Suprapubic aspiration under ultrasound guidance in children with fever of undiagnosed cause

Urinary tract infection in pediatrics: an overview

OBJECTIVE

This review aimed to provide a critical overview on the pathogenesis, clinical findings, diagnosis, imaging investigation, treatment, chemoprophylaxis, and complications of urinary tract infection in pediatric patients.

SOURCE OF DATA

Data were obtained independently by two authors, who carried out a comprehensive and non-systematic search in public databases.

SUMMARY OF FINDINGS

Urinary tract infection is the most common bacterial infection in children. Urinary tract infection in pediatric patients can be the early clinical manifestation of congenital anomalies of the kidney and urinary tract (CAKUT) or be related to bladder dysfunctions. E. coli is responsible for 80-90% of community-acquired acute pyelonephritis episodes, especially in children. Bacterial virulence factors and the innate host immune systems may contribute to the occurrence and severity of urinary tract infection. The clinical presentation of urinary tract infections in children is highly heterogeneous, with symptoms that can be quite obscure. Urine culture is still the gold standard for diagnosing urinary tract infection and methods of urine collection in individual centers should be determined based on the accuracy of voided specimens. The debate on the ideal imaging protocol is still ongoing and there is tendency of less use of prophylaxis. Alternative measures and management of risk factors for recurrent urinary tract infection should be emphasized. However, in selected patients, prophylaxis can protect from recurrent urinary tract infection and long-term consequences. According to population-based studies, hypertension and chronic kidney disease are rarely associated with urinary tract infection.

CONCLUSION

Many aspects regarding urinary tract infection in children are still matters of debate, especially imaging investigation and indication of antibiotic prophylaxis. Further longitudinal studies are needed to establish tailored approach of urinary tract infection in childhood.

Update on the approach of urinary tract infection in childhood

OBJECTIVE

Urinary tract infection (UTI) is the most common bacterial infection in childhood. UTI may be the sentinel event for underlying renal abnormality. There are still many controversies regarding proper management of UTI. In this review article, the authors discuss recent recommendations for the diagnosis, treatment, prophylaxis, and imaging of UTI in childhood based on evidence, and when this is lacking, based on expert consensus.

SOURCES

Data were obtained after a review of the literature and a search of Pubmed, Embase, Scopus, and Scielo.

SUMMARY OF THE FINDINGS

In the first year of life, UTIs are more common in boys (3.7%) than in girls (2%). Signs and symptoms of UTI are very nonspecific, especially in neonates and during childhood; in many cases, fever is the only symptom.

CONCLUSIONS

Clinical history and physical examination may suggest UTI, but confirmation should be made by urine culture, which must be performed before any antimicrobial agent is given. During childhood, the proper collection of urine is essential to avoid false-positive results. Prompt diagnosis and initiation of treatment is important to prevent long-term renal scarring. Febrile infants with UTIs should undergo renal and bladder ultrasonography. Intravenous antibacterial agents are recommended for neonates and young infants. The authors also advise exclusion of obstructive uropathies as soon as possible and later vesicoureteral reflux, if indicated. Prophylaxis should be considered for cases of high susceptibility to UTI and high risk of renal damage.

Urinalysis in children and adolescents

BACKGROUND

Urinalysis is the most commonly performed biochemical test in infancy and early childhood. The urine sample should be correctly obtained, age-specific aspects should be considered, and age-dependent reference values should be used.

METHOD

This review is based on a selective literature search in electronic databases, textbooks, and guidelines from Germany and abroad on the acquisition of urine samples and the performance of urinalysis in infancy and early childhood.

