneys. Lesions due to reflux nephropathy (defined as a defect in the renal outline or contraction of the whole kidney) are permanent. Intravenous urography reveals renal abnormalities later than the DMSA scan. If abnormalities are seen on a DMSA scan performed during the course of APN it is impossible to predict the outcome: they can progress to permanent scarring or heal completely. An abnormal DMSA scan during a febrile UTI allows the identification of children at risk of developing renal scars. These children should be carefully investigated, maintained on long-term quimioprophylaxis and followed.

The intravenous urogram in the detection and evaluation of renal damage following urinary tract infection

Intravenous urography (IVU) still provides the most comprehensive structural assessment of the urinary tract. In particular, the radiological renal appearances approximate closely to the morphology of the renal scarring of reflux nephropathy or chronic atrophic pyelonephritis. It also provides reproducible renal measurements for follow-up assessment of renal growth and scarring. It is now less often used for first-line investigation of the acute urinary tract infection (UTI) because the swelling accompanying acute renal involvement is less easily recognised than the areas of defective function demonstrated on 99mtechnetium-dimercaptosuccinic acid (DMSA) studies. Also IVU contributes a higher radiation dose when calculated for full IVU (dependent on the number of films exposed) and there is a slight risk of side effects from injected contrast media, reduced by using non-ionic compounds. Because of its value in confirming such a serious diagnosis as renal scarring, suspected on ultrasonography or DMSA scintigraphy, modification of the technique of IVU with adequate preparation and the use of a reduced number of films, or single films localised to the renal areas, should be considered. Expertise in the interpretation of IVU must also be maintained because of the ancillary information regarding bowel and bladder function, the spine and evidence of stones, pertinent to the management of children with UTI and renal scarring. IVU and DMSA study remain complementary investigations.

Enterocystoplasty and reflux nephropathy in the canine model

Correction of vesicoureteral reflux at enterocystoplasty is often recommended to prevent the development of reflux nephropathy. Children with enterocystoplasty who require intermittent self-catheterization invariably have asymptomatic bacteriuria. In patients with persistent vesicoureteral reflux after enterocystoplasty the risk of renal damage from this asymptomatic bacteriuria is unknown. Detubularized ileocystoplasty was performed in 17 dogs with either direct nontunneled reimplantation or unroofing of the intramural tunnel and incision of the ipsilateral hemitrigone to create vesicoureteral reflux. Fluoroscopic urodynamic studies were performed 1 month later and unilateral vesicoureteral reflux was present in 6 dogs. All animals had low intravesical pressure and excretory urograms were performed to exclude obstruction. The 6 dogs with reflux were euthanized 3 months postoperatively and the kidneys were examined for histological evidence of pyelonephritis. In 5 of 6 dogs bacterial bladder colonization and subsequent renal pelvic colonization developed on the side of the vesicoureteral reflux. All of these animals had histological evidence of pyelonephritis in the refluxing kidney, whereas only 1 of 6 nonrefluxing control kidneys had any evidence of pyelonephritis (p = 0.031). Our results suggest that vesicoureteral reflux in association with enterocystoplasty leads to chronic upper tract infection and pyelonephritis in a majority of animals, despite creation of a low pressure urinary reservoir. Correction of vesicoureteral reflux at enterocystoplasty should be considered to prevent upper tract damage.

[Correlation of vesico-ureteral reflux and recurrent urinary tract infections with increased bacterial adherence]

Unimpeded urinary flow and voiding of the bladder without residual urine are essential for the prevention of urinary tract infections. Therefore, recurrent urinary tract infections are most commonly found in patients with functional and anatomic disorders of the urinary tract. Children suffering from vesico-ureteral reflux are especially susceptible to recurrent urinary tract infections. The interaction between germ and target cell, i.e. between antigen and receptor, is another important factor in the development of urinary tract infections. This so-called bacterial adherence is variable and depends upon receptor density as well as the affinity of the germ to the receptor. However, our study showed that this bacterial adherence plays a minor role in the development of recurrent urinary tract infections secondary to vesico-ureteral reflux.

Biochemical fingerprinting of urinary Escherichia coli causing recurrent infections in women with pyelonephritic renal scarring

A biochemical fingerprinting system, especially designed for subtyping of Escherichia coli and suitable for screening large number of bacterial strains was used in a long-term follow-up study of 19 women with non-obstructive pyelonephritic renal scarring and recurrent urinary infections in order to examine whether recurrent infections mostly are relapses or reinfections in this group of patients. Seventy-six recurrent infections occurred during a 47-month follow-up (0.09 infections per observation month). The majority of the recurrences were reinfections (58/76, 76%) and 18 (24%) were relapses caused by E. coli. Approximately 50% of relapses and reinfections caused by E. coli were symptomatic while the majority of reinfections caused by other bacteria were asymptomatic (23/30, 77%). In one patient a relapse of E. coli infection occurred more than two years (745 days) after the initial infection. Reinfections may occur early (7 days) after cessation of antimicrobial therapy in this group of patients. Two patients had an episode of symptomatic bacteriuria 51 and 56 days after asymptomatic bacteriuria with the same E. coli strain was detected. Biochemical fingerprinting of the E. coli isolates revealed that they belong to a wide variety of biochemical phenotypes which indicates that they are not members of widespread uropathogenic clones.

