The inflammatory response and tissue damage. The example of renal scars following acute renal infection

Improving Management: Novel Guidelines for Diagnosing Urinary Tract Infection in Infants

BACKGROUND

The diagnosis of urinary tract infection (UTI) in the pediatric field remains a topic of debate. In 2011, the American Academy of Pediatrics (AAP) introduced new guidelines for the diagnosis of UTI in patients 2-24 months old. However, concerns were raised regarding these guidelines.

METHODS

This is a retrospective data extraction study that included patients 0-6 months of age who were examined in the pediatric emergency department between 2016 and 2021 and had a urine culture. For each patient, we recorded the diagnosis documented in the medical records, the diagnosis based on the AAP and Israeli guidelines, and the diagnosis according to our 2 proposed protocols. We then compared the percentage of UTI diagnoses according to each diagnostic guideline.

RESULTS

A total of 1432 patients under the age of 6 months underwent urine culture testing during the study period. A total of 83 (5.81%) of these patients were diagnosed with UTI according to the AAP guidelines, 184 of the patients (12.8%) were diagnosed with UTI according to the Israeli guidelines, 102 (7.1%) and 109 (7.6%) of the patients were diagnosed with UTI according to our first and second proposed guidelines, respectively.

CONCLUSIONS

We propose a new diagnostic method (guidelines II) that is suitable for patients older than 2 months, with obligatory criteria of abnormal urine test and a lower threshold for the colony count required for diagnosis compared to the AAP guidelines. Further research is required to examine the sensitivity and specificity of our proposed guidelines, so it may replace the current diverse guidelines.

Clinical Course of Children 1 to 24 Months Old With Positive Urine Cultures Without Pyuria

OBJECTIVE

To describe the clinical course of children with positive urine cultures without pyuria who were not given antibiotics initially, identify predictors of subsequent antibiotic treatment, and evaluate the association between subsequent treatment and urinary tract infection (UTI) within 30 days.

METHODS

We conducted a multicenter retrospective cohort study of children 1 to 24 months old who had positive urine cultures without pyuria and who were not started on antibiotics upon presentation to 3 health care systems from 2010 to 2021. Outcomes included clinical status at the time urine cultures resulted, escalation of care (emergency department visit or hospitalization) and subsequent antibiotic treatment within 7 days, and subsequent UTI within 30 days of presentation.

RESULTS

Of 202 included children, 61% were female and median age was 9 months. Of 151 patients with clinical status information when cultures resulted, 107 (70.8%, 95% confidence interval [CI] 62.9-77.9%) were improved. Two of 202 children (1.0%, 95% CI 0.2-4.0%) experienced care escalation. Antibiotics were started in 142 (82.2%) children, and treatment was associated with prior UTI (risk ratio [RR] 1.20, 95% CI 1.15-1.26) and lack of improvement (RR 1.22, 95% CI 1.13-1.33). Subsequent UTI was diagnosed in 2 of 164 (1.2%, 95% CI 0.1-4.3%) treated and 0 of 36 (0%, 95% CI 0-9.7%) untreated children.

CONCLUSIONS

Seventy percent of children with positive urine cultures without pyuria improved before starting antibiotics; however, >80% were ultimately treated. Future research should study the impact of diagnostic stewardship interventions and various urine testing strategies to optimize the management of children evaluated for UTI.retain-->.

The efficacy and safety of corticosteroids in pediatric kidney scar prevention after urinary tract infection: a systematic review and meta-analysis of randomized clinical trials

BACKGROUND

Acute pyelonephritis (APN) in pediatric patients may lead to kidney scarring and is one of the main causes of permanent kidney damage. The incidence of kidney scarring after one febrile urinary tract infection (UTI) is reported to range from 2.8 to 15%, with the percentage rising to 28.6% after ≥ 3 febrile UTIs. Corticosteroids may have a role in the reduction of kidney scar formation and urine cytokine levels. The possible benefit of adjuvant corticosteroid administration in the reduction of kidney scar formation in children with APN has been recently examined in randomized controlled trials (RCTs).

OBJECTIVES

The aim of this meta-analysis was to provide a summary of the current literature about the efficacy and safety of adjuvant corticosteroid administration in the reduction of kidney scar formation in children with APN.

DATA SOURCES

An extensive literature search through major databases (PubMed/MEDLINE and Scopus) was carried out for RCTs from inception until October 12, 2022, investigating the efficacy and safety of adjuvant corticosteroids in preventing kidney scarring in children with APN. A risk ratio with 95% CI was used for dichotomous outcomes.

RESULTS

In total, 5 RCTs with 918 pediatric patients with APN were included in the study. Adjuvant corticosteroid treatment revealed a statistically significant reduction in kidney scarring (95% CI 0.42-0.95, p = 0.03), without increasing the risk of adverse events like bacteremia, prolonged hospitalization, or recurrence of UTI.

LIMITATIONS

There were limitations regarding sample size (n = 498 children), different classes of corticosteroids (methylprednisolone or dexamethasone), different routes of corticosteroid administration (intravenous or oral), and different day courses (3-day or 4-day course).

CONCLUSIONS

Adjuvant corticosteroid administration seems to have a beneficial effect on kidney scar reduction in children with APN. Future studies should focus on the evaluation of the efficacy and safety of corticosteroids in kidney scarring reduction after APN to strengthen the results of our study. A higher resolution version of the Graphical abstract is available as Supplementary information.

Contemporary Management of Urinary Tract Infection in Children

Urinary tract infection (UTI) is common in children, and girls are at a significantly higher risk, as compared to boys, except in early infancy. Most cases are caused by Escherichia coli Collection of an uncontaminated urine specimen is essential for accurate diagnosis. Oral antibiotic therapy for 7 to 10 days is adequate for uncomplicated cases that respond well to the treatment. A renal ultrasound examination is advised in all young children with first febrile UTI and in older children with recurrent UTI. Most children with first febrile UTI do not need a voiding cystourethrogram; it may be considered after the first UTI in children with abnormal renal and bladder ultrasound examination or a UTI caused by atypical pathogen, complex clinical course, or known renal scarring. Long-term antibiotic prophylaxis is used selectively in high-risk patients. Few patients diagnosed with vesicoureteral reflux after a UTI need surgical correction. The most consequential long-term complication of acute pyelonephritis is renal scarring, which may increase the risk of hypertension or chronic kidney disease later in life. Treatment of acute pyelonephritis with an appropriate antibiotic within 48 hours of fever onset and prevention of recurrent UTI lowers the risk of renal scarring. Pathogens causing UTI are increasingly becoming resistant to commonly used antibiotics, and their indiscriminate use in doubtful cases of UTI must be discouraged.

Diffusion-weighted magnetic resonance imaging is more sensitive than dimercaptosuccinic acid scintigraphy in detecting parenchymal lesions in children with acute pyelonephritis: A prospective study

INTRODUCTION

Static renal scintigraphy is the gold standard for detection of inflammatory changes in the renal parenchyma in acute pyelonephritis. Our aim was to determine whether diffusion-weighted magnetic resonance imaging (DW-MRI) was comparable with static renal scintigraphy (DMSA-SRS) to demonstrate acute renal parenchymal lesions.