RESULTS

The timing and mode of acquisition of the urine sample affect the assessment of hematuria, proteinuria, leukocyturia, nitrituria, and the uropathogenic bacterial colony count in the urine culture. Dipstick tests can be used for targeted screening for these features. The test results should be interpreted together with the findings of urine microscopy, the medical history, and the physical examination. Proteinuria should be quantified and differentiated; both of these things can be done either from collected urine or (especially in infants and young children) from a spontaneously voided urine sample, by determination of the protein/creatinine quotient. Orthostatic proteinuria in an adolescent requires no further evaluation or treatment. Hematuria should be characterized as either glomerular or non-glomerular erythrocyturia. Asymptomatic, isolated microhematuria in childhood is not uncommon and often transient; in the absence of a family history, it usually does not require an extensive work-up. Proteinuria combined with hematuria should arouse the suspicion of glomerulonephritis.

CONCLUSION

Urinalysis in infancy and early childhood is a simple and informative diagnostic test as long as the urine sample has been obtained properly and the results are interpreted appropriately for this age group.

Urinary tract infections in children: EAU/ESPU guidelines

CONTEXT

In 30% of children with urinary tract anomalies, urinary tract infection (UTI) can be the first sign. Failure to identify patients at risk can result in damage to the upper urinary tract.

OBJECTIVE

To provide recommendations for the diagnosis, treatment, and imaging of children presenting with UTI.

EVIDENCE ACQUISITION

The recommendations were developed after a review of the literature and a search of PubMed and Embase. A consensus decision was adopted when evidence was low.

EVIDENCE SYNTHESIS

UTIs are classified according to site, episode, symptoms, and complicating factors. For acute treatment, site and severity are the most important. Urine sampling by suprapubic aspiration or catheterisation has a low contamination rate and confirms UTI. Using a plastic bag to collect urine, a UTI can only be excluded if the dipstick is negative for both leukocyte esterase and nitrite or microscopic analysis is negative for both pyuria and bacteriuria. A clean voided midstream urine sample after cleaning the external genitalia has good diagnostic accuracy in toilet-trained children. In children with febrile UTI, antibiotic treatment should be initiated as soon as possible to eradicate infection, prevent bacteraemia, improve outcome, and reduce the likelihood of renal involvement. Ultrasound of the urinary tract is advised to exclude obstructive uropathy. Depending on sex, age, and clinical presentation, vesicoureteral reflux should be excluded. Antibacterial prophylaxis is beneficial. In toilet-trained children, bladder and bowel dysfunction needs to be excluded.

CONCLUSIONS

The level of evidence is high for the diagnosis of UTI and treatment in children but not for imaging to identify patients at risk for upper urinary tract damage.

PATIENT SUMMARY

In these guidelines, we looked at the diagnosis, treatment, and imaging of children with urinary tract infection. There are strong recommendations on diagnosis and treatment; we also advise exclusion of obstructive uropathy within 24h and later vesicoureteral reflux, if indicated.

Pediatric urinary tract infections

Urinary tract infections (UTIs) in children are commonly seen in the emergency department and pose several challenges to establishing the proper diagnosis and determining management. This article reviews pediatric UTI and addresses epidemiology, diagnosis, treatment, and imaging, and their importance to the practicing emergency medicine provider. Accurate and timely diagnosis of pediatric UTI can prevent short-term complications, such as severe pyelonephritis or sepsis, and long-term sequelae including scarring of the kidneys, hypertension, and ultimately chronic renal insufficiency and need for transplant.

Urinary tract infection: clinical practice guideline for the diagnosis and management of the initial UTI in febrile infants and children 2 to 24 months

OBJECTIVE

To revise the American Academy of Pediatrics practice parameter regarding the diagnosis and management of initial urinary tract infections (UTIs) in febrile infants and young children.

METHODS

Analysis of the medical literature published since the last version of the guideline was supplemented by analysis of data provided by authors of recent publications. The strength of evidence supporting each recommendation and the strength of the recommendation were assessed and graded.

