Clinical pyelonephritis and focal renal scarring. A selected review of pathogenesis, prevention, and prognosis

Complete Remission of Renal Scarring in Follow-Up DMSA Renal Scintigraphy After Urinary Tract Infection

Our study aimed to investigate the association between the characteristics of patients/images and complete remission of renal scarring shown in the first chronic phase Technetium-99m dimercaptosuccinic acid (DMSA) renal scintigraphy images in children with urinary tract infection (UTI). Fifty children, who underwent the chronic phase of DMSA scintigraphy more than twice following UTI diagnosis and had renal scarring in the first chronic phase DMSA renal scintigraphy, were enrolled. They were classified into 2 groups: with and without complete remission of renal scarring on the second chronic phase DMSA renal scintigraphy. Renal scarring was classified into 3 grades based on severity per the image findings. Seven cases had complete remission from renal scarring. There were significant differences in age and severity. Renal scarring might be completely reversed in young children without severe findings on DMSA renal scintigraphy. Additional chronic phase examination may aid in follow-up completion and patients' peace of mind.

Validity of bag urine culture for predicting urinary tract infections in febrile infants: a paired comparison of urine collection methods

Purpose

Catheter urine (CATH-U) and suprapubic aspiration (SPA) are reliable urine collection methods for confirming urinary tract infections (UTI) in infants. However, noninvasive and easily accessible collecting bag urine (CBU) is widely used, despite its high contamination rate. This study investigated the validity of CBU cultures for diagnosing UTIs, using CATH-U culture results as the gold standard.

Methods

We retrospectively analyzed 210 infants, 2- to 24-month-old, who presented to a tertiary care hospital's pediatrics department between September 2008 and August 2013. We reviewed the results of CBU and CATH-U cultures from the same infants.

Results

CBU results, relative to CATH-U culture results (≥10⁴ colony-forming units [CFU]/mL) were widely variable, ranging from no growth to ≥10⁵ CFU/mL. A CBU cutoff value of ≥10⁵ CFU/mL resulted in false-positive and false-negative rates of 18% and 24%, respectively. The probability of a UTI increased when the CBU bacterial count was ≥10⁵/mL for all infants, both uncircumcised male infants and female infants (likelihood ratios [LRs], 4.16, 4.11, and 4.11, respectively). UTIs could not be excluded for female infants with a CBU bacterial density of 10⁴-10⁵ (LR, 1.40). The LRs for predicting UTIs based on a positive dipstick test and a positive urinalysis were 4.19 and 3.11, respectively.

Conclusion

The validity of obtaining urine sample from a sterile bag remains questionable. Inconclusive culture results from CBU should be confirmed with a more reliable method.

Increasing antibiotic resistance among uropathogens isolated during years 2006-2009: impact on the empirical management

Urinary tract infections (UTI) are one of the most common infections with an increasing resistance to antimicrobial agents.

PURPOSE

Empirical initial antibiotic treatment of UTI must rely on susceptible data from local studies.

MATERIALS AND METHODS

Retrospective analysis of isolated bacteria from children with UTIs was performed at the university hospital during years 2006-2009. The findings were compared with data collected in a similar study carried out in 2002-2003.

RESULTS

A total of 1439 uropathogens were isolated. Escherichia coli (E.coli) was the leading cause, followed by Enterobacter, and other gram negative bacilli. It was observed resistance of E.coli to ceftriaxone, cefexime, amikacin, gentamycin, and nalidixic acid; Enterobacter to cefexime; and the resistance of gram negative bacilli to gentamicin and cefexime increased significantly. The highest effective antibiotic was Imipenem, ciprofloxacin, and amikacin with 96.7%, 95% and 91% sensitivity rates, respectively, followed by ceftriaxone 77.2%, gentamicin 77%, nitrofurantoin 76.4%, nalidixic acid 74.3% and cefexime with 70%.

CONCLUSION

The use of nitrofurantoin or nalidixic acid as initial empirical antibacterial therapy for cystitis seems appropriate. For cases of simple febrile UTI, the use of initial parenteral therapies with amikacin or ceftriaxone followed by an oral third generation cephalosporin also seemed appropriated, and in cases of severely ill patients or complicated UTI, imipenem as monotherapy or, a combination of Ceftriaxone with an aminoglycoside, are recommended.

The impact of therapeutic delay time on acute scintigraphic lesion and ultimate scar formation in children with first febrile UTI

We assessed the role of therapeutic delay time (TDT) in acute renal cortical scintigraphic lesion (ASL) and ultimate scar formation (USF) in children with first febrile UTI and whether it is affected by the presence of vesico-ureteral reflux (VUR). 230 children, 90 girls and 140 boys with first febrile UTI were included. Radiologic (USG, DMSA, and VCUG), clinical (age, gender, peak fever, therapeutic delay time) and laboratory (CBC with differential count, ANC (absolute neutrophil count), BUN, Creatinine, urine analysis, gram stain, culture, CRP and ESR) variables were analysed. DMSA was performed within 5 days and after six months. VCUG was performed after acute phase of UTI. The differences in TDT according to the presence of ASL, USF and VUR were assessed. And the correlation between ASL or USF with the duration of TDT was assessed. Of 230 patients enrolled, 142 patients had refluxing UTI and 88 patients had non-refluxing UTI. TDT was the risk factor associated with ASL and USF along with presence of VUR. TDT was longer in ASL positive group compared with the ASL negative group. Also USF group showed longer TDT compared with those without USF in both refluxing UTI and non refluxing UTI. The TDT was significantly shorter in USF group with the presence of VUR. Positive linear association was noted between prevalence of ASL and USF and duration of TDT. In conclusion, the impact of UTI on formation of USF may be enhanced by the presence of VUR with shorter duration of TDT.

Antimicrobial therapy of urinary tract infections in children

The main objectives in childhood urinary tract infections are rapid recovery from complaints, prevention of urosepsis and infection-related complications as well as the prevention of renal parenchymal damage. Calculated antibiotic therapy should take the local resistance rates of uropathogens into consideration. The current situation of bacterial resistances differs from region to region. In Escherichia coli, resistance rates against cephalosporins, aminoglycosides, nitrofurantoin und chinolones have been relatively low. In contrast, resistance rates against ampicillin have increased over the last 20 years. A similar trend has been observed for TMP/SMX. The choice of appropriate antibiotics, the duration of therapy and the form of application depend on age, severity of clinical symptoms and the presence of complicating factors. In early infancy, a combination of aminoglycoside/ampicillin or ceftazidime/ampicillin is commonly recommended as first-line treatment in pyelonephritis. Pyelonephritis in young infants should always be treated in a paediatric clinic. In later infancy and childhood, an oral third-generation cephalosporin can be used.

