Update on Childhood Urinary Tract Infection and Vesicoureteral Reflux

https://doi.org/10.1016/j.semnephrol.2009.03.011Get rights and content

Summary

Urinary tract infection (UTI) is a leading cause of serious bacterial infection in young children. Vesicoureteral reflux (VUR), a common pediatric urologic disorder, is believed to predispose to UTI, and both are associated with renal scarring. The complex interaction of bacterial virulence factors and host defense mechanisms influence renal damage. However, some renal parenchymal abnormalities associated with VUR are noninfectious in origin. Long-term, renal parenchymal injury may be associated with hypertension, pregnancy complications, proteinuria, and renal insufficiency. Optimal management of VUR and UTI is controversial because of the paucity of appropriate randomized controlled trials; there is a need for well-designed studies. The recently launched Randomized Intervention for children with VesicoUreteral Reflux (RIVUR) study hopefully will provide insight into the role of antimicrobial prophylaxis of UTI in children with VUR.

Section snippets

Pathogenesis

Urinary infection usually is ascending, with inoculation of fecally derived organisms from the urethra and peri-urethral tissues into the bladder.4 The most prevalent pathogens in several recent pediatric studies were Escherichia coli (54%-67%), Klebsiella (6%-17%), Proteus (5%-12%), Enterococcus (3%-9%) and Pseudomonas (2%-6%).5, 6, 7 Previously, E coli accounted for 80% to 90% of infections, and it is not clear if the change in frequency was caused by sampling bias (not all infections

Clinical Presentation

Young infants often present with fever alone (≥38°C); irritability, vomiting, lethargy, or poor feeding variably may be present. For those younger than 3 months there is an increased risk of bacteremia and a greater possibility of undiagnosed congenital urologic malformations.15 Older children generally have more explicit symptoms of bladder inflammation and/or flank pain. A recent meta-analysis evaluated the diagnostic accuracy of UTI signs and symptoms in infants (3-24 mo) with fever (≥38°C),

Specimen Collection

A noncontaminated urine sample is fundamental. For infants and non–toilet-trained children, the most accurate method of collection is suprapubic bladder aspiration, however, it rarely is practical. Urethral catheterization or spontaneously voided clean midstream samples (usually obtained while disinfecting for catheterization or suprapubic bladder aspiration) are the most reliable alternatives. Perineal urine bag collection has a high rate of contamination and should be avoided for culture, but

Infants Younger Than 3 Months

All febrile neonates should be treated with intravenous antibiotics pending urine, blood, and cerebrospinal fluid culture results. For infants older than 1 month but younger than 3 months of age with suspected or confirmed UTI, intravenous antibiotics are recommended after appropriate cultures (blood, urine, ± cerebrospinal fluid). There have been no large prospective studies of outpatient management in this age group.27

Pyelonephritis: Infants Older Than 3 Months and Children

A 2007 Cochrane Review concluded that 10 to 14 days of oral treatment with

UTI Recurrence

Recurrent UTIs develop in approximately 75% of children whose first infection occurs before the age of 1 year, and in about 40% of girls and 30% of boys presenting after this age.37 Most studies of features predicting recurrence have important limitations.37 Risk factors identified include dilating VUR, family history of UTI, infrequent voiding, and inadequate fluid ingestion. Strategies that may help prevent recurrence include management of voiding dysfunction and increased fluid intake. The

Long-Term Outcome

Approximately 70% of infants and children with their first febrile UTI have pyelonephritis39, 40 and renal scars may follow in 15% to 30%.33, 41 With timely appropriate therapy most infants and children recover promptly without major long-term sequelae, but a small number are at risk for significant morbidity, progressive renal damage, and renal insufficiency. Included are those with urologic abnormalities, dysplasia, and recurrent pyelonephritis.37

Covert Bactiuria

Covert bactiuria (asymptomatic colonization of the urinary tract) is often an incidental finding during screening or follow-up evaluation after treatment of symptomatic UTI. If it is ascertained that the infant or child is truly symptom free, has a normal physical examination, normal voiding pattern, no impairment of renal function, and no anomalies on renal imaging, antibiotic therapy should be avoided.32 E coli strains causing asymptomatic bactiuria have evolved to persist for months to years

VUR and Reflux Nephropathy

VUR is a frequent pediatric urologic disorder affecting 1% to 2% of otherwise normal children.42 VUR is believed to predispose to UTI, and the two are linked with renal scarring. In 1960, Hodson and Edwards43 associated VUR with chronic pyelonephritis, which subsequently came to be known as reflux nephropathy.44 After acute pyelonephritis, renal scarring visible on intravenous urography takes about 1 to 2 years to develop, but is seen much earlier on DMSA.45, 46 The International Reflux Study

Conclusions

The recent knowledge about UTI and VUR, and controversies regarding the extent of their role in renal scarring, has generated much interest among clinicians as well as researchers. The consequences of delayed versus early treatment of acute febrile UTI and the appropriateness of medical versus surgical versus no intervention for various grades of VUR will continue to be debated until more prospective, randomized, and preferably blinded and placebo-controlled studies are performed to confirm or

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    Dr. Mattoo is supported by the National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases.

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