RESULTS

Diagnosis is made on the basis of the presence of both pyuria and at least 50,000 colonies per mL of a single uropathogenic organism in an appropriately collected specimen of urine. After 7 to 14 days of antimicrobial treatment, close clinical follow-up monitoring should be maintained to permit prompt diagnosis and treatment of recurrent infections. Ultrasonography of the kidneys and bladder should be performed to detect anatomic abnormalities. Data from the most recent 6 studies do not support the use of antimicrobial prophylaxis to prevent febrile recurrent UTI in infants without vesicoureteral reflux (VUR) or with grade I to IV VUR. Therefore, a voiding cystourethrography (VCUG) is not recommended routinely after the first UTI; VCUG is indicated if renal and bladder ultrasonography reveals hydronephrosis, scarring, or other findings that would suggest either high-grade VUR or obstructive uropathy and in other atypical or complex clinical circumstances. VCUG should also be performed if there is a recurrence of a febrile UTI. The recommendations in this guideline do not indicate an exclusive course of treatment or serve as a standard of care; variations may be appropriate. Recommendations about antimicrobial prophylaxis and implications for performance of VCUG are based on currently available evidence. As with all American Academy of Pediatrics clinical guidelines, the recommendations will be reviewed routinely and incorporate new evidence, such as data from the Randomized Intervention for Children With Vesicoureteral Reflux (RIVUR) study.

CONCLUSIONS

Changes in this revision include criteria for the diagnosis of UTI and recommendations for imaging.

Technical report—Diagnosis and management of an initial UTI in febrile infants and young children

OBJECTIVES

The diagnosis and management of urinary tract infections (UTIs) in young children are clinically challenging. This report was developed to inform the revised, evidence-based, clinical guideline regarding the diagnosis and management of initial UTIs in febrile infants and young children, 2 to 24 months of age, from the American Academy of Pediatrics Subcommittee on Urinary Tract Infection.

METHODS

The conceptual model presented in the 1999 technical report was updated after a comprehensive review of published literature. Studies with potentially new information or with evidence that reinforced the 1999 technical report were retained. Meta-analyses on the effectiveness of antimicrobial prophylaxis to prevent recurrent UTI were performed.

RESULTS

Review of recent literature revealed new evidence in the following areas. Certain clinical findings and new urinalysis methods can help clinicians identify febrile children at very low risk of UTI. Oral antimicrobial therapy is as effective as parenteral therapy in treating UTI. Data from published, randomized controlled trials do not support antimicrobial prophylaxis to prevent febrile UTI when vesicoureteral reflux is found through voiding cystourethrography. Ultrasonography of the urinary tract after the first UTI has poor sensitivity. Early antimicrobial treatment may decrease the risk of renal damage from UTI.

CONCLUSIONS

Recent literature agrees with most of the evidence presented in the 1999 technical report, but meta-analyses of data from recent, randomized controlled trials do not support antimicrobial prophylaxis to prevent febrile UTI. This finding argues against voiding cystourethrography after the first UTI.

Risk factors for contamination of catheterized urine specimens in febrile children

BACKGROUND

Urinary tract infections are the most common serious bacterial infection in febrile infants. Bladder catheterization is the preferred method of obtaining urine for culture in young children. Contamination of urine can be recognized when nonpathogens or multiple pathogens are isolated; preliminary culture results may lead to unnecessary antibiotics pending final identification. Some low-colony count (<50,000 colony-forming units per milliliter) cultures may represent contamination or asymptomatic bacteriuria.

OBJECTIVE

Identify clinical factors that lead to contamination of catheterized urine specimens.

METHODS

Physicians and nurses in an urban pediatric emergency department completed a survey after performing bladder catheterization of febrile children 36 months or younger. Contamination was defined by multiple pathogens, nonpathogens, or colony counts less than 10,000 colony-forming units per milliliter.

RESULTS

: One hundred eighty-five children were studied. The median age was 8.4 months (interquartile range, 2.4-14.4 months). Sixty-eight percent were girls. Forty-six percent of boys were circumcised. Of the 185 children, 18 (10%) had true UTI. Fourteen percent of cultures were contaminated. Univariate analysis of potential predictors identified age younger than 6 months (odds ratio [OR], 6.8; 95% confidence interval [CI], 2.6-17.9), difficult catheterization (OR, 3.6; 95% CI, 1.5-8.6), and uncircumcised boys (OR, 5.7; 95% CI, 1.2-29.4). The contamination rate in uncircumcised boys younger than 6 months was 43% (95% CI, 26-66). Volume of urine, sex, and catheter size were not predictive of contamination.