Nephromegaly is a significant risk factor for renal scarring in children with first febrile urinary tract infections

PURPOSE

We determined whether nephromegaly on ultrasound can be used to identify patients with urinary tract infection at increased risk for renal scarring, and we investigated the effect of vesicoureteral reflux on renal scarring.

MATERIALS AND METHODS

We enrolled hospitalized patients with a first febrile urinary tract infection. All patients underwent renal ultrasound and most patients underwent voiding cystourethrography. Renal scarring was assessed using (99m)technetium dimercapto-succinic acid renal scintigraphy at least 6 months after treatment. Children with recurrent urinary tract infections before scintigraphy were excluded from the study.

RESULTS

A total of 545 children (80 with and 465 without nephromegaly) were enrolled. Infection was more severe in patients with than without nephromegaly. The incidence of renal scarring was significantly higher in patients with nephromegaly (90% vs 32%, p <0.001), in kidneys with nephromegaly (80.5% vs 18.7%, p <0.001) and in kidneys with vesicoureteral reflux (41.5% vs 22.2%, p <0.001). Kidneys with nephromegaly had a greater incidence of reflux. The finding of nephromegaly is associated with a greatly increased likelihood of renal scarring in patients with vesicoureteral reflux.

CONCLUSIONS

Our results indicate that ultrasound diagnosis of nephromegaly at onset is associated with a high incidence of renal scarring, and identification of nephromegaly at onset and vesicoureteral reflux are significant risk factors for renal scarring in children with a first febrile urinary tract infection. Nephromegaly is associated with an increased frequency of vesicoureteral reflux and increased likelihood of renal scarring in patients with reflux.

Acute lobar nephronia is associated with a high incidence of renal scarring in childhood urinary tract infections

BACKGROUND

Acute lobar nephronia (ALN) is a severe nonliquefactive inflammatory renal bacterial infection, and requires a longer duration of treatment. The aim of this prospective study was to investigate renal scarring after ALN and to examine the risk factors for renal scarring in children with ALN compared with those with acute pyelonephritis (APN).

METHODS

Patients with computed tomography-diagnosed ALN were enrolled and randomly allocated, with serial entry, to either a 2- or 3-week antibiotic treatment regimen. Age- and gender-matched APN patients served as comparators. Patients underwent dimercaptosuccinic acid scintigraphy at least 6 months later to assess renal scarring.

RESULTS

A total of 218 children (109 ALN, 109 APN) were enrolled. The incidence of renal scarring was similar between 2- and 3-week treatment groups and was higher in ALN patients than in APN patients (89.0% vs. 34.9%, P < 0.001). Renal scarring was prone to occur in children with higher inflammatory indices and longer duration of fever before and after treatment. Multiple regression analysis on independent variables showed that only ALN was significantly associated with a higher incidence of renal scarring.

CONCLUSIONS

Our results showed a new finding that ALN is associated with a very high incidence of renal scarring, in comparison to APN, irrespective of the duration of antibiotic treatment.

The "top-down" approach to the evaluation of children with febrile urinary tract infection

The evaluation of children presenting with urinary tract infection (UTI) has long entailed sonography and cystography to identify all urological abnormalities that might contribute to morbidity. The identification of vesicoureteral reflux (VUR) has been of primary concern since retrospective studies from the 1930s to 1960s established a strong association between VUR, recurrent UTI, and renal cortical scarring. It has been proposed that all VUR carries a risk for renal scarring and, therefore, all VUR should be identified and treated. We will not discuss the controversies surrounding VUR treatment in this review focusing instead on a new paradigm for the evaluation of the child with UTI that is predicated on identifying those at risk for scarring who are most deserving of further evaluation by cystography.

Vesicoureteral reflux, a benign condition

The combination of urinary tract infection (UTI) and vesicoureteral reflux (VUR) is commonly thought to predispose the child to pyelonephritis, renal scarring and, later in life, to hypertension or end-stage renal disease (ESRD). This paradigm has led to the active search, follow-up and treatment of VUR, and also prevention of recurrent UTI in children. The causality of VUR and ESRD is controversial, however. According to recent meta-analyses it is uncertain whether we can prevent renal scarring or ESRD by treating VUR. Studies on VUR are abundant, but the findings and conclusions are confounding. Because of the lack of evidence of the role of VUR, reasonable doubt has recently been presented on the rationale of imaging all children with UTI and treating the children with VUR. The overall importance of VUR is confounded because of the natural tendency of VUR to resolve spontaneously, its dynamic nature, and its different grades in children. The historical studies showing that VUR is much more common, even among healthy children, than usually claimed, have been forgotten. Since it seems that we are referring too many healthy children to unpleasant and possibly unnecessary imaging tests for VUR, we are uncertain when and what kind of VUR-if any-we should treat, and whether our present rationale of addressing VUR truly makes any difference to renal scarring or ESRD in children, we should critically revisit the subject of VUR.

Does early treatment of urinary tract infection prevent renal damage?

OBJECTIVE

Therapeutic delay has been suggested as the most important factor that is likely to have an effect on the development of scarring after acute pyelonephritis. However, this opinion has not been supported by prospective studies, so we tested it.

METHODS

In a prospective clinical study, we evaluated whether the time interval between the onset of the renal infection and the start of therapy correlates with the development of acute inflammatory changes and the subsequent development of renal scars, documented by dimercaptosuccinic acid scintigraphy. A total of 278 infants (153 male and 125 female) aged 0.5 to 12.0 months with their first urinary tract infection were enrolled in the study.

RESULTS

The median time between the onset of infection and the institution of therapy was 2 days (range: 1-8 days). Renal inflammatory changes were documented in 57% of the infants. Renal defects were recorded in 41% of the patients treated within the first 24 hours since the onset of fever versus 75% of those treated on day 4 and onward. Renal scarring was developed in 51% of the infants with an abnormal scan in the acute phase of infection. The frequency of scarring in infants treated early and in those whose treatment was delayed did not differ, suggesting that once acute pyelonephritis has occurred, ultimate renal scarring is independent of the timing of therapy. Acute inflammatory changes and subsequent scarring were more frequent in the presence of vesicoureteral reflux, especially that which is high grade. However, the difference was not significant, which suggests that renal damage may be independent of the presence of reflux.