Clean, intermittent catheterization of infants with neurogenic bladder

Clean, intermittent catheterization was instituted in 38 babies with myelodysplasia who were thought to be at risk for upper urinary tract deterioration because of neurogenic bladder dysfunction. There were 19 patients 2 weeks to 12 months of age, 11 were 1 to 2 years of age, and 8 were older than 2 years. Effectiveness of clean, intermittent catheterization was determined by maintenance of upper urinary tract stability. Upper urinary tracts improved or remained stable in 13 of 16 infants (81%) with reflux and 16 of 18 infants (89%) with detrusor-sphincter dyssynergia. Bacteriuria was present in 16 (42%), with only 2 infants (5%) having a febrile episode; no infant required hospitalization because of urinary tract infections. No further complications were identified in infants who were cleanly and intermittently catheterized. Most families found clean, intermittent catheterization of their infants easy to master and not stressful, and their children adjusted to it at an early age.

Molecular epidemiology of adhesin and hemolysin virulence factors among uropathogenic Escherichia coli

The pap, prs, pil, and hly operons of the pyelonephritic Escherichia coli isolate J96 code for the expression of P, F, and type 1 adhesins and the production of hemolysin, respectively; the afaI operon of the pyelonephritic E. coli KS52 encodes an X adhesin. Using different segments of these operons as probes, colony hybridizations were performed on 97 E. coli urinary tract and 40 fecal clinical isolates to determine (i) the presence in the infecting bacteria of nucleotide sequences related to virulence operons, and (ii) the phenotypic properties associated with such sequences. Coexpression of P and F adhesins encoded by pap-related sequences was detected more frequently among isolates from patients with pyelonephritis (32 of 49, 65%) than among those with cystitis (11 of 48, 23%; P less than 0.0001) or from fecal specimens (6 of 40, 15%; P less than 0.0001). Therefore, the expression of both adhesins appears to be critical in the colonization of the upper urinary tract. In contrast, afaI-related sequences were detected significantly more frequently among isolates from patients with cystitis, suggesting that this class of X adhesin may have a role in lower urinary tract infections. Urinary tract isolates differed from fecal isolates by a low incidence of type 1 adhesin expression among pil probe-positive isolates. hly-related sequences were only detected in pap probe-positive isolates. The frequency of hemolysin production among pap probe-positive isolates was not associated with a particular pattern of infection. The distribution of these virulence factors was similar in the presence or absence of reflux, indicating that structural abnormalities of the urinary tract did not facilitate colonization by adhesin-negative isolates.

An electron microscopic study of pathogenesis of urinary tract infection caused by Pseudomonas aeruginosa P 9 in mice

Scanning and transmission electron microscopic examination of the kidney and bladder of mice infected transurethrally with Pseudomonas aeruginosa P 9 revealed that the pyelonephritis is established through two routes, after the organisms reach the pelvis of the kidney via the bladder and ureter. In one route, which appeared to be predominant, the inoculated bacteria invaded the renal parenchyma through exfoliation of the calyceal epithelial cells with subsequent destruction of the basement membrane. Alternatively, the inoculated bacteria retrograded in the collecting tubules and urineferous tubules and propagated in the lumina followed by invasion of the renal parenchyma. In the bladder, the inoculated bacteria increased in number then disappeared within 48 h after exhibiting morphological aberrations such as elongation, bulge and spheroplast formation.

Association of P and other fimbriae with clinical pyelonephritis in children

196 episodes of urinary tract infection in children were analysed. 74 were classified as pyelonephritic (PN), 61 as cystitis (C), and 61 as asymptomatic bacteriuria (ABU) on the basis of three clinical signs (elevated temperature, erythrocyte sedimentation rate, and/or white blood cell count). The frequency of P-fimbriae was found high in PN (77%), and significantly lower in C (23%), ABU (20%) and among fecal strains (16%). The common, type 1 fimbriae were also more frequent in PN (92%) than in the other groups (84-76%), whereas other, so-called X-fimbriae, were relatively rare in all the patient groups (15-6%). P-fimbriation was not significantly associated with the presence or absence of reflux or obstructive anomalies. By contrast, the frequency of P-fimbriation increased with increasing severity of the clinical symptoms of pyelonephritis (95% in episodes of elevated temperature, erythrocyte sedimentation rate and white blood cell count).