CONCLUSIONS

Children younger than 6 months and uncircumcised boys are at increased risk of contaminated specimens from bladder catheterization. Suprapubic aspiration or use of a fresh, sterile catheter with each repeated attempt at catheterization may lead to less contamination in these patients.

Absolute and relative accuracy of rapid urine tests for urinary tract infection in children: a meta-analysis

Rapid urine tests, such as microscopy, for bacteria and white cells, and dipsticks, for leucocyte esterase and nitrites, are often used in children that are unwell to guide early diagnosis and treatment of urinary tract infection. We aimed to establish whether these tests were sufficiently sensitive to avoid urine culture in children with negative results and to compare the accuracy of dipsticks with microscopy. Medline, Embase, and reference lists were searched. Studies were included if urine culture results were compared with rapid tests in children. Data were analysed to obtain absolute and relative accuracy estimates. Data from 95 studies in 95 703 children were analysed. Summary estimates for sensitivity and specificity for microscopy for Gram-stained bacteria were 91% (95% CI 80-96) and 96% (92-98), for unstained bacteria were 88% (75-94) and 92% (84-96), for urine white cells were 74% (67-80) and 86% (82-90), for leucocyte esterase or nitrite positive dipstick were 88% (82-91) and 79% (69-87), and for nitrite-only positive dipstick were 49% (41-57) and 98% (96-99). Microscopy for bacteria with Gram stain had higher accuracy than other laboratory tests with relative diagnostic odds ratio compared with bacteria without Gram stain of 8.7 (95% CI 1.8-41.1), white cells of 14.5 (4.7-44.4), and nitrite of 22.0 (0.7-746.3). Microscopy for white cells should not be used for the diagnosis of urinary tract infection because its accuracy is no better than that of dipstick, laboratory facilities are needed, and results are delayed. Rapid tests are negative in around 10% of children with a urinary tract infection and cannot replace urine culture. If resources allow, microscopy with Gram stain should be the single rapid test used.

Effect of confounding in the association between circumcision status and urinary tract infection

OBJECTIVES

To estimate the impact of confounding in the association between circumcision status and urinary tract infection from epidemiological factors, sample collection, and health-seeking behaviors in the first year of life.

METHODS

Beginning with the assumption that true urinary tract infection occurred equally regardless of circumcision status, a Markov model incorporating the differences in the rates of prematurity, of urine collection, of false positive urine specimens, and of health-seeking behaviors in infant boys based on circumcision status was developed. Using this model, the rates of false-positive urine cultures, asymptomatic bacteriuria, and true urinary tract infection detected in the first year of life were estimated and contrasted. Error of the model was estimated using Monte Carlo simulations.

RESULTS

Keeping the incidence of true urinary tract infection constant between groups, the factors included in the model could account for urinary tract infection being diagnosed 4.27 times more frequently in non-circumcised males under a year of age.

CONCLUSIONS

Previously reported differences in the rate of urinary tract infection by circumcision status could be entirely due to sampling and selection bias. Until clinical studies adequately control for sources of bias, circumcision should not be recommended as a preventive for urinary tract infection.

Low bacterial count urinary tract infections in infants and young children

The purpose of the study was to compare bacterial species, clinical, laboratory and imaging findings ((99m )Tc-dimercaptosuccinic acid renal scan and voiding cystogram) in infants and children with high (>/=10(5) colony forming units (CFU)/ml, group A patients) and low (</=5 x 10(4) CFU/ml, group C patients) bacterial count in urine cultures during first episode of urinary tract infection. Group B included patients with intermediate CFU/ml. Included were 419 symptomatic patients with: (a) no previous antibiotic treatment, (b) urine samples for quantitative cultures taken by bladder catheterisation or suprapubic bladder aspiration, (c) growth of only one microorganism, and (d) age </=54 months (age of the oldest patient of group C). Out of 419 cultures, Escherichia coli grew in 315 (75.2%), gram-negative bacteria except E. coli in 91 (21.7%) and gram-positive in 13 (3.1%). Group C patients were significantly ( P <0.0001) more often affected with gram-negative pathogens except E. coli than group A patients (21/44 versus 67/360). Most of group C patients were younger than 24 months of age; none was older than 54 months. Comparison of the prevalence of clinical and laboratory (leucocyte count, CRP, ESR) findings between groups A and C showed no significant differences. There was no statistically significant difference in the prevalence of pyelonephritis, reflux and urological malformations (except reflux) between groups A and C.