CONCLUSIONS

Early and appropriate treatment of urinary tract infection, especially during the first 24 hours after the onset of symptoms, diminishes the likelihood of renal involvement during the acute phase of the infection but does not prevent scar formation.

Association between ICAM-1 Gly-Arg polymorphism and renal parenchymal scarring following childhood urinary tract infection

Renal parenchymal scarring (RPS) following urinary tract infection (UTI) is an important cause of renal morbidity in children. Studies have shown that the intensity of the inflammatory response following infection is related to the risk of RPS. However, genetic variability in this response has not been studied. Adhesion molecules play a crucial role in leucocyte recruitment following infection, and polymorphisms have been reported in the genes for key cell adhesion molecules. We have investigated the possibility that children who develop RPS following UTI may exhibit altered genotype or allele frequencies for polymorphisms of the intercellular adhesion molecule-1 (ICAM-1) (exons 4 and 6), E-selectin (exons 2 and 4), platelet endothelial cell adhesion molecule-1 (PECAM-1) (exon 3) and CD11b (3'UTR) genes, which may predict outcome of UTI. DNA was isolated from 99 children shown to have developed RPS, 43 children with no evidence of scarring (NS) following UTI and 170 healthy controls. Genotyping was performed by restriction fragment length polymorphism (RFLP) analysis. When the RPS group was compared with the NS group, there was a significant reduction in the frequency of the ICAM-1 exon 4 A allele (10.6 vs. 21.3%, respectively, chi2 = 6.01, P = 0.014). There was no significant difference in either allele or genotype frequency for any of the other polymorphisms studied. These data suggest that the A allele of the ICAM-1 exon 4 polymorphism may protect against the risk of RPS following UTI and may participate in the regulation of the inflammatory response following UTI.

Clinical significance of primary vesicoureteral reflux and urinary antibiotic prophylaxis after acute pyelonephritis: a multicenter, randomized, controlled study

OBJECTIVES

To evaluate the role of primary vesicoureteral reflux (VUR) in increasing the frequency and severity of urinary tract infections (UTIs) and renal parenchymal damage among patients with acute pyelonephritis and to determine whether urinary antibiotic prophylaxis reduces the frequency and/or severity of UTIs and/or prevents renal parenchymal damage among patients with mild/moderate VUR.

METHODS

Patients 3 months to 18 years of age with acute pyelonephritis, with or without VUR, were assigned randomly to receive urinary antibiotic prophylaxis or not. Patients were monitored every 3 months for 1 year. Dimercaptosuccinic acid renal scans were repeated at 6 months or if there was a recurrence of febrile UTI. Urinalysis and urine culture were performed at each clinic visit. Renal ultrasound scans and voiding cystourethrograms were repeated at the end of 1 year of follow-up monitoring.

RESULTS

Of the 236 patients enrolled in the study, 218 completed the 1-year follow-up monitoring. Groups were similar with respect to age, gender, and reflux grade distribution for those with VUR. No statistically significant differences were found among the groups with respect to rate of recurrent UTI, type of recurrence, rate of subsequent pyelonephritis, and development of renal parenchymal scars.

CONCLUSIONS

After 1 year of follow-up monitoring, mild/moderate VUR does not increase the incidence of UTI, pyelonephritis, or renal scarring after acute pyelonephritis. Moreover, a role for urinary antibiotic prophylaxis in preventing the recurrence of infection and the development of renal scars is not supported by this study.

Multi-institutional experience with PIC cystography—incidence of occult vesicoureteral reflux in children with febrile urinary tract infections

OBJECTIVES

It has been reported that all children with febrile urinary tract infections (FUTIs) and normal voiding cystourethrogram (VCUG) findings show occult reflux (vesicoureteral reflux [VUR]) when examined by cystography performed with positioning of the instillation of contrast at the ureteral orifice (PIC cystography). In this study, we evaluated the reproducibility of this finding using a prospective multi-institutional collaborative examination to determine whether PIC-VUR is as common in such cases as previously shown.

METHODS

From March 2002 to October 2003, four institutions performed PIC cystography consecutively and prospectively in pediatric cases of FUTI (greater than 101 degrees F) who had not shown VUR by conventional VCUG. We correlated the ureteral orifice (UO) configuration and position with the status of PIC-VUR.

RESULTS

PIC cystography was performed in 39 children (31 girls and 8 boys; 75 FUTIs). We identified PIC-VUR in 32 (82%) of 39 children, involving 58 (74%) of 78 ureters. The likelihood of demonstrating PIC-VUR was increased 37-fold if the UO showed a patulous configuration and was increased 9-fold if the UO showed a lateral configuration. PIC-VUR was noted uniformly in UOs showing hydrodistension.

CONCLUSIONS

This multi-institutional registry showed that the incidence of PIC-VUR (82%) in children with FUTI and normal standard VCUG findings is similar to that previously reported. We consider that PIC-VUR likely accounts for the FUTIs.

May we go on with antibacterial prophylaxis for urinary tract infections?

Recurrent urinary tract infections (UTIs), with or without vesicoureteric reflux (VUR), are by far the most frequent reason for long-term antibacterial prophylaxis in infants and children today. However, the strategies of antibacterial prophylaxis for the prevention of recurrent urinary tract infection are no longer universally accepted. In infants and children at risk, the benefits of antibacterial prophylaxis definitively are not yet proven by evident data. To put antibacterial prophylaxis in its place, risk groups for recurrent symptomatic infections, ascending UTI and permanent renal damage have to be defined and the efficacy of prophylaxis in these groups has to be proved by prospective randomised studies. Nevertheless, until the results of these studies are available, antibacterial prophylaxis will remain one of the most frequently practised methods to protect risk patients from pyelonephritic damage and UTI recurrences.