P-fimbriae of pyelonephritogenic Escherichia coli: significance for reflux and renal scarring-a hypothesis

An experimental pyelonephritis model was developed in monkeys (Macaca fascicularis) using P-fimbriated Escherichia coli as the infecting organism. The relevant receptor molecules for P-fimbriae were also shown to be present in Macaca fascicularis. Atraumatic administration of P-fimbriated E. coli into the ureter induced a ureteritis followed by acute and chronic pyelonephritis. The decisive role of P-fimbriae as an adhesive virulence factor was proven by the receptor blockade of P-fimbriae-mediated bacterial adhesion by a synthetic receptor analogue (alpha-D-Galp-(1-4)-beta-D-Galp-1-OMe), which was administered into the ureter together with the challenge bacteria. On the basis of these and other findings, the role of reflux and pyelonephritis in relation to renal scarring is discussed in this paper. It is proposed that minor transitional vesicoureteral reflux together with the adhesive property of P-fimbriated E. coli and their ability to induce ureteritis might constitute an alternative mechanism to gross reflux by which bacteria ascend to the kidney. These findings and the fact that intestinal colonization with P-fimbriated E. coli coincides with the disease have opened up new prophylactic and therapeutic possibilities.

Ureaplasma urealyticum in the upper urinary tracts of renal allograft recipients

Urine samples from 123 renal transplant recipients were cultured for the presence of Ureaplasma urealyticum and other fastidious microorganisms. Ureaplasmas were recovered alone or in association with other microbial species from the bladder urine of 13 (11%) of the 123 patients, and evidence of involvement of the upper urinary tract was present in nine patients. Colonization of the upper urinary tract by U. urealyticum was not associated with a decline in function of the grafted kidney and was found only in patients with a primary diagnosis of reflux nephropathy (50% of such patients were positive for ureaplasmas) or glomerulonephritis (10% were positive) who had their own kidneys. The next most common isolate was Gardnerella vaginalis, recovered from 7% of patients, the majority of whom harbored the organism in the bladder only. The results confirm that U. urealyticum may colonize the upper urinary tracts of patients with proven renal disease.

[Recurrent bacteriuria in children]

Fifty-four children admitted to the Children's Hospital of Cordoba City with recurrent bacteriuria were followed for 12 to 97 months. Most of them were females and Escherichia coli was the most frequent microorganism isolated in recurrent attacks of bacteriuria. Ninety percent of the patients showed urological abnormalities. Vesicoureteral reflux was the most frequent. Residual urine was considered the main cause of recurrent bacteriuria. After antibioticotherapy and surgical treatment, over one half of the patients persisted with relapses. Recurrent bacteriuria appeared more frequently in male infants with severe urologic abnormalities. Finally, three groups of patients in relation to uropathy and functional renal impairment are described and a different prognosis for each one is proposed. For this reason, each patient must have a complete urologic examination done at the onset and a carefull follow-up, carried out.

The absence of vesicoureteral reflux in the neonate with myelodysplasia

Urologic evaluation of 21 newborns with myelomeningoceles revealed a rarity of infection and an absence of vesicoureteral reflux on cystourethrography. An hypothesis has been advanced to explain the absence of reflux and the high incidence of reflux reported in older children with myelomeningoceles. The absence of reflux in these neonates indicates that reflux in children with myelomenigoceles is not caused by a primary congenital ureterovesical junction abnormality but rather is secondary to infection and/or progressive bladder dysfunction.

[Vesico-renal reflux in adults (author's transl)]

This article is based on an analysis of 88 cases of vesico-renal reflux, 43 primary and 45 secundary ones. The author consider successively the clinical, bacteriological, radiological and endoscopical facts and their relations to the different types of reflux. They emphasize the frequency and the gravity of the primary reflux in adults and its probable connection with the genesis of the non-obstructive pyelonephrities and the unilateral renal atrophies. Its noxioness is primarily connected with the infection. The secundary reflux, however, even infected, is relatively well tolerated in adults. In case of primary vesico-renal reflux the therapeutical conduct has to be extremely well suited. A surgical correction should only be considered if the kidney has satisfactorily maintained its fonction and if the tonicity of the excreting ways is still good enough. In case of secundary reflux, the therapeutical conduct depends first of all on the etiology. In the group of primary reflux 11 patients derived benefit from ureteral reimplantation; whereas in the group of secundary reflux only 5 patients were submitted to an operation. The method applied was that of Paquin.