OBJECTIVE

To compare ^99mTc-dimercaptosuccinic acid static renal scintigraphy (DMSA-SRS) with diffusion-weighted magnetic resonance imaging (DW-MRI) for detecting acute inflammatory changes in the renal parenchyma in children with febrile urinary tract infection.

METHODS

Thirty-one children (30 girls) aged 3-18 years with a first episode of febrile UTI without a previously detected congenital malformation of the urinary tract, were prospectively included. DMSA-SRS and DW-MRI were performed within 5 days of diagnosis to detect renal inflammatory lesions. The DW-MRI examination was performed without contrast agent and without general anesthesia. Late examinations were performed after 6 months using both methods to detect late lesions.

RESULTS

DW-MRI confirmed acute inflammatory changes of the renal parenchyma in all 31 patients (100%), mostly unilateral. DMSA-SRS detected inflammatory lesions in 22 children (71%; p = 0.002). The lesions were multiple in 26/31 children (84%) on DW-MRI and in 9/22 (40%) on DMSA-SRS. At the control examination, scarring of the renal parenchyma was found equally by DW-MRI and DMSA-SRS in five patients (16%), three of whom were the same patients. The overall concordance of positive and negative late findings occurred in 87% of patients. There was correspondence in the anatomical location of acute and late lesions.

DISCUSSION

The clinical significance of acute and late parenchymal findings on DWI-MR is yet to be determined. A limitation of our study is the age of the patients (older than 3 years) who are less sensitive to scar development; therefore, a smaller number of patients with scars could be analyzed during control examination. Further studies using the DW-MRI should confirm its reliability to detect acute and late lesions in younger children and infants and determine the clinical consequences.

CONCLUSION

DW-MRI has higher sensitivity for detecting acute renal inflammatory lesions and multifocal lesions than DMSA-SRS. The incidence of scars was low and corresponded with the anatomical location of acute and late lesions.

The effect of vitamin A on renal damage following acute pyelonephritis in children: a meta-analysis of randomized controlled trials

BACKGROUND

Renal scarring after acute pyelonephritis (APN) in children is of concern and in the worst cases leads to long-term cardiovascular morbidity. There are reports that vitamin A may alleviate renal damage following APN. We conducted a meta-analysis to investigate the role of vitamin A in the alleviation of renal damage.

METHODS

We searched PubMed, EMBASE, the Cochrane Central Register of Controlled trials (CENTRAL, the Cochrane Library) and the Wang Fang database (Chinese) from their inception to February 3, 2015 for randomized controlled trials (RCTs) investigating vitamin A and renal damage. Primary outcome was number of patients/kidneys with renal damage, defined as persistence of photopenic lesions based on technetium-99m dimercaptosuccinic acid renal scintigraphy. We calculated pooled relative risks for renal damage in the vitamin A group.

RESULTS

Four RCTs, involving a total of 248 patients aged 1-144 months (120 in experimental group, 128 in control group), were included in the meta-analysis. Vitamin A was inversely associated with renal damage (relative risk 0.53, 95 % confidence interval 0.43, 0.67) when compared with placebo group after an average follow-up of 5 months.

CONCLUSIONS

Current evidence indicates that vitamin A may exert a preventive effect on renal damage in children with APN. However, this finding largely relies on a few studies of low methodological quality, i.e., high risk of selection bias, performance bias and attrition bias. Hence, high-quality and adequately powered RCTs are warranted.

Role of Hypoxia Inducible Factor-1α (HIF-1α) in Innate Defense against Uropathogenic Escherichia coli Infection

Uropathogenic E. coli (UPEC) is the primary cause of urinary tract infections (UTI) affecting approximately 150 million people worldwide. Here, we revealed the importance of transcriptional regulator hypoxia-inducible factor-1 α subunit (HIF-1α) in innate defense against UPEC-mediated UTI. The effects of AKB-4924, a HIF-1α stabilizing agent, were studied using human uroepithelial cells (5637) and a murine UTI model. UPEC adherence and invasion were significantly reduced in 5637 cells when HIF-1α protein was allowed to accumulate. Uroepithelial cells treated with AKB-4924 also experienced reduced cell death and exfoliation upon UPEC challenge. In vivo, fewer UPEC were recovered from the urine, bladders and kidneys of mice treated transurethrally with AKB-4924, whereas increased bacteria were recovered from bladders of mice with a HIF-1α deletion. Bladders and kidneys of AKB-4924 treated mice developed less inflammation as evidenced by decreased pro-inflammatory cytokine release and neutrophil activity. AKB-4924 impairs infection in uroepithelial cells and bladders, and could be correlated with enhanced production of nitric oxide and antimicrobial peptides cathelicidin and β-defensin-2. We conclude that HIF-1α transcriptional regulation plays a key role in defense of the urinary tract against UPEC infection, and that pharmacological HIF-1α boosting could be explored further as an adjunctive therapy strategy for serious or recurrent UTI.

Urinary tract infection (UTI), commonly caused by uropathogenic E.coli (UPEC), affects more than 150 million people worldwide, resulting in 14 million hospital visits per year and an estimated total cost of 6 billion dollars in direct health care. Due to the high prevalence of UTI and rapid emergence of antibiotic-resistant bacteria, new effective strategies to prevent and treat UTI are urgently needed. Here, we describe a global regulatory role of transcription factor hypoxia-inducible factor-1 (HIF-1) in innate antimicrobial defense against UPEC. HIF-1 stabilization reduces UPEC attachment to and invasion of uroepithelial cells, and protects bladders from UPEC-mediated cytotoxicity in vivo. In the murine UTI model, we found normal bladder HIF-1 expression is required for efficient UPEC clearance, since HIF-1-deficient mice suffer more severe infection than normal mice. Further studies showed that key elements of host protection provided by HIF-1 regulation are uroepithelial cell nitric oxide and antimicrobial peptide production. This study provides valuable insight into the importance of HIF-1 in supporting host immunity during UTI and its potential as a therapeutic target.

Could pyelonephritic scarring be prevented by anti-inflammatory treatment? An experimental model of acute pyelonephritis

Objectives. This study aimed to demonstrate if the addition of anti-inflammatory treatment to antibiotic therapy shows any superiority to the treatment with antibiotic only. Methods. Forty-nine Wistar rats were divided into 7 groups. Pyelonephritis was performed by E. coli injection to upper pole of kidneys except control group. Group 2 was not treated. Ceftriaxone, ketoprofen, “ceftriaxone + ketoprofen,” methylprednisolone, and “ceftriaxone + methylprednisolone” were given in the groups. The technetium-99m-dimercaptosuccinic acid scintigraphies were performed in 3rd day to detect pyelonephritis and 10th week to detect renal scarring. All kidneys were also histopathologically evaluated. Results. When 3rd day and 10th week scintigraphies were compared, initial 2.00 ± 0.30 point pyelonephritis score resulted in 0.71 ± 0.36 renal scar score in “ceftriaxone + ketoprofen” group (P = 0.039). Initial 2.00 ± 0.43 point pyelonephritis score resulted in 0.86 ± 0.26 renal scar score in “ceftriaxone + methylprednisolone” group (P = 0.041). Renal scar score was declined in “ceftriaxone + ketoprofen” group and “ceftriaxone + methylprednisolone” group compared with no-treatment group on 10th week of the study (P = 0.026, P = 0.044). On histopathological evaluation, it was seen that renal scar prevalence and expansion declined significantly in “ceftriaxone + ketoprofen and ceftriaxone + methylprednisolone” (P = 0.011, P = 0.023). Conclusion. It was evidenced that ceftriaxone treatment in combination with ketoprofen or methylprednisolone declined scar formation in scintigraphic and histopathologic examinations of the kidneys.