Evaluation of acute pyelonephritis with DMSA scans in children presenting after the age of 5 years

It is generally believed that infants are more susceptible to development of renal scarring after pyelonephritis than children over 5 years old. This view has led to differences in investigations and treatment according to age. The aim of this prospective study was to assess the occurrence of renal parenchymal lesion in children over 5 years admitted with a first-time symptomatic urinary tract infection (UTI). Between October 2000 and April 2002, 52 children aged over 5 years who were admitted to our department with probable acute pyelonephritis (APN) and a positive urine culture were included in this study. All children received antibiotics for 14 days. During the acute phase of infection, scintigraphy with technetium-99m-labeled dimercaptosuccinic acid (DMSA) and ultrasonography (US) were done. Voiding cystourethrography (VCUG) was performed in all children early in the course of the illness, generally within 5-7 days of hospitalization. When scintigraphy showed renal parenchymal changes, repeat scintigraphy was done after at least 3 months to assess the progression of renal abnormalities. Of the 52 children with a first-time documented pyelonephritis, cortical scintigraphy showed renal lesion in 41 children (78.8%). US was normal in all children with normal renal scintigraphy, while it detected renal abnormalities in 16 of the 41 (39 %) with abnormal scintigraphy (p <0.0001). Topographic analysis of the 165 focal lesions showed that 42.4% were localized to the upper poles, 17.5% to the middle third, and 40% to the lower poles of the kidneys. Repeat scintigraphy showed persistent lesions corresponding to those on the initial scan in nine (28.2%) of the 32 children. Renal lesions had partly regressed in 23 (71.8%) of the patients who underwent repeat scintigraphy. Vesicoureteral reflux was observed in 13.4% of kidneys and renal parenchymal abnormalities were identified in 71.4% and 72.2% of renal units, respectively, with and without reflux ( p >0.05). In conclusion, our data did not confirm the conventional opinion that the risk of renal scarring after pyelonephritis is low in children over the age of 5 years. Our findings suggest that renal scintigraphy may be a more appropriate method of investigation than VCUG for evaluation of the children over 5 years with acute pyelonephritis. Additionally, the frequency of scintigraphic changes is high, and a strategy based exclusively on ultrasound findings would miss about 61% of the abnormal renal units. We recommend that all children, irrespective of age, will benefit from further investigations that might prevent or limit the development of scarring process and renal complications.

Acute pyelonephritis and renal scarring in Kuwaiti children: a follow-up study using 99mTc DMSA renal scintigraphy

The aim of this study was to determine the prevalence of renal scarring in a group of Kuwaiti Arab children with their first documented acute pyelonephritis (APN). Eighty-two Kuwaiti Arab children (10 males and 72 females) who had abnormal (99m)Tc DMSA renal scan findings of acute pyelonephritis were prospectively studied with the same imaging modality 6 months after treatment to identify those who developed renal scarring. A micturition cystourethrogram (MCUG) was performed for all of the children 1 month after diagnosis. Children were divided into 3 age groups (<2 years, 2-5 years and above 5 years). The follow-up DMSA renal scans 6 months after diagnosis revealed normalization of renal changes in 56% (46 patients), much improvement with residual renal abnormality in 6% (5 patients), and persistent parenchymal defects in 38% (31 patients). Vesicoureteric reflux (VUR) was found in 32% of children (26/82) and the majority were between grade I and III. Thirteen of those with VUR (50%) developed renal scars on follow-up. Fifty-three percent of the scarred kidneys (19/36) were drained by non-refluxing ureters. In this study, children older than 2 years had less VUR yet were more susceptible to APN and to the development of renal scars. Girls were more prone to developing APN and renal scarring than boys. This work shows that APN is a serious cause for renal scarring in our patients, particularly if associated with other risk factors such as recurrent infections and the female sex.

Diagnosis and management of pediatric urinary tract infections

Urinary tract infection (UTI) is among the most commonly diagnosed bacterial infections of childhood. Although frequently encountered and well researched, diagnosis and management of UTI continue to be a controversial issue with many challenges for the clinician. Prevalence studies have shown that UTI may often be missed on history and physical examination, and the decision to screen for UTI must balance the risk for missed infections with the cost and inconvenience of testing. Interpretation of rapid diagnostic tests and culture is complicated by issues of contamination, false test results, and asymptomatic colonization of the urinary tract with nonpathogenic bacteria. The appropriate treatment of UTI has been controversial and has become more complex with the emergence of resistance to commonly used antibiotics. Finally, the anatomic evaluation and long-term management of a child after a UTI have been based on limited evidence, and newer studies question some of the tenets of prior recommendations. The goal of this review is to provide an up-to-date summary of the literature with particular attention to practical questions about diagnosis and management for the clinician.

Is ACE gene polymorphism a risk factor for renal scarring with low-grade reflux?

The possible relationship between the angiotensin-converting enzyme (ACE) gene insertion/deletion ( I/D) polymorphism and renal scarring secondary to vesicoureteral reflux (VUR) has recently attracted attention and the DD genotype was postulated to be a risk factor for renal scarring. However, available data represent conflicting results. The aim of this study was to investigate the ACE gene I/D polymorphism and the other known risk factors for renal scarring in children with low- and high-grade VUR. The study included 96 (67 females, 29 males) patients (mean age at diagnosis 3.7+/-3.3 years) with VUR that were assessed for ACE I/D gene polymorphism. ACE genotypes were determined as II, ID, and DD using the polymerase chain reaction. The control group consisted of 103 healthy children with the same ethnicity to find the distribution of ACE gene I/D polymorphism in the population. The frequency of renal scarring was 80.8% in the high-grade reflux group and 34.3% in the low-grade reflux group. There was no difference between groups with renal scarring and without scarring with respect to gender, family history of VUR, age at diagnosis of VUR, associated urological abnormalities, frequency of urinary tract infection episodes, and the occurrence of bilateral or unilateral VUR. Genotype DD was found to be a significant risk factor for renal scarring in the study group by multivariate regression analysis (odds ratio 3.79, P=0.011). It was not a risk factor in high-grade reflux patients (odds ratio 0.60, P=0.62). However, it was a risk factor in low-grade patients with respect to renal scarring (odds ratio 4.0, P=0.024). Although renal scarring is not common in low-grade reflux patients, there may be scarring in some patients. DD polymorphism of the ACE gene is a significant risk factor in low-grade reflux patients with renal scarring.