CONCLUSION

Low bacterial count urinary tract infections mainly affect infants and young children and are often due to gram-negative bacteria other than E. coli. Clinical and laboratory findings, prevalence of pyelonephritis, reflux and urological malformations are similar in high and low bacterial count urinary tract infections.

Parental reporting of smelly urine and urinary tract infection

BACKGROUND

Parents often report that young children have "smelly urine" or a particular urinary odour. There is little evidence that these observations are relevant to the diagnosis of urinary tract infection (UTI).

AIMS

To determine whether parental reporting of smelly urine is of any relevance to the diagnosis of UTI in children less than 6 years of age.

METHODS

Parents whose children were having urine collected as part of their admission to a large district hospital were given a simple questionnaire to complete regarding the current smell of their child's urine. Parents were asked whether their child's urine smelled different from usual or had a particular smell. Microscopy and culture results of the child's urine were compared to their parent's questionnaire answers to see if there was a association between parental reporting of a different or particular urine smell and a diagnosis of UTI.

RESULTS

One hundred and ten questionnaires and urine samples were obtained. Fifty two per cent of parents thought that their child's urine smelled different from usual or had a particular smell. Only 6.4% of children were diagnosed as having a UTI. There was no statistically significant association between parental reporting of abnormal urine smell and diagnosis of UTI.

CONCLUSION

In determining whether a young child has a UTI, asking parents about urine smell is unlikely to be of benefit.

Sterile pyuria: a differential diagnosis

Sterile pyuria is not an uncommon laboratory finding. This article explores the major causes of sterile pyuria, including infectious, systemic, structural and physiologic, and drug-related causes. It also discusses the differential diagnosis of eosinophiluria and the basic workup of sterile pyuria.

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

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

Accuracy of clean-catch urine collection in infancy

OBJECTIVE

To compare the accuracy of cultures of urine obtained by clean-catch urine (CCU) collection and suprapubic aspiration (SPA) in infants.

DESIGN

Prospective case series undertaken in a pediatric teaching hospital and associated neonatal unit. Fifty-eight paired urine cultures (CCU collection and SPA) were obtained from 49 infants with suspected urinary tract infection. The primary outcome measure was the presence or absence of significant bacteriuria on both CCU collection and SPA; secondary outcome measures were the success of SPA with ultrasound guidance compared with aspiration without ultrasound guidance. Statistical analysis was done by using a chi(2) test.

RESULTS

A false-positive rate of 5% and a false-negative rate of 12% were recorded. Sensitivity was 88.9% (95% CI 65.3-98.6), and specificity was 95.0% (95 CI% 83.1-99. 4). Ultrasound-assisted SPA was successful in 26 of 28 patients (93%) and in 13 of 21 patients (62%) when SPA was performed without ultrasound (chi(2) = 7.08, P =.008).

CONCLUSIONS

We conclude that there is a good association in results of culture of urine obtained by CCU collection and SPA and would encourage the use of the CCU technique.

