Asymptomatic bacteriuria and vesicoureteral reflux in children

How Swedish guidelines on urinary tract infections in children compare to Canadian, American and European guidelines

Urinary tract infections (UTI) are common in children and the guidelines focus on preventing kidney damage. We compared the 2013 national Swedish guidelines on UTIs in children with the guidelines from America, Canada, UK, Spain, Italy and European urologists. This showed that urinalysis and urine cultures are endorsed by all the guidelines, but sampling techniques and bacteria levels differ. They all recommend initial oral treatment and renal ultrasound to detect major anomalies in infants. The Swedish guidelines are more liberal on antibiotic prophylaxis.

Conclusion

Differences in diagnostic criteria, workup and accepted methods for urine sampling were noted and are discussed.

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.

Highlights for management of a child with a urinary tract infection

Urinary tract infections remain the most common bacterial infection in childhood. Escherichia coli is responsible for over 80% of Pediatric UTIs. Other common gram negative organisms include Kleibsiella, Proteus, Enterobacter and occasionally Pseudomonas. Signs and symptoms vary greatly by age of the patient becoming more specific as the child grows older. Even in the absence of specific signs a UTI should be included in the differential diagnosis of high grade fever. In younger children, presence of upper respiratory infections, otitis media or gastroenteritis does not eliminate the possibility of a UTI. Culture of the urine remains the gold standard for diagnosing UTIs. All males and females with well documented UTIs should be imaged for the presence of urological anomalies associated with UTI. Depending on patient's clinical symptoms and tolerance, therapy can be oral or parenteral as they have both been found equally efficacious. Healthcare professionals should ensure that when a child or young person has been identified as having a suspected UTI, they and their parents are given information about the need for treatment, the importance of completing any course of treatment and advice about prevention and possible long-term management.

Relationships among vesicoureteric reflux, urinary tract infection and renal injury in children with non-neurogenic lower urinary tract dysfunction

OBJECTIVE

To determine the relationship between vesicoureteric reflux (VUR), urinary tract infection (UTI), renal damage and the pattern of non-neurogenic lower urinary tract dysfunction (LUTD), and to reveal the possible risk factors for renal damage in children with LUTD.

METHODS

For the years 2004-2010, demographic, clinical, laboratory and urodynamic study reports of children with LUTD were retrospectively reviewed.

RESULTS

Of 96 patients, there were diagnosed 70 with overactive bladder (OAB), 8 pure dysfunctional voiding (DV) and 18 OAB plus DV. The rate of VUR, UTI and renal damage in patients with OAB plus DV and pure DV was higher than in patients with OAB alone. VUR was significantly higher among the patients who had UTI. Renal scarring was detected in 25 patients, of whom 78% had OAB plus DV and 75% DV. The presence of VUR was associated with a significant increase in the rate of renal damage, and dilating reflux caused significantly greater damage compared to non-dilating reflux.

CONCLUSION

OAB plus DV and DV are major risk factors for VUR, UTI and renal damage. The presence of VUR in children with LUTD plays an important role with regard to UTI and renal damage, with dilating VUR a major risk factor associated with renal damage.

Managing urinary tract infections

Urinary tract infections (UTI) are common in childhood. Presence of pyuria and bacteriuria in an appropriately collected urine sample are diagnostic of UTI. The risk of UTI is increased with an underlying urological abnormality such as vesicoureteral reflux, constipation, and voiding dysfunction. Patients with acute pyelonephritis are at risk of renal scarring and subsequent complications such as hypertension, proteinuria with and without FSGS, pregnancy-related complications and even end-stage renal failure. The relevance and the sequence of the renal imaging following initial UTI, and the role of antimicrobial prophylaxis and surgical intervention are currently undergoing an intense debate. Prompt treatment of UTI and appropriate follow-up of those at increased risk of recurrence and/or renal scarring are important.

Risk factors for renal scarring in children and adolescents with lower urinary tract dysfunction

Risk factors for renal scarring in children with lower urinary tract dysfunction (LUTD) were evaluated. The medical records of 120 patients were assessed concerning gender, presence of vesicoureteric reflux (VUR), bladder capacity, detrusor overactivity, residual urine, febrile urinary tract infection (UTI), bacteriuria, constipation, detrusor sphincter incoordination (DSI), high detrusor pressure at maximal cystometric capacity (PMCC), low compliance, and thickness and trabeculation of the bladder wall. Renal scarring was diagnosed by (99m)technetium-dimercaptosuccinic acid renal scan (DMSA). Renal scarring was detected in 38 patients (31%). VUR, UTI, decreased bladder capacity, urinary residue, and trabeculated and thick bladder wall were associated with scarring at univariate analysis. Multivariate analysis showed VUR (P < 0.0001) as the independent risk factor for renal scarring. Thickness of the bladder wall was a marginal risk factor (P = 0.07). Although UTI was not a risk factor, it was associated with VUR (P = 0.03). In our analysis, VUR was the main risk factor; however, renal scarring was probably due to multifactorial causes, as VUR was associated with UTI.