Severe vesicoureteral reflux and chronic renal failure: a condition peculiar to male gender? Data from the ItalKid Project

Primary vesicoureteral reflux (VUR), one of the principal causes of chronic renal failure (CRF), occurs as a result of two distinct and sex-related mechanisms: congenital renal hypoplasia, which is prevalent in males, and acquired renal scarring in females. We used data from the ItalKid Project, a prospective population-based CRF registry of patients undergoing conservative treatment, to evaluate the gender distribution and severity of primary VUR, the age at diagnosis, and the diagnostic and therapeutic methods adopted in children with CRF. The prevalence of males (77.5%), the severity of VUR (grade IV-V), and the early age at diagnosis (18% prenatally) seem to suggest that congenital renal damage is the major cause of pediatric CRF.

Antimicrobial resistance in Escherichia coli in urine samples from children and adults: a 12 year analysis

AIM

To investigate the distribution and antimicrobial resistance in urinary tract pathogens, primarily Escherichia coli, in two age groups, children < or = 2 y and adults 18-50 y, over a period of 12 y.

METHODS

From the database of the microbiological laboratory all urinary tract culture data were extracted and structured according to date, patient age, bacteriological findings, antimicrobial susceptibility results and sample type. Statistical longitudinal analysis of bacteriological findings and antimicrobial resistance trends in the two age groups were performed.

RESULTS

Statistical significance was obtained for the following results. Escherichia coli was the most common pathogen in both age groups and irrespective of sample type. In E. coli resistance to ampicillin and trimethoprim was higher in children than in adults and increased over time in both age groups. Resistance to fluoroquinolones was higher in adults than in children and increased over time in both groups. Resistance to pivmecillinam, cefadroxil and nitrofurantoin was below 2% in 2001 in both age groups.

CONCLUSION

The steadily increasing and now high E. coli resistance levels in children to ampicillin and trimethoprim render empirical therapy with these drugs doubtful. The stable and low levels of resistance to pivmecillinam, cefadroxil and nitrofurantoin (< 2% in 2001) make these drugs reasonable alternatives in uncomplicated lower urinary tract infections.

Incidence of New Renal Parenchymal Inflammatory Changes Following Breakthrough Urinary Tract Infection in Patients With Vesicoureteral Reflux Treated With Antibiotic Prophylaxis: Evaluation by 99M Technetium Dimercapto-Succinic Acid Renal Scan

PURPOSE

Breakthrough urinary tract infections (UTI) are considered an indication for surgical intervention in children with vesicoureteral reflux (VUR) with the goal of preventing new or progressive renal scarring. We assessed the incidence of new renal parenchymal inflammatory changes following breakthrough UTI in patients on antibiotic prophylaxis for VUR.

MATERIALS AND METHODS

We prospectively analyzed 38 patients (62 refluxing renal units) with VUR. All patients experienced a culture documented breakthrough UTI (greater than 100,000 cfu/ml) while taking antibiotic prophylaxis. Dimercapto-succinic acid (DMSA) scans were obtained 4 to 6 weeks after UTI to detect new renal inflammatory changes and all scans were reviewed by the same pediatric nuclear medicine specialist (MM). To avoid misinterpretation of preexistent renal scarring for acute inflammation, new pyelonephritis was confirmed by comparison to prior DMSA scan.

RESULTS

Of 38 patients 14 (38%) had preexistent renal scarring but only 1 (7%) manifested new changes on DMSA scan. Of the remaining 24 patients with normal baseline studies 3 (12.5%) had changes after UTI. Overall, only 4 patients (10.5%) manifested new changes on DMSA scan. Three additional patients who did not have a baseline scan for comparison demonstrated unequivocal changes of acute pyelonephritis on DMSA scan, increasing the incidence to 17% (7 of 41). Of the patients 7 (17%) underwent surgical correction of reflux and 34 (83%) were maintained on antibiotic prophylaxis.

CONCLUSIONS

Of patients with VUR who experienced a single breakthrough UTI while on antibiotic prophylaxis, at most only 17% had renal inflammatory changes on acute DMSA scan. Our findings endorse the usefulness of DMSA scan in tailoring management of VUR and breakthrough UTI cases, and lend support to continued nonoperative management for the majority.

Randomised controlled trial of three day versus 10 day intravenous antibiotics in acute pyelonephritis: effect on renal scarring

BACKGROUND

Acute pyelonephritis often leaves children with permanent renal scarring.

AIMS

To compare the prevalence of scarring following initial treatment with antibiotics administered intravenously for 10 or three days.

METHODS

In a prospective two centre trial, 220 patients aged 3 months to 16 years with positive urine culture and acute renal lesions on initial DMSA scintigraphy, were randomly assigned to receive intravenous ceftriaxone (50 mg/kg once daily) for 10 or three days, followed by oral cefixime (4 mg/kg twice daily) to complete a 15 day course. After three months, scintigraphy was repeated in order to diagnose renal scars.

RESULTS

Renal scarring developed in 33% of the 110 children in the 10 day intravenous group and 36% of the 110 children in the three day group. Children older than 1 year had more renal scarring than infants (42% (54/129) and 24% (22/91), respectively). After adjustment for age, sex, duration of fever before treatment, degree of inflammation, presence of vesicoureteric reflux, and the patients' recruitment centres, there was no significant difference between the two treatments on renal scarring. During follow up, 15 children had recurrence of urinary infection with no significant difference between the two treatment groups.

CONCLUSION

In children with acute pyelonephritis, initial intravenous treatment for 10 days, compared with three days, does not significantly reduce the development of renal scarring.

Hospital-acquired urinary tract infections

Hospital-acquired urinary tract infections have a great impact on clinical medicine. They are almost exclusively complicated urinary tract infections. Clinical diagnosis in some patients. (e.g., sedated patients, paediatric or geriatric patients) might be delayed for the lack of symptoms. About 80% of urinary tract infections are catheter-associated. However, certain diseases favour urinary tract infections: diabetes mellitus or cystic renal diseases, amongst others. Each specialist field (e.g., geriatrics, gynaecology, paediatrics) encounters its own problems concerning diagnosis and treatment of urinary tract infections. Hospital-acquired urinary tract infections can merge into severe infections such as urosepsis and septic shock. The microbiological spectrum encompasses multi-resistant bacteria, thus microbiological sampling prior to therapy is mandatory. Additionally the complicating factors must be diagnosed and treated adequately. The best prophylaxis is to minimize the duration of the urinary catheter and to employ general hygienic procedures.