Does prompt treatment of urinary tract infection in preschool children prevent renal scarring: mixed retrospective and prospective audits

OBJECTIVE

To test whether active management of urinary tract infections (UTI) in young children by general practitioners can reduce kidney scarring rates.

DESIGN

A comparison of two audits in Newcastle, of children aged <8 years, presenting with UTIs ; a retrospective audit of conventional management during 1992-1995 (1990s) versus a prospective audit of direct access management during 2004-2011 (2000s).

MAIN OUTCOME MEASURES

Kidney scarring rates, and their relationship with time-to-treat.

RESULTS

Children with a first UTI in the 2000s compared to those in the 1990s, were referred younger, were half as likely to have a renal scar (girls OR 0.47, 95% CI 0.29 to 0.76; boys 0.35, 0.16 to 0.81), and were about 12 times more likely to have vesicoureteric reflux without scarring (girls 11.9, 4.3 to 33.5; boys 14.4, 4.3 to 47.6). In the 2000s, general practitioners treated about half the children at first consultation. Children who were treated within 3 days of their symptoms starting were one-third as likely to scar as those whose symptoms lasted longer (0.33, 0.12 to 0.72).

INTERPRETATION

Most kidney defects seen in children after UTIs, are acquired scars, and in Newcastle, active management in primary care has halved this rate.

Effect of Thymoquinone on Oxidative Stress in Escherichia coli-Induced Pyelonephritis in Rats

BACKGROUND

Recurrent urinary tract infections are important in children and adults with diabetes mellitus and/or incontinence due to risk of pyelonephritis (PYN) and renal damage. There is a positive correlation released free radicals during PYN and renal damage. Experimental studies showed that antioxidant agents improve renal damage when used immediately after bacterial inoculation.

OBJECTIVE

The aim of the present study was to evaluate whether treatment by thymoquinone (TQ) before or during Escherichia coli inoculation prevents oxidative damage in acute pyelonephritis (PYN) in an ascending obstructive rat model.

METHODS

In this study, 42 Wistar rats were grouped as follows: control, PYN (24, 48, and 72 hours), and TQ-PYN (24, 48, and 72 hours). E. coli (1 ×10(9) colony forming units) was inoculated into the bladder via urethral catheterization in both the PYN and TQ groups. TQ injections were performed 24 hours before bacteria inoculation and repeated at 24-hour intervals during the indicated time at a dose of 10 mg/kg body weight intraperitoneally in TQ groups.

RESULTS

Superoxide dismutase activity was statistically lower in the TQ-PYN-48 and -72 groups than the PYN-48 and -72 groups (P < 0.001, P = 0.004, respectively). Catalase activity was significantly higher in PYN-24, -48, and -72 groups than the control group (P < 0.001). In addition, there was a significant difference between the TQ-PYN-24, -48, and -72 groups and PYN groups in terms of glutathione peroxidase activity (P < 0.001, P = 0.026, P = 0.046, respectively). When the TQ-PYN-72 group was compared with the PYN-72 group, malondialdehyde levels were significantly lower in the TQ-PYN-72 group than in the PYN-72 group (P = 0.033). A histologic examination also confirmed the protective effect of TQ. In statistical analysis of histopathologic findings, there were significant differences between the PYN-24 and TQ-PYN-24, PYN-48 and TQ-PYN-48, and PYN-72 and TQ-PYN-72 groups (P = 0.008, P < 0.001, P < 0.001, respectively).

CONCLUSIONS

The results indicate that TQ administration attenuated the oxidative damage that occurred in PYN and, therefore, could be used as a supportive agent to protect the kidneys from oxidative damage caused by PYN.

Evaluation of the effects of ozone therapy on Escherichia coli-induced cytitis in rat

OBJECTIVES

The aim of the study was to investigate the effect of ozone on oxidative/nitrosative stress and bladder injury caused by Escherichia coli in rat bladder.

METHODS

Twenty-one Wistar-Albino-type female rats included in the study were divided into three groups of equal number: (1) sham operation (control), (2) E. coli-only (EC), (3) EC + ozone. After ozone therapy for 3 days, urine and tissue samples were obtained for biochemical, microbiological, and histopathological analysis.

RESULTS

Tissue malondialdehyde (MDA), myeloperoxidase (MPO), and nitric oxide (NO) level were increased, whereas superoxide dismutase (SOD) and glutathione peroxidase (GPx) activity was decreased in the EC group. MDA, MPO, and NO levels were decreased, whereas SOD, GPx activity was increased in the ozone-treated group. Also, there was no bacterial translocation in this group.

CONCLUSION

The results of the present study suggest that ozone may be used as an agent to protect the bladder from oxidative/nitrosative stress occurring in cystitis.

[Diagnostics and therapy of urinary tract infections]

In infants and young children, urinary tract infections (UTI) often present with unspecific symptoms. Appropriate techniques of urine sampling play an important role for accurate microbiological diagnosis. In infants urine sampling by bladder puncture or transurethral catheter is recommended. In young infants with suspected pyelonephritis, calculated antibiotic treatment should be initiated parenterally with a combination of a third generation cephalosporin or an aminoglycoside with ampicillin. After the age of 3-6 months group 3 oral cephalosporins can be used in uncomplicated pyelonephritis. With the first febrile UTI early sonography is recommended to provide information about renal parenchymal involvement and to exclude malformations of the kidneys and urinary tract. Strategies for the recognition of vesicoureteral reflux and renal damage are under discussion. Recently published guidelines by the American Academy of Pediatrics for the diagnosis and management of UTI in febrile children and infants aged 2-24 months will most likely influence the still pending German guidelines.

Interleukin-6 and interleukin-8 levels in the urine of children with renal scarring

BACKGROUND

Acute pyelonephritis (APN) is one of the most significant bacterial infections in infancy and early childhood, and can lead to permanent kidney damage and chronic renal failure.

OBJECTIVE

To evaluate interleukin-6 (IL-6) and interleukin-8 (IL-8) levels in the urine of children with renal scarring (RS), searching for clinical information about the immuno-inflammatory process that contributes to RS.

METHODS

Urine concentrations of IL-6 and IL-8 were evaluated in 50 children, 33 with RS detected after an episode of acute pyelonephritis (group A) and 17 children with a history of acute pyelonephritis, but without RS (group B). These children were divided into four groups: group A(1), 23 children with RS and vesicoureteral reflux (VUR); group A(2), 10 children with RS without VUR; group B(1), 13 children without RS and without VUR; group B(2), 4 children without RS, but with VUR. None of them had had urinary tract infection for a minimum of 6 months. To avoid dilution effects, urinary levels of IL-6 and IL-8 were expressed as the ratio of cytokine to urinary creatinine (pg/mg).