Management of urinary tract infections

Urinary tract infection (UTI) is common in childhood. It may result in long-term complications due to renal scaring. Younger children are at higher risk of renal scarring. The diagnosis of UTI is based on urine culture. The bacterial count for diagnosis of UTI depends on the method of urine collection. Urinalysis is useful for making a presumptive diagnosis of UTI and allows initiation of empirical treatment in high-risk patients, after urine culture has been obtained. The treatment of UTI is guided by the severity of illness and age of the patient. Following a UTI, investigation should be performed to identify an underlying urinary tract anomaly. Recurrence of UTI occurs in 30-50% children. Important predisposing factors include VUR, urinary tract obstruction, voiding dysfunction and constipation. Vesicoureteric reflux (VUR) is seen in 30-50% children with UTI. The cornerstone of management of VUR is long-term antibiotic prophylaxis, which has been found to be as effective as surgical reimplantation.

Is bag urine culture useful in monitoring urinary tract infection in infants?

OBJECTIVES

We studied the false-positive rate of bag urine cultures in diagnosing bacteriuria in infants and examined the factors responsible for contamination.

METHODS

One hundred asymptomatic patients with previous urinary tract infections (UTI; age range 5-23 months; sex ratio M : F 73:27) were screened by bag urine cultures and confirmed by suprapubic aspiration or catheterization. Those producing contaminated and clean samples were interviewed with a standard questionnaire.

RESULTS

Sixty patients had insignificant growth and 40 had doubtful or mixed growth. After further interview and instructions, the latter group produced a second bag urine sample with negative results in 23 and positive results in 17. Among the latter, UTI was confirmed in five and excluded in 12 cases. The false-positive rate of first urine collection was 36.8%. Comparing patients with contaminated urine to those with negative urine samples, we found the former were associated with waiting for more than one void to complete urine collection, and with uncircumcised boys. Other factors did not reach statistical significance. Proper counselling and repeating a second culture reduced the overall false-positive rate to 12.6%.

CONCLUSION

In our population, the contamination rate of one bag urine culture was 36.8%, which is unacceptable and alternative methods need to be sought. Contamination was associated with improper collection procedures and with uncircumcised boys. Proper instructions and doing a second urine culture reduced the overall rate to 12.6%, but at the expense of delaying diagnosis and treatment.

[Urinary antimicrobial prophylaxis]

Antibiotics are usually used to prevent childhood recurrent urinary tract infections: cystitis or pyelonephritis. The mechanism of action of these antibiotics, although imperfectly known, seems to be double: the antibiotic acts by its bactericidal effect, but also probably for minimal concentrations by reducing adhesion capability of bacteria to the urothelium. The most commonly used molecules are cotrimoxazole, trimethoprime, pivmecillinam, cefaclor and nalidixic acid. However all have not been studied rigorously as for their prophylactic capacity, and in particular very little is known for patients presenting with vesico-ureteral reflux.

Antibacterial prophylaxis in children with urinary tract infection

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

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

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

The epidemiology and clinical presentation of urinary tract infections in children younger than 2 years of age

UTI in young infants generally presents with fever. Among the youngest infants, boys and girls are equally affected. The incidence of UTI in uncircumcised boys is comparable with that in girls, whereas the rate in circumcised boys is much lower. Based on gender and race, white girls have the highest incidence of UTI. A full understanding of the epidemiology of UTI is complicated by the presence of asymptomatic bacteriuria and by incomplete evidence regarding the significance of scarring and the risk of sequelae.

Urinary tract infections in children. Epidemiology, evaluation, and management

Accurate documentation of UTIs in children is essential for proper evaluation and management. Urine cultures with multiple organisms or colony counts less than 50,000 to 100,000 CFU/ml should be considered suspect and require confirmation, particularly with clean-catch specimens. Children with well-documented UTIs should be evaluated based on their age and presenting symptoms. Infants and young children require imaging, usually with a cystogram and sonogram of the kidneys and bladder. Older girls with febrile UTIs and boys at any age should also be considered for urinary tract imaging. Renal cortical scintigraphy with 99mTc-DMSA has emerged as the imaging study of choice for acute pyelonephritis and renal scarring in children with UTIs. Treatment of UTIs in children ideally commences with culture-specific antimicrobial therapy, although treatment may be started in sick children before culture results are available. Short-course treatment (3-5 days) is sufficient for children with acute uncomplicated lower UTIs. Children with acute pyelonephritis require 10 to 14 days of antibiotics, which can be administered on an outpatient basis in older infants and children who are not toxic, as long as good compliance is expected. Patients with first-time UTIs who require imaging should be maintained on low-dose antibiotic prophylaxis until their workup is completed. Treatment of ABU does not seem necessary if the urinary tract is otherwise normal. Long-term antibiotic prophylaxis is indicated for children with frequent symptomatic recurrences of UTI and for those with known VUR. Diagnosis and treatment of underlying voiding dysfunction and constipation is an essential component of the successful management of UTIs in children.

The natural history of bacteriuria in childhood

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