Paediatric urinary tract infection and the necessity of complete urological imaging

OBJECTIVE

To evaluate voiding cysto-urethrography (VCUG) in assessing children with urinary tract infection (UTI) when renal/bladder ultrasonography and renal scintigraphy show no abnormality.

PATIENTS AND METHODS

A total of 468 renal scintigrams taken in children for an indication of UTI between January 1996 and December 1998 were reviewed. The renal and bladder ultrasonograms of those children with a normal renal scan were then reviewed. Children with both normal renal scans and normal ultrasonography were then evaluated for the frequency and grade of vesico-ureteric reflux (VUR) on VCUG.

RESULTS

Of the 468 patients, 453 (97%) had complete imaging studies; 152 of the children evaluated had normal renal scans, of whom 101 had a normal renal ultrasonogram. Twenty-three (23%) children with both a normal renal scan and renal/bladder ultrasonogram showed VUR on VCUG, of whom 14 had bilateral VUR and 13 grade III or higher VUR.

CONCLUSION

This study indicates that about 23% of patients may have significant VUR despite both a normal renal scan and ultrasonogram. Therefore, VCUG remains important in evaluating and managing children with UTI.

Comparison of hemocytometer leukocyte counts and standard urinalyses for predicting urinary tract infections in febrile infants

OBJECTIVES

To compare the accuracy of standard and hemocytometer white blood cell (WBC) counts and urinalyses for predicting urinary tract infection (UTI) in febrile infants.

METHODS

Enrolled were 230 febrile infants < 12 months of age. All urine specimens were obtained by suprapubic bladder aspiration and microscopically analyzed by the standard urinalysis (UA) and by hemocytometer WBC counts simultaneously, and quantitative urine cultures were performed. Receiver-operating characteristic (ROC) curves were constructed for each method of UA. The optimal cutoff point of the UA test in predicting UTI was determined by ROC analysis.

RESULTS

There were 37 positive urine cultures of at least 1,000 CFU/ml. Of these 37 patients, 9 females and 28 males, 1 had a positive blood culture (Escherichia coli). Thirty (81%) of the positive urine cultures had a bacterial colony count > or = 100,000 colony-forming units/ml, whereas the remaining had between 1,000 and 50,000 colony-forming units/ml. The area under the ROC curve for standard UA was 0.790 +/- 0.053, compared with 0.900 +/- 0.039 for hemocytometer WBC counts (P < 0.05). For hemocytometer WBC counts, the presence of < or =10 WBC/microl appeared to be the most useful cutoff point, yielding a high sensitivity (83.8%) and specificity (89.6%). Standard UA, with a cutoff point of 5 WBC/high power field, had a lower sensitivity (64.9%) and similar specificity (88.1%). The hemocytometer WBC counts showed significantly greater sensitivity and positive predictive value (83.8 and 60.8%, respectively) than the standard urinalysis (64.9 and 51.1%, respectively) (P < 0.05). The accuracy, specificity and likelihood ratio of hemocytometer WBC counts were also greater than that of standard UA (88.7, 89.6 and 8.08% vs. 84.3, 88.1 and 5.44%).

CONCLUSION

Hemocytometer WBC counts provide more valid and precise prediction of UTI in febrile infants than standard UA. The presence of > or =10 WBC/microl in suprapubic aspiration specimens is the optimum cutoff value for identifying febrile infants for whom urine culture is warranted.

Management of pyelonephritis and upper urinary tract infections

The most frequent cause of upper urinary tract infection remains E. coli. Other organisms are found in complicated infections associated with diabetes mellitus, instrumentation, stone, and immunosuppression. The pathogenesis of acute pyelonephritis is reviewed herein, with an emphasis on the virulence factors responsible for its initiation, including urothelial adhesion by P-fimbriae of E. coli and other common factors including hemolysin and aerobactin. Renal damage does not always ensue following such infection. It is seen when toxic oxygen radicals are released during the ischemic episode and the respiratory burst of phagocytosis is marked and prolonged. These events occur when effective antibacterial treatment is delayed when the diagnosis is not made early or when socioeconomic factors prevent treatment. The scarring of chronic pyelonephritis leads to the loss of renal tissue and function and may progress to end-stage renal disease. With effective antibacterial therapy, the immune response by both T and B lymphocytes leads to antibodies that assist in bacterial eradication. Therapy must be both rapid and effective. In many instances, antibacterial agents may be used as outpatient therapy. If the Gram stain shows only gram-negative organisms and if the infection is community acquired, oral outpatient therapy with trimethoprim/sulfamethoxazole or a fluoroquinolone may suffice if the patient has no nausea. When the patient is septic, hospitalization and treatment with parenteral antibiotics are needed. Both ceftriaxone and gentamycin are cost-effective parenteral therapy because only once-daily dosing is needed. If gram-positive organisms are found, an enterococcus should be suspected, and a beta-lactam penicillin such as piperacillin or a third-generation cephalosporin such as ceftriaxone is indicated. If penicillin allergy exists, vancomycin should be used. If the patient does not improve rapidly, diagnostic studies including ultrasound and CT will assist in the diagnosis of obstruction, abscess, or emphysematous pyelonephritis. Most of these complications are now rapidly treated percutaneously, with surgical therapy following as needed. Complicated infections, such as those occurring in patients with anatomic abnormalities, stone, or immunosuppression, are often caused by organisms other than E. coli, and long-term antibacterial therapy often leads to fungal infections such as candidiasis. A recrudescence of tuberculosis is occurring, often with resistance to antituberculous drugs. The increased incidence has been associated with the immunosuppression of AIDS but is also occurring in intravenous drug users, perhaps because of poor nutrition but also owing to noncompliance with treatment. The symptoms of renal tuberculosis are usually limited to fever, frequency, urgency, and dysuria. Hematuria with sterile pyuria is the usual laboratory finding. The young urologist should remember this renal disease in the differential diagnosis of hematuria, because medical therapy can provide a cure.