RESULTS

Urinary IL-8 levels were below the lower detection limit in all samples. IL-6 was detectable in the majority of children with RS and below the detection limits in the urine samples of children without RS. There were no statistically significant differences between urinary interleukin-6 levels in children with and those without VUR. There was a significant relationship between the grade of renal scars, the time passed since the last episode of acute pyelonephritis and the urinary levels of IL-6 (p < 0.0001 and p < 0.04 respectively).

CONCLUSION

Further experimental studies are required to demonstrate the correlation between histopathology and urinary cytokine levels.

Anti-inflammatory and antioxidant activity of thymoquinone in a rat model of acute bacterial prostatitis

Prostatitis plays a major role in morbidity and mortality related to prostate diseases. The aim of this study was to detect whether thymoquinone (TQ) could ameliorate oxidative damage and the proliferative response induced by Escherichia coli ( E. coli) in rats. A total of 42 adult male Wistar rats were used. The rats were randomly divided into seven groups (three treatment groups, three infected groups and one control group). Control group received saline and was killed 24 h after saline administration. Infected rats were killed after 24, 48 and 72 h following direct injection of E. coli into the prostate. Treatment groups were administered with 10 mg/kg dose of TQ intraperitoneally following E. coli injection and after 24 and 48 h following E. coli injection. The rats were killed at 24, 48 and 72 h after the first drug administration. Each group was compared with each other and with the control group. In addition, infected groups were compared with treatment groups. Our findings show that the treatment with TQ has a protective effect against bacterial prostatitis-induced tissue injury. Increase in malondialdehyde levels and histological damage caused by E. coli were improved markedly with TQ treatment. TQ treatment particularly increased the activity of glutathione peroxidase and decreased the activities of catalase and superoxide dismutase. These observations might be attributed, at least in part, to the antioxidant effect of TQ and suggest that it could be a clinically valuable agent in the prevention of acute prostatitis caused by E. coli.

Adjunctive oral methylprednisolone in pediatric acute pyelonephritis alleviates renal scarring

OBJECTIVE

To determine if glucocorticoids can prevent renal scar formation after acute pyelonephritis in pediatric patients.

METHODS

Patients younger than 16 years diagnosed with their first episode of acute pyelonephritis with a high risk of renal scar formation (ie, inflammatory volume ≥ 4.6 mL on technetium-99m-labeled dimercaptosuccinic acid scan [DMSA] or abnormal renal ultrasonography results) were randomly assigned to receive either antibiotics plus methylprednisolone sodium phosphate (1.6 mg/kg per day for 3 days [MPD group]) or antibiotics plus placebo (placebo group) every 6 hours for 3 days. Patients were reassessed by using DMSA 6 months after treatment. The primary outcome was the development of renal scars.

RESULTS

A total of 84 patients were enrolled: 19 in the MPD group and 65 in the placebo group. Patient characteristics were similar between the 2 groups, including the acute inflammatory parameters and the initial DMSA result. Renal scarring was found in 33.3% of children treated with MPD and in 60.0% of those who received placebo (P < .05). The median cortical defect volumes on follow-up DMSA were 0.0 mL (range: 0-4.5 mL) and 1.5 mL (range: 0-14.8 mL) for the MPD and placebo groups, respectively (P < .01). Patients in the MPD group experienced faster defervescence after treatment than the placebo group.

CONCLUSIONS

Adjunctive oral MPD therapy reduced the occurrence and/or severity of renal scarring after acute pyelonephritis in these hospitalized children who had a high risk of renal scar formation.

Age-related renal parenchymal lesions in children with first febrile urinary tract infections

OBJECTIVE

The aim of this study was to define the association between age and the occurrence of acute pyelonephritis and renal scars.

METHODS

Between 1999 and 2002, all children 0 to 14 years of age consecutively seen with a first febrile urinary tract infection were enrolled in the study. (99m)Tc-Dimercaptosuccinic acid renal scintigraphy was performed within 5 days after admission for the detection of renal parenchymal involvement. The presence of vesicoureteral reflux was assessed by using cystography performed 1 month after the infection. If the acute scan results were abnormal, then follow-up (99m)Tc-dimercaptosuccinic acid scanning was performed after 6 months, to assess the frequency of scars.

RESULTS

A total of 316 children were enrolled in the study (190 children <1 year, 99 children 1-4 years, and 27 children 5-14 years of age). (99m)Tc-Dimercaptosuccinic acid scintigraphy revealed that 59% of the children had renal involvement in the acute phase of infection. The frequency of kidney involvement in infants <1 year of age (49%) was significantly lower than that in children 1 to 4 years of age (73%) and >5 years of age (81%). Of the 187 children with positive acute (99m)Tc-dimercaptosuccinic acid scan results, 123 underwent repeat scintigraphy after 6 months. Renal scars were found for 28% of children <1 year, 37% of children 1 to 4 years, and 53% of children 5 to 14 years of age. No significant differences in the frequency of scars and the presence or absence of vesicoureteral reflux were noted.

CONCLUSIONS

Our findings confirm that acute pyelonephritis and subsequent renal scarring occur only in some children with first febrile urinary tract infections. Children <1 year of age with febrile urinary tract infections have a lower risk of parenchymal localization of infection and renal scarring.

Early treatment of acute pyelonephritis in children fails to reduce renal scarring: data from the Italian Renal Infection Study Trials

OBJECTIVES

The American Academy of Pediatrics recommendation for febrile infants and young children suspected of having a urinary tract infection is early antibiotic treatment, given parenterally if necessary. In support of this recommendation, data suggesting that delay in treatment of acute pyelonephritis increases the risk of kidney damage are cited. Because the risk was not well defined, we investigated renal scarring associated with delayed versus early treatment of acute pyelonephritis in children.

METHODS

The research findings are derived from 2 multicenter, prospective, randomized, controlled studies, Italian Renal Infection Study 1 and 2, whose primary outcomes dealt with initial antibiotic treatment and subsequent prophylaxis, respectively. From the 2 studies, we selected the 287 children with confirmed pyelonephritis on acute technetium-99m-dimercaptosuccinic acid scans who underwent repeat scanning to detect scarring 12 months later. The children were 1 month to <7 years of age when they presented with their first recognized episode of acute pyelonephritis in northeast Italy.

RESULTS

Progressive delay in antibiotic treatment of acute pyelonephritis from <1 to >/=5 days after the onset of fever was not associated with any significant increase in the risk of scarring on technetium-99m-dimercaptosuccinic acid scans obtained 1 year later. The risk of scarring remained relatively constant at 30.7 +/- 7%. Clinical and laboratory indices of inflammation were comparable in all groups, as was the incidence of vesicoureteric reflux.

CONCLUSIONS

Early treatment of acute pyelonephritis in infants and young children had no significant effect on the incidence of subsequent renal scarring. Furthermore, there was no significant difference in the rate of scarring after acute pyelonephritis when infants and young children were compared with older children.