Technical report: urinary tract infections in febrile infants and young children. The Urinary Tract Subcommittee of the American Academy of Pediatrics Committee on Quality Improvement

OVERVIEW

The Urinary Tract Subcommittee of the American Academy of Pediatrics Committee on Quality Improvement has analyzed alternative strategies for the diagnosis and management of urinary tract infection (UTI) in children. The target population is limited to children between 2 months and 2 years of age who are examined because of fever without an obvious cause. Diagnosis and management of UTI in this group are especially challenging for these three reasons: 1) the manifestation of UTI tends to be nonspecific, and cases may be missed easily; 2) clean voided midstream urine specimens rarely can be obtained, leaving only urine collection methods that are invasive (transurethral catheterization or bladder tap) or result in nonspecific test results (bag urine); and 3) a substantial number of infants with UTI also may have structural or functional abnormalities of the urinary tract that put them at risk for ongoing renal damage, hypertension, and end-stage renal disease (ESRD).

METHODS

To examine alternative management strategies for UTI in infants, a conceptual model of the steps in diagnosis and management of UTI was developed. The model was expanded into a decision tree. Probabilities for branch points in the decision tree were obtained by review of the literature on childhood UTI. Data were extracted on standardized forms. Cost data were obtained by literature review and from hospital billing data. The data were collated into evidence tables. Analysis of the decision tree was used to produce risk tables and incremental cost-effectiveness ratios for alternative strategies.

RESULTS

Based on the results of this analysis and, when necessary, consensus opinion, the Committee developed recommendations for the management of UTI in this population. This document provides the evidence the Subcommittee used in the development of its recommendations.

CONCLUSIONS

The Subcommittee agreed that the objective of the practice parameter would be to minimize the risk of chronic renal damage within reasonable economic constraints. Steps involved in achieving these objectives are: 1) identifying UTI; 2) short-term treatment of UTI; and 3) evaluation for urinary tract abnormalities.

Should GPs have direct access to imaging for children with urinary tract infections? An observational study

BACKGROUND

All children with urinary tract infections (UTIs) should undergo imaging of the urinary tract. The Royal College of Radiologists currently recommends that such children should be referred to a paediatric specialist prior to imaging.

AIM

To investigate whether direct referral of such children by general practitioners (GPs) for imaging offers advantages over the traditional approach.

METHOD

Information on 100 children with UTIs, who were referred direct for imaging by GPs according to an agreed protocol, was compared with information on 100 children with UTIs referred initially to paediatric specialists.

RESULTS

Protocol-guided direct referral resulted in less delay prior to imaging, no evidence of inappropriate referral (as judged by urinalysis and yield from imaging), greater consistency of follow-up arrangements, and a considerable saving in outpatient department (OPD) appointments. There was no increase in the overall number of referrals for imaging.

CONCLUSION

Given agreed protocols, there is no basis for current recommendations that GPs should not refer children with UTIs for imaging without a prior paediatric opinion.

Low bacterial counts in infants with urinary tract infection

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

Study of urinary tract infection in children in one health district

OBJECTIVES

To determine the number of children who had urine specimens sent for culture, who had infections or sterile pyuria, and who were investigated further. To relate the laboratory findings to the results of imaging.

DESIGN

One year survey of urine specimens submitted to a laboratory; review of previous and subsequent laboratory reports; review of the findings of imaging of the urinary tract.

SETTING

Portsmouth and South East Hampshire health district.

SUBJECTS

An estimated population of 89,086 children aged 12 years or under.

MAIN OUTCOME MEASURES

Urine bacterial count and results of imaging.

RESULTS

12,551 urine specimens were submitted from 7450 children, 3138 boys and 4312 girls. 2238 children had infection or sterile pyuria at least once during the study (13.9/1000 boys, 37/1000 girls). 996 (45%) of the children with infection or sterile pyuria underwent some form of imaging. 128 children who had infection or sterile pyuria were already known to have urinary tract abnormalities and 114 children had newly identified abnormalities (1.0/1000 boys, 1.5/1000 girls). 50 (44%) of the children with newly detected abnormalities had no pyuria and 48 (42%) had bacterial counts below 10(8)/l. Eight children who had sterile pyuria on presentation were found to have abnormalities on imaging.

CONCLUSIONS

Urinary tract infection is much commoner in children than is widely believed. Low bacterial counts, the absence of pyuria, or a finding of sterile pyuria should not be disregarded.