Antibacterial prophylaxis in children with urinary tract infection

The aim, in conservative management of vesico-ureteric reflux by antimicrobial prophylaxis, is to prevent recurrent febrile urinary tract infections and consequent renal scarring. However, the effects of this prophylactic strategy are difficult to evaluate, since the required studies comparing children on prophylaxis with controls (without prophylaxis but under careful supervision) are lacking. Furthermore, the optimal length of prophylaxis needs to be defined. Since risk of renal scarring is believed to occur more frequently in young people, and since recurrent urinary infections mainly affect girls, the age and sex of subjects are important in the design of a prophylactic regimen. Nitrofurantoin and trimethoprim are the most common agents used for long-term, low-dose antibacterial prophylaxis. Break-through infections still result from non-compliance and from development of bacterial resistance, the latter mainly arising with trimethoprim. Few studies of prophylactic drugs are available that adequately define patient materials and include a random allocation to the different agents. Further studies of the effects of alternative prophylactic agents are called for, preferably combined with fresh insight into the ecological impact on the bowel and periurethral floras.

The long-term consequences of urinary tract infections: a historic and contemporary perspective

The long-term adverse consequences of UTI in childhood are hypertension, impaired renal function, end-stage renal disease, and complications during pregnancy. These adverse effects of UTIs are a result of renal parenchymal damage. Currently, these complications are unusual among patients in industrialized countries, unless kidney damage is present at birth. VUR, the most common abnormality encountered in infants and young children with UTIs, is not a diagnostic entity, but reflects a spectrum of underlying conditions. There may be nonobstructive VUR with no other urinary tract abnormality. VUR may be associated with voiding dysfunction and frequent UTIs. It may be present with bladder outlet obstruction, hydronephrosis, and intrauterine renal damage. Children with intrauterine renal damage are those most likely to develop hypertension and those at greatest risk for progression to end-stage renal disease. Acquired renal injury as a cause of adverse long-term consequences due to UTI is much less common than it was early in this century, probably as a result of improved health care.

Evaluation and management of pediatric urinary tract infections

Urinary tract infections (UTIs) are relatively common in children. We describe the evaluation and management of children with UTIs, as well as the risks and consequences related to the UTI. This article describes a rational approach to the evaluation and management of childhood UTIs with the relation to the natural history and risk factors.

Vesico-ureteric reflux and other risk factors for renal damage: identification of high- and low-risk children

This article reviews the literature with respect to various risk factors for permanent renal damage in children with urinary tract infection. Vesico-ureteric reflux is an important risk factor, but renal damage can occur in the absence of reflux. Renal damage does not always occur in the presence of gross reflux. Renal scars always develop at the same site as a previous infection in the kidney. Recurrent pyelonephritis and delay in therapy increase the likelihood of renal damage, although it is not known how long a delay is dangerous to the human kidney. Recent studies using 99mtechnetium-dimercaptosuccinic acid (DMSA) scintigraphy have not confirmed the findings of previous studies showing that children below 1 y of age are more vulnerable to renal damage. It is more likely that all children run the risk of renal scarring in cases of acute pyelonephritis. The role of bladder pressure is still not entirely understood. Therefore more studies are needed in order to determine the relationship between high voiding pressures in some, otherwise healthy, children with urinary tract infection and renal scarring. The importance of bacterial virulence in the development of renal scarring is unclear. DMSA scintigraphy and voiding cystourethrography are the most reliable tools for identifying children at risk of renal scarring. As a single method DMSA scintigraphy appears to be better than voiding cystourethrography.

Medical or surgical management for children with vesico-ureteric reflux?

A critical survey of the literature on treatment of children with vesico-ureteric reflux was carried out in order to create a basis for the new Swedish management policy. There are few studies that meet modern standards of scientific methodology and provide adequate patient numbers. The only large investigations that randomized patients to operative or non-operative treatment were the Birmingham Reflux Study and the International Reflux Study in Children. In these studies, long-term outcome of renal status and renal function, as well as the number of recurrent infections, were independent of treatment modality. Although pyelonephritic recurrences were less common in the surgically managed group, this did not influence appearance of renal damage. There is no evidence to indicate clear superiority of either medical or surgical management. Further studies are needed to address such questions as the optimal duration of antibacterial prophylaxis and the effect of a dilating reflux that persists into adulthood.

Circumcision policy statement. American Academy of Pediatrics. Task Force on Circumcision

Existing scientific evidence demonstrates potential medical benefits of newborn male circumcision; however, these data are not sufficient to recommend routine neonatal circumcision. In circumstances in which there are potential benefits and risks, yet the procedure is not essential to the child's current well-being, parents should determine what is in the best interest of the child. To make an informed choice, parents of all male infants should be given accurate and unbiased information and be provided the opportunity to discuss this decision. If a decision for circumcision is made, procedural analgesia should be provided.

The DMSA scan in paediatric urinary tract infection

The objective of the present paper was to review the use of the dimercaptosuccinic acid (DMSA) scan in urinary tract infection at British Columbia's Children's Hospital to determine the frequency of cortical defects and the association between vesico-ureteric reflux and the presence of cortical defects in children with urinary tract infection. A total of 129 consecutive children with a urinary tract infection referred for a DMSA scan in a 2-year period (January 1992-January 1994) were retrospectively studied. The results were analysed in terms of kidneys, and the incidence of cortical defects was determined. Eighty-eight patients (68%) had a radiographic micturating cysto-urethrogram within 6 months of the DMSA scan, and in this group the relationship of defects with vesico-ureteric reflux was determined. Overall, 81/258 (31%) of kidneys had a cortical defect on a DMSA scan. Of those who had a micturating cysto-urethrogram, 53/176 (30%) kidneys had vesico-ureteric reflux, and of those that had reflux, 21/53 (40%) had a cortical defect on a DMSA scan. In the group of children without reflux, 38/123 (31%) had a cortical defect. Renal cortical scan defects are common findings in paediatric urinary infection, and frequently occur in the absence of vesico-ureteric reflux. These defects represent either established scars or acute pyelonephritis that can proceed to scarring. The micturating cysto-urethrogram alone is insufficient as a screening modality to identify those kidneys at risk of renal scarring.

Imaging in pediatric urology

A multitude of disorders of the genitourinary tract can occur in children. Although some entities may be diagnosed clinically, radiologic imaging is often necessary for diagnosis and management. The radiologic work-up has been discussed using a problem-oriented approach in five clinical situations: urinary tract infection, hydronephrosis or hydroureter, trauma, swollen scrotum, and hematuria. This discussion provides some general guidelines, although the evaluation of each child may need to be individualized depending on their specific clinical symptomatology.