Vitamin E administration at the onset of fever prevents renal scarring in acute pyelonephritis

We evaluated the protective effects of antioxidant at the onset of fever on renal damage in a rat model of acute pyelonephritis. Twenty rats were allocated to four groups. In groups 1 to 3, the animals were given direct inoculation of Escherichia coli into the right kidney, and group four served as control. All rats in groups 1 to 3 were given once-daily intraperitoneal injections of ceftriaxon for five consecutive days, beginning on the third day after inoculation. The animals' body temperatures were monitored; as soon as body temperature reaches 38 degrees C, the rats in group 2 were given allopurinol co-treatment, whereas, in group 3, vitamin E co-treatment was started at fever onset. Both kidneys were excised 6 weeks later, for the evaluation of histopathologic changes, apoptotic damage, and concentrations of transforming growth factor-beta (TGF-beta). Only minimal changes were found in control samples. Pathologic scores of inflammation and fibrosis in group 1 were higher than in the vitamin E and allopurinol groups (P < 0.05). Apoptosis index was also decreased in groups 2 and 3, compared to group 1 (P < 0.05). There was no significant difference in average TGF-beta levels between study groups. These findings suggest that administration of vitamin E or allopurinol following the onset of fever can reduce renal damage in pyelonephritis.

The role of dexamethasone on decreasing urinary cytokines in children with acute pyelonephritis

Cytokines play a major role in renal scar formation following febrile urinary tract infection (UTI). We investigated the role of dexamethasone combined with antibiotics in diminishing urinary interleukin-6 (UIL-6) and UIL-8 concentrations during the acute phase of pyelonephritis compared with standard antibiotic therapy. UIL-6 and UIL-8 concentrations were determined by enzyme immunoassay in 34 children with pyelonephritis who were treated with ceftriaxone plus dexamethasone (case group) and in 20 patients with the same diagnosis treated with ceftriaxone alone (control group). Urine samples were obtained at the time of presentation prior to drug administration and at follow-up 72 h after initiation of medication. Creatinine concentrations were also determined, and cytokine/creatinine ratios were calculated to standardize samples. Differences between cytokine/creatinine ratios in initial and follow-up urine samples were significant in the case group (P < 0.001) but not for controls. In addition, combined antibiotic and dexamethasone significantly decreased UIL-6 and UIL-8 concentrations compared with antibiotic alone (P < 0.05). We conclude that dexamethasone combined with antibiotics significantly decreases UIL-6 and UIL-8 levels in patients with acute pyelonephritis. This suggests that the clinical use of corticosteroids may prevent scar formation following febrile UTI.

Prospective, randomized trial comparing short and long intravenous antibiotic treatment of acute pyelonephritis in children: dimercaptosuccinic acid scintigraphic evaluation at 9 months

OBJECTIVE

We report a prospective, randomized, multicenter trial that compared the effect of 3 vs 8 days of intravenous ceftriaxone treatment on the incidence of renal scarring at 6 to 9 months of follow-up in 383 children with a first episode of acute pyelonephritis.

METHODS

After initial treatment with intravenous netilmicin and ceftriaxone, patients were randomly assigned to either 5 days of oral antibiotics (short intravenous treatment) or 5 days of intravenous ceftriaxone (long intravenous treatment). Inclusion criteria were age 3 months to 16 years and first acute pyelonephritis episode, defined by fever of >38.5 degrees C, C-reactive protein level of >20 mg/L, and bacteriuria at >10(5)/mL. All patients underwent 99m technetium-dimercaptosuccinic acid scintigraphy 6 to 9 months after inclusion. A total of 548 children were included, 48 of whom were secondarily excluded and 117 of whom were lost to follow-up or had incomplete data; therefore, 383 children were eligible, 205 of them in the short intravenous treatment group and 178 in the long intravenous treatment group.

RESULTS

At inclusion, median age was 15 months, median duration of fever was 43 hours, and median C-reactive protein level was 122 mg/L. A total of 37% (143 of 383) of patients had a vesicoureteral reflux grades 1 to 3. Patient characteristics at inclusion were similar in both groups, except for a significantly higher proportion of girls in the short intravenous treatment group. The frequency of renal scars at scintigraphy was similar in both groups. Multivariate analysis demonstrated that renal scars were significantly associated with increased renal height at initial ultrasound and with the presence of grade 3 vesicoureteric reflux.

CONCLUSIONS

The incidence of renal scars was similar in patients who received 3 days compared 8 days of intravenous ceftriaxone. Increased renal height at initial ultrasound examination and grade 3 vesicoureteric reflux were significant risk factors for renal scars.

Relationship Among Vesicoureteral Reflux, Urinary Tract Infection and Renal Damage in Children

PURPOSE

We studied the relationship among vesicoureteral reflux, urinary tract infection and permanent renal damage in children.

MATERIALS AND METHODS

We retrospectively analyzed 303 children younger than 2 years with a first time, nonobstructive, culture verified urinary tract infection. The protocol included ultrasonography and voiding cystourethrography within 3 months after urinary tract infection, and (99m)technetium dimercapto-succinic acid scintigraphy after 1 to 2 years.

RESULTS

Vesicoureteral reflux was found in 36 of 163 boys (22%) and in 44 of 140 girls (31%). Of the 303 patients 80 (26%) had permanent renal damage according to dimercapto-succinic acid scintigraphy. The rate of abnormality increased significantly with grade of vesicoureteral reflux in boys and girls. The relative risk of renal damage was significantly increased in patients with vesicoureteral reflux grade II and higher. Maximum C-reactive protein concentration, maximum temperature during urinary tract infection, presence of vesicoureteral reflux and febrile recurrences of urinary tract infection were significantly related to permanent renal damage. In stepwise logistic regression vesicoureteral reflux was the only independent variable for boys, while C-reactive protein and vesicoureteral reflux were independent factors for girls.

CONCLUSIONS

There was a significant relationship between grade II vesicoureteral reflux and higher and permanent renal damage in boys and girls. However, while the association between renal damage and vesicoureteral reflux was evident in boys, the role of urinary tract infection and renal inflammation seemed to be equally or more important in girls. These findings support the concept that renal damage is associated with vesicoureteral reflux and is often congenital in boys, while in girls it is more related to urinary tract infection with vesicoureteral reflux as a reinforcing factor.

Vesicoureteric reflux and tumor necrosis factor-alpha gene polymorphism

AIM

To determine the role of tumor necrosis factor-alpha (TNF-alpha) gene polymorphism in promoting renal scarring among patients with vesicoureteric reflux (VUR). This genetic variant involves a guanosine to adenine transition at position -308, and this single-base polymorphism is associated with increased transcription of the TNF-alpha gene. Recent studies suggest that the TNF-alpha gene may be associated with predisposition to renal scarring.

PATIENTS AND METHODS

A total of 195 (51.8% females) patients with VUR demonstrated by voiding cystourethrogram were recruited, 126 of them with reflux nephropathy diagnosed by dimercaptosuccinic scan. The control group included 266 healthy individuals. Genotyping was performed by polymerase chain reaction and digestion with a restriction enzyme.