The natural history of bacteriuria in childhood

Urinary tract infections are common during infancy and childhood but are easily overlooked because of the unspecific symptoms. Prevention of renal scarring and its potential long-term consequences is possible but requires an increased awareness of the diagnosis, the imaging revealing anomalies within the urinary tract, and the long-term supervision. This should include any possibility of the child having pyelonephritic recurrences, which should be treated without delay; however, asymptomatic bacteriuria in infants and children is an innocent condition and screening is not recommended.

Transient pyelonephritic changes on 99mTechnetium-dimercaptosuccinic acid scan for at least five months after infection

A prospective study was performed on 185 children with symptomatic urinary tract infection (UTI), 130F and 55M, having a median age of 0.9 y (range 0.1-9.8) at the time of UTI. The aim of the study was to find out how the 99mTechnetium-dimercaptosuccinic acid (DMSA) scan should be used to investigate UTI, and to follow the development of renal changes during pyelonephritis into subsequent permanent renal damage. All children were investigated with a DMSA scan within 5 days after admission and after 3.9-53.3 (median 9.2) weeks, and 159 were studied again after approximately 2 y (range 1.5-3.9 y). They all underwent micturition cystourethrography at the time of the second study. At the time of infection, the DMSA scan was abnormal in 85% of the children, in 58% at the first follow-up and in 36% at the second follow-up. An abnormal DMSA scan performed within 20 weeks from infection became normal in 38% of cases on the third study, while only 1/10 abnormal DMSA scans performed more than 20 weeks after infection became normal after 1.5-3.9 y. Persistent renal changes were more common in children > 4 y of age than in children < or = 1 y of age. Two months after the presenting infection, it was unusual to see a normal DMSA scan in a child with a VUR gr. > or = 3. The study suggests that DMSA changes after an index UTI may be transient for a longer period of time than has been previously considered. Therefore, in order to detect persistent changes, a DMSA scan should be performed more than 5 months after UTI.

Pyelonephritis provokes growth retardation and apoptosis in infant rat renal cortex

Childhood pyelonephritis is a common cause of renal cortical scarring and hypoplastic kidneys. To understand the mechanisms underlying the cortical lesions, urinary tract infection was induced in three-week-old rats by an intravesical infusion of E. coli, type 06 K13 HL a rat nephropathogenic strain. Four days after infection, histopathological examination showed marked infiltration of leukocytes in the medullary tissue adjoining the calyces and pelvis. In the cortex, signs of inflammation were found only in the cortical zone adjacent to the pelvis. No cells indicative of inflammation were observed in other parts of the cortex. Immunohistochemistry for endogenous proliferating cell nuclear antigen (PCNA) demonstrated a marked decrease in immunoreactivity in proximal tubular (PT) cells. The mitotic response of PT cells, assessed by 3H-thymidine autoradiography, showed a highly significant decrease during the first four days after induction of the infection. Four days after infection, a transient increase in apoptotic cells was observed in cortical cells outside the inflammatory areas. No increase in apoptotic cells was detected in the cortex 10 days after infection. Only a few apoptotic cells were detected in the control kidneys. In conclusion, the data indicate that inhibition of cell proliferation and enhancement of apoptosis may contribute to the renal parenchymal loss after childhood pyelonephritis.

Vesicoureteral reflux in children: incidence and severity in siblings

PURPOSE

We attempted to determine the incidence of vesicoureteral reflux in asymptomatic siblings of children with reflux at different ages and assess the incidence of renal damage in asymptomatic siblings with reflux.

MATERIALS AND METHODS

We reviewed radionuclide cystograms of 482 consecutively referred siblings of children with vesicoureteral reflux, including 295 girls and 187 boys 2 weeks to 12.8 years old (mean age 2.8 years). Ultrasonograms and renal cortical scintigrams of children with reflux were evaluated. All siblings were considered asymptomatic by the referring physicians.

RESULTS

The overall incidence of vesicoureteral reflux was 36.5%, and the incidence in girls and boys was 39.3 and 32.1%, respectively. Children 24 months old or younger had the highest incidence (45.7%) and the highest risk of bilateral reflux. From ages 25 to 72 months the incidence of reflux was 33.1% and in siblings older than 72 months it was 7%. Reflux of urine to the level of the renal pelvis was detected in 28.6% of all referred siblings. Renal damage was observed on sonography or scintigraphy in 4.7% of the siblings with reflux.

CONCLUSIONS

The high incidence of vesicoureteral reflux through age 72 months indicates that it is important to screen siblings of children with reflux at an early age to prevent renal damage, which can occur in the absence of symptomatic urinary tract infection.

Imaging of pyelonephritis

OBJECTIVE

Accurate diagnosis of pyelonephritis using clinical and laboratory parameters is often difficult, especially in children. The main aims of this prospective study were to compare the value of different imaging techniques [renal sonography, cortical scintigraphy with technetium-99m dimercaptosuccinic acid (99mTc DMSA) and computed tomography (CT)] in detecting renal involvement in acute urinary tract infections and to determine the sensitivity of DMSA scans for permanent renal scars 6 months later.

MATERIALS AND METHODS

Between February 1992 and January 1993, 55 children admitted to our pediatric unit with febrile symptomatic urinary tract infections were eligible for analysis. Ultrasonography (US), DMSA scanning and micturating cystourethrography were performed in every case. Only 18 children underwent CT. A second DMSA scan was performed in 48 children a mean of 7.5 months after the first.

RESULTS

US abnormalities were found in 25 children (45 %). The first DMSA scan showed a parenchymal aspect suggestive of pyelonephritis in 51 patients (93 %). Among the 18 patients studied by CT, 14 had abnormalities. Normal US findings did not rule out renal parenchymal involvement. Scintigraphy appeared to be more sensitive than CT for renal involvement. The frequency and degree of initial renal parenchymal damage seemed to correlate with vesicoureteral reflux, but the most severe initial parenchymal defects were not associated with marked clinical or laboratory manifestations. Repeat DMSA scans, performed on 45 kidneys with abnormalities at the first examination, showed resolution in 19, improvement in 16, persistence in 8 and deterioration in 2. The prevalence of vesicoureteral reflux was not higher in patients with renal scarring on the second DMSA scan than in patients whose scans showed an improvement.

CONCLUSION

DMSA scans should be considered as a reference in the detection and follow-up of renal scarring associated with acute urinary tract infection as this technique is more sensitive than US and CT, the latter being unsuitable because it entails radiation exposure and sedation of patients.