RESULTS

Allele frequencies of -308G and -308A were 83.8% and 16.2%, respectively in patients with VUR and 88.9% and 11.1%, respectively in controls (P<0.05). No differences were found in genotype distribution related to presence/absence of renal scars. There was no relationship between TNF-alpha genotype and grade of VUR or the presence of proteinuria.

CONCLUSIONS

Our data suggest that the TNF-alpha AA genotype is not associated with reflux nephropathy. The TNF-alpha-308A allele could be related to a higher susceptibility to VUR.

Caffeic acid phenethyl ester suppresses oxidative stress in Escherichia coli-induced pyelonephritis in rats

Although oxidative damage is known to be involved in inflammatory-mediated tissue destruction, modulation of oxygen free radical production represents a new approach to the treatment of inflammatory diseases. Caffeic acid phenethyl ester (CAPE), an active component of propolis from honeybee hives, has antioxidant, anti-inflammatory and antibacterial properties. For that reason, we aimed to investigate the efficiency of CAPE administration in preventing oxidative damage in pyelonephritis (PYN) caused by Escherichia coli. In this study, 35 Wistar rats were grouped as follows: control, PYN 24 h, PYN 48 h, PYN 72 h, CAPE 24 h, CAPE 48 h and CAPE 72 h. E. coli (1 x 10(9) c.f.u.) were inoculated into the rats in both PYN and CAPE groups via urethral catheterization. Ten microM/kg-body weight CAPE was injected to the rats in all CAPE groups 24 h before E. coli infection, and injections were repeated at 24-h intervals. Rats were sacrificed 24 h, 48 h and 72 h after infection in both PYN and CAPE groups. Malondialdehyde (MDA) and nitric oxide (NO) levels were significantly increased in kidneys of PYN groups. The activities of the antioxidant enzymes, catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and xanthine oxidase (XO) were also elevated by E. coli. However, CAPE administration reduced MDA and NO levels, as well as XO activity, although it increased SOD and GSH-Px activities. Histopathological examination showed that CAPE reduced the inflammation grade induced by E. coli. In conclusion, CAPE administrations decrease the oxidative damage occurring in PYN and therefore could be used for medical management of bacterial nephropathy.

Effect of a selective cyclooxygenase-2 inhibitor on renal scarring

BACKGROUND

Scarring is one of the steps of excessive wound healing, causing dysfunction of the involved tissues and clinically poor cosmetics. The aim of this study was to examine the effect of a highly selective cyclooxygenase-2 (COX-2) inhibitor on renal scar formation in experimental pyelonephritis.

MATERIALS AND METHODS

Four groups of 10 Balb/C mice were formed. In groups I and II following the inoculation of lipopolysaccharide (LPS) into both kidneys, 0.18 and 0.36 mg/day of rofecoxib was given respectively via intraperitoneal route for 5 days. No medication was applied following physiological saline solution injection to both kidneys of the mice in group III (negative control group). After group IV's LPS inoculation on the first day, saline solution (1 ml/day) was given intraperitoneally for 5 days (positive control group). Following the exposure of both kidneys, LPS of Escherichia coli (5 mg/kg) was injected into the kidneys of groups I, II, and IV. In group III, saline solution (0.1 ml) was used instead of LPS. Three days after the inoculation of LPS, solutions containing 0.18 and 0.36 mg of COX-2 inhibitor were given intraperitoneally for 5 days in groups I and II. No medication was used for the mice in group III. Six weeks after the inoculation of LPS and saline solution, all mice were humanely euthanized. Bilateral nephrectomies were done on each group of mice, and histopathological examination was performed.

RESULTS

Inoculation of LPS into the renal parenchyma caused pyelonephritis and scar formation in all groups. The degree of pyelonephritis and scar formation was lesser in groups in which COX-2 inhibitors were used. The degree of scar formation was lesser in group II, in which 0.36 mg more of COX-2 inhibitor was used than in group I (0.18 mg of COX-2 inhibitor).

CONCLUSION

In our study model, direct inoculation of LPS to kidneys caused experimentally induced pyelonephritis. Renal scar formation was effectively prevented through the utilization of rofecoxib at 0.36-mg doses.

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.

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.

Can MRI replace DMSA in the detection of renal parenchymal defects in children with urinary tract infections?

BACKGROUND

Renal parenchymal defects may be a consequence of urinary tract infections (UTI) in childhood. MRI is a non-radiation imaging modality compared with DMSA scanning.

OBJECTIVE

To compare DMSA with MRI for the detection of renal parenchymal defects in children presenting for radiological investigation after a first UTI.

MATERIALS AND METHODS

Both DMSA and MRI were performed at the same appointment in 37 children (aged 4 months-13 years; mean 4.5 years) with a history of UTI. Both planar and SPECT DMSA were performed. MRI of the kidneys employed axial and coronal T1-, T2- and fat-saturated T1-weighted (T1-W) sequences. Some children had imaging after IV contrast medium.

RESULTS

The coronal fat-saturated T1-W sequence was the best sequence and it detected all the findings on MRI. MRI had a sensitivity of 77% and a specificity of 87% for the detection of a scarred kidney using DMSA as the gold standard. MRI diagnosed pyelonephritis in two children that had been interpreted as scarring on DMSA.

CONCLUSIONS

Renal MRI using a single, coronal, fat-saturated T1-W sequence is a rapid, accurate and minimally invasive technique for the detection of renal scarring that does not employ ionizing radiation.

TUMOR NECROSIS FACTOR-α GENE POLYMORPHISM IN REFLUX NEPHROPATHY

PURPOSE

Interstitial scarring contributes to the progression of renal failure in reflux nephropathy. The proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) has been implicated in the disease susceptibility and pathogenesis of several inflammatory diseases promoting interstitial infiltration of inflammatory cells. We evaluate the frequency of TNF-alpha gene polymorphism in patients with reflux nephropathy.

MATERIAL AND METHODS

Renal scarring was evaluated with technetium dimercapto-succinic acid renal scan. Genotyping was performed on 104 patients with reflux nephropathy and 30 controls for the TNF-alpha gene polymorphisms using polymerase chain reaction and restriction digest. This polymorphism involved a guanidine to adenosine transition at position -308 and was designated as TNF1 (-308G) and TNF2 (-308A).

RESULTS

The allele frequencies of TNF1 and TNF2 were 18.8% and 81.2% in patients with reflux nephropathy and 76.7% and 23.3% in controls, respectively. The genotype distribution of TNF-alpha-AA was significantly higher (66.4% vs 10%, p <0.05), while the TNF-alpha-GG was lower (13.4% vs 60%, p <0.05) in patients with reflux nephropathy compared to controls.

CONCLUSIONS

This study demonstrates for the first time the association of the cytokine TNF-alpha gene polymorphism in patients with reflux nephropathy. Our data suggest that patients with vesicoureteral reflux and TNF-alpha AA genotype may have increased susceptibility to reflux nephropathy.

Evaluation of inflammatory and renal-injury markers in women treated with antibiotics for acute pyelonephritis caused by Escherichia coli

The evolution and the relationship between inflammatory and renal-injury markers in women with acute uncomplicated pyelonephritis under antimicrobial therapy were investigated in a prospective study. Markers were measured before and 6 and 24 h after the intravenous administration of 1 g of ceftriaxone. Before treatment, the median levels of all markers except the serum creatinine levels were high. Twenty-four hours after the onset of antibiotic treatment, the C-reactive protein (CRP) level continued to be high, while the serum interleukin-6 (IL-6) levels and the urine IL-6, IL-8, albumin, and immunoglobulin G (IgG) levels decreased significantly. In contrast, serum creatinine and tumor necrosis factor alpha levels and urine N-acetyl-beta-glucosaminidase, alpha1-microglobulin, and beta2-microglobulin levels did not change over time. There was a significant correlation between IL-6 and IL-8 levels and urine albumin and IgG levels (urine albumin and IgG levels are glomerular and urinary tract-injury markers) as well as between serum CRP levels and the levels of the tubular-injury markers. In women with acute pyelonephritis, appropriate antibiotic treatment rapidly decreases serum IL-6 levels and urine IL-6 and IL-8 levels, which correlate well with urine albumin and IgG levels.

Plasma and urinary soluble adhesion molecule expression is increased during first documented acute pyelonephritis

BACKGROUND

The degree of inflammatory reaction and leucocyte trafficking during acute pyelonephritis has been related to the risk of developing renal parenchymal scarring. Adhesion molecules play a central role in leucocyte recruitment during inflammation.

AIMS

(1) To determine whether circulating and urinary concentrations of E-selectin and intercellular adhesion molecule 1 (ICAM-1) were abnormal during first documented acute pyelonephritis; (2) to investigate whether circulating or urinary concentrations were predictive for the development of abnormalities on DMSA imaging.

METHODS

Plasma and urine samples were collected from 40 children with a first episode of acute pyelonephritis within one week of infection (acute sample) and at six weeks (late sample). Control samples were collected from 21 healthy age matched controls and 18 age matched controls with febrile illness not secondary to urinary tract infection.

RESULTS

Plasma and urinary sE-selectin were higher in acute samples (median 176.3 ng/ml and 0.12 ng/mmol respectively) compared with late (97.8 ng/ml and 0.029 ng/mmol) and both control (65.6 ng/ml and 0 ng/mmol) and febrile control (urine 0 ng/mmol) samples. Plasma sICAM-1 was higher in acute samples (428 ng/ml) than controls (365.2 ng/ml), and acute sICAM-1 urine concentrations were higher than febrile control concentrations (3.2 v 0.7 ng/mmol). No correlations were detected between sE-selectin or sICAM-1 and acute or late DMSA scan changes.

CONCLUSION

Plasma and urinary sE-selectin and sICAM-1 are significantly increased during acute pyelonephritis, though no correlation exists between the presence of high plasma or urine concentrations and DMSA scan changes, both during acute infection and six weeks post-infection.

Cytokine profiles of pediatric patients treated with antibiotics for pyelonephritis: potential therapeutic impact

Urinary tract infections are common in infants and children. Pyelonephritis may result in serious complications, such as renal scarring, hypertension, and renal failure. Identification of the timing of release of inflammatory cytokines in relation to pyelonephritis and its treatment is essential for designing interventions that would minimize tissue damage. To this end, we measured urinary cytokine concentrations of interleukin-1 beta (IL-1 beta), IL-6, and IL-8 in infants and children with pyelonephritis and in healthy children. Children that presented to our institution with presumed urinary tract infection were given the diagnosis of pyelonephritis if they had a positive urine culture, pyuria, and one or more of the following indicators of systemic involvement: fever, elevated peripheral white blood cell count, or elevated C-reactive protein. Urine samples were obtained at the time of presentation prior to the administration of antibiotics, immediately after completion of the first dose of antibiotics, and at follow up 12 to 24 h after presentation. IL-1 beta, IL-6, and IL-8 concentrations were measured by enzyme-linked immunosorbent assay. Creatinine concentrations were also determined, and cytokine/creatinine ratios were calculated to standardize samples. Differences between pre-antibiotic and follow-up cytokine/creatinine ratios were significant for IL-1 beta, IL-6, and IL-8 (P < 0.01). Differences between pre-antibiotic and control cytokine/creatinine ratios were also significant for IL-1 beta, IL-6, and IL-8 (P < 0.01). Our study revealed that the urinary tract cytokine response to infection is intense but dissipates shortly after the initiation of antibiotic treatment. This suggests that renal damage due to inflammation begins early in infection, underscoring the need for rapid diagnosis and intervention.

[Escherichia coli virulence factors in pediatric urinary tract infections]

As many as 90% of all community-acquired urinary tract infections (UTIs) and more than 30% of nosocomially acquired UTIs are caused by E coli. The migration of bacteria into proximal urethra and bladder mucosa requires that the organisms travel "upstream" and resist being carried away by the flow of urine. Colonisation requires binding of specific adhesions of the bacteria to appropriate receptors on the surfaces of the epithelial cells. P fimbrae are found in 80%, 30% and 20% of strains from patients with pyelonephritis, cystitis and asymptomatic bacteriura, respectively. P fimbrae are found in only 30% of strains isolated from patients with pyelonephritis associated with compromising host factors such as vesicoureteral reflux, urinary tract anatomical abnormalities and recent urinary tract instrumentation.

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.

Are younger children at highest risk of renal sequelae after pyelonephritis?

BACKGROUND

The general belief about the relation between risk of renal sequelae after pyelonephritis and age is that infants are at highest risk and children older than 5 years at lower risk. This assumption has led to differences in treatment based on age. The aim of this prospective study was to investigate the occurrence of renal lesions in children aged 0-16 years.

METHODS

Between May, 1994, and January, 1996, all children aged 0-16 years who were admitted to our department with a diagnosis of probable pyelonephritis and a positive urine culture were included in this prospective study. All patients received antibiotics for 7-21 days. During the acute phase of urinary-tract infection, scintigraphy with technetium-99m-dimercaptosuccinic acid (DMSA) and ultrasonography were done. Voiding cystourethrography was undertaken at least 6 weeks after the end of antibiotic treatment. When scintigraphy showed renal parenchymal lesions, repeat scintigraphy was done after at least 2 months to assess the progression of renal lesions. For the analysis, children were grouped by age according to presumed risk of renal sequelae after pyelonephritis: high risk (< 1 year), moderate risk (1-5 years), low risk (> 5 years).

FINDINGS

201 patients were enrolled in the study (119 < 1 year, 47 aged 1-5 years, 35 > 5 years). During the acute phase of urinary-tract infection, renal lesions were found in 66 (55%) infants under 1 year, in 37 (79%) children aged 1-5 years, and in 24 (69%) children older than 5 years. Of these 127 children, 108 underwent repeat scintigraphy after an average of 3 months (50 < 1 year, 36 aged 1-5 years, 22 > 5 years). Overall, renal scars were found on repeat scintigraphy in 20 (40%) infants under 1 year, in 31 (86%) children aged 1-5 years, and in 14 (64%) children older than 5 years. 38 (36%) of these 65 patients had vesicoureteric reflux. Among 88 children who had a first documented urinary-tract infection and underwent repeat scintigraphy, renal scars were found in 20 (43%) under 1 year, in 26 (84%) aged 1-5 years, and in eight (80%) older than 5 years.

INTERPRETATION

This study did not confirm the conventional view that the risk of renal scars after pyelonephritis diminishes with age. We believe that all children, irrespective of age, will benefit from any measure that prevents the development of renal sequelae.

The possible role of granulocyte elastase in renal damage from acute pyelonephritis

During acute inflammatory processes, extracellular release of granulocyte elastase can contribute to subsequent tissue damage. To test our hypothesis that extracellular elastase release during acute pyelonephritis may contribute to subsequent renal parenchymal damage, we compared the intracellular and extracellular activities of the lysozyme elastase of human polymorphonuclear cells (PMN) when incubated in vitro with bacterial strains causing renal infection that led to either renal damage or no damage. Urine bacterial cultures were obtained from patients with acute pyelonephritis (flank pain, costovertebral angle tenderness, fever > 38 degrees C, bacteriuria, pyuria, and leukocytosis). Renal damage was demonstrated by cortical scarring on followup intravenous pyelography and/or diminished function on 131iodine hippuran renal scan. Mean extracellular elastase activity (mu units/PMN) was 0.15 for unstimulated PMN, 0.07 for PMN stimulated by bacteria not associated with renal damage, and 1.20 for the PMN stimulated by strains associated with renal damage. Mean intracellular elastase activity (mu units/PMN) was 3.73 for unstimulated PMN, 3.48 for PMN stimulated by bacteria not associated with renal damage, and 3.31 for the PMN stimulated by strains associated with renal damage. Extracellular granulocyte elastase activity was thus significantly higher (P = 0.0001) in PMN stimulated by bacterial strains associated with renal damage. Extracellular release of elastase may contribute to the pathogenesis of renal damage in pyelonephritis.

Mechanisms of polymorphonuclear leukocyte mediated peritoneal mesothelial cell injury

To determine the susceptibility of human peritoneal mesothelial cells to injury mediated by activated polymorphonuclear leukocytes (PMNs), we exposed cultured human peritoneal mesothelial cells to 1250, 2500, 3750, and 5000 PMNs/mm3 activated with 50 ng/ml phorbol myristate acetate (PMA) or with 10(-7) FMLP/cytochalasin B for one to five hours. PMN adhesion to mesothelial cells was determined with radiolabeled PMNs. Mesothelial cell injury was determined in five different cell lines by measuring ATP depletion and 51chromium release. In each mesothelial cell line, PMN adhesion was significantly (P < 0.001) increased when PMNs were activated; 64 +/- 1.0 to 92.5 +/- 7.0% of the activated PMNs were adherent to mesothelial cells compared to 6 +/- 1.8 to 27 +/- 2.4% of resting PMNs. Mesothelial cells responded to PMN mediated injury with a fall in ATP levels and 51chromium release that was significant (P < 0.05) by three to four hours. At five hours, ATP levels were markedly depressed to 5 to 41% of control values. Increasing concentrations of activated PMNs caused significantly (P < 0.05) greater mesothelial cell injury as determined by ATP depletion and 51chromium release. PMN adhesion, ATP depletion and 51chromium release were significantly (P < 0.01) prevented by an anti-CD18 monoclonal antibody that inhibits the CD11/CD18 adhesion molecule complex on PMNs. Similar injury and protection from injury was demonstrated when mesothelial cells were exposed to PMNs activated with FMLP/cytochalasin B.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin-6 and interleukin-8 in the urine of children with acute pyelonephritis

Interleukin-6 (IL-6) and interleukin-8 (IL-8) are important mediators of the inflammatory response in serious bacterial infections. We studied the levels of these two cytokines (standardised for urinary creatinine) in the urine of infants and children during and 6 weeks after acute pyelonephritis and in non-renal febrile controls and healthy children without apparent infection. IL-6 was detected in the urine of 52% of children with pyelonephritis compared with 15% of other children (P < 0.001). The median urinary IL-6 level in acute pyelonephritis was 4 pg/mumol compared with undetectable levels in the control group (P < 0.001). IL-8 was detected in 98% of children with pyelonephritis and 42% of other children (P < 0.001). The median concentration of IL-8 was 188 pg/mumol in pyelonephritis; it was undetectable in controls (P < 0.001). IL-8 levels were higher in children less than 1 year of age (P < 0.001).

Renal scarring after acute pyelonephritis

Seventy six children, 18 boys and 58 girls, aged 0-15.9 (median 1.0) years, with acute pyelonephritis were prospectively studied with a technetium-99m dimercaptosuccinic acid (DMSA) scan during infection and two months later. Fifty nine of these children were also studied two years after the infection. Seventeen children with a normal DMSA scan during infection or at two months after infection, or both, were not investigated by a DMSA scan at two years after acute pyelonephritis. A micturition cystourethrogram was performed in all the children after two months. Changes on the DMSA scan were found in 65 (86%) children during acute pyelonephritis, in 45 (59%) children at two months, and in 28 (37%) children at two years after infection. Vesicoureteric reflux (VUR) was found in 19 (25%) children at two months. Renal scarring was significantly correlated with the presence of gross VUR and recurrent pyelonephritis, but 62% of the scarred kidneys were drained by non-refluxing ureters. Children with scars were older at the time of acute pyelonephritis than those without scars but no difference was found between the groups with regard to duration of illness, levels of C reactive protein and maximum white cell count, glomerular filtration rate, nor renal concentration capacity at the time of infection. It is concluded that renal scarring after acute pyelonephritis in children is more common than has been previously thought. Although children with gross VUR and recurrent pyelonephritis are at the greatest risk, renal scarring is more often seen without these risk factors.

Cortical scintigraphy in the evaluation of renal parenchymal changes in children with pyelonephritis

We designed a prospective study to evaluate the ability of dimercaptosuccinic acid cortical scintigraphy and ultrasonography to detect renal parenchymal lesions in children with pyelonephritis. One hundred eleven patients 1 week to 16 years of age (median 5.5 months) with a urine culture positive for pathogens were included in the study; cortical scintigraphy and ultrasonography were repeated in 25 children after a mean follow-up of 10.5 months. Cortical scintigraphy showed renal changes in 74 children (67%), and ultrasonography showed renal changes in 39 (35%) (p < 0.001); results of the two examinations were discordant in 49 patients (kappa = 0.19). Children more than 1 year of age had a higher incidence of renal lesions than did younger children (85% vs 66%; p = 0.04). The presence of inflammatory signs (erythrocyte sedimentation rate or C-reactive protein) had an 89% sensitivity and a 25% specificity in identifying renal lesions. Among children with renal changes, vesicoureteric reflux was present in 39%. At follow-up examination, 16 children (64%) had scars. Thus we found a high incidence of renal involvement in children with pyelonephritis. We found that cortical scintigraphy is more sensitive than ultrasonography in detecting renal changes, and we believe that it should be added to the initial examination of children with suspected pyelonephritis.