Pediatric Urinary Tract Infections

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Classification

A UTI is defined as colonization of a pathogen occurring anywhere along the urinary tract: kidney, ureter, bladder, and urethra. Traditionally, UTIs have been classified by the site of infection (ie, pyelonephritis [kidney], cystitis [bladder], urethra [urethritis]) and by severity (ie, complicated versus uncomplicated). A complicated UTI describes infections in urinary tracts with structural or functional abnormalities or the presence of foreign objects, such as an indwelling urethral

Epidemiology

The true incidence of pediatric UTI is difficult to determine because there are varying presentations that range from an absence of specific urinary complaints to fulminant urosepsis. Data from the Urologic Disease in America project, however, suggest that pediatric UTI constitutes a significant health care burden on the American public. The study revealed that infections of the urinary tract affect 2.4% to 2.8% of children every year and account for more than 1.1 million office visits

Uropathogens

Although UTI may be caused by any pathogen that colonizes the urinary tract (eg, fungi, parasites, and viruses), most causative agents are bacteria of enteric origin (Box 2). The causative agent varies based on age and associated comorbidities. E coli is the most frequent documented uropathogen. Among neonates, UTI secondary to group B streptococci is more common than in older populations [21]. In immunocompromised children and children with indwelling catheters, Candida may be isolated from

Pathogenesis

Bacterial clonal studies strongly support entry into the urinary tract by the fecal-perineal-urethral route with subsequent retrograde ascent into the bladder [10]. Because of differences in anatomy, girls are at a higher risk of UTI than boys beyond the first year of life. In girls, the moist periurethral and vaginal areas promote the growth of uropathogens. The shorter urethral length increases the chance for ascending infection into the urinary tract. Once the uropathogen reaches the

Risk factors

Although all individuals are susceptible to UTI, most remain infection free during childhood because of the aforementioned innate ability to resist uropathogen attachment. There are specific subpopulations with an increased susceptibility to UTI, however (Box 3).

Clinical presentation

Children who have UTI often do not necessarily present with the characteristic signs and symptoms seen in the adult population. The physical examination is also frequently of limited value because costovertebral angle and suprapubic tenderness are not reliable signs in the pediatric population. There are various clinical presentations for children with UTI based on age. Infants younger than 60 to 90 days may have vague and nonspecific symptoms of illness that are difficult to interpret, such as

Diagnosis

The definitive diagnosis of a UTI requires the isolation of at least one uropathogen from a urine culture [64], [65]. Urine, which should be obtained before the initiation of antimicrobial therapy, can be collected by various methods. The simplest and least traumatic method is via a bagged specimen, which involves attaching a plastic bag to the perineum. Clinicians, however, are discouraged from obtaining a urine specimen in this fashion because there is an unacceptably high false-positive rate

Diagnostic imaging studies

In the acute setting of a UTI, diagnostic imaging tests are generally not indicated unless the diagnosis of UTI is equivocal. Recently, Hoberman and colleagues [67] demonstrated that a renal bladder ultrasound and renal scan obtained within 72 hours of the febrile UTI in young children is of limited value. The authors argued that the use of ultrasound to identify a urinary tract malformation is minimal given the prevalence of prenatal ultrasonography in the United States. If, however, the signs

Management

Because treatment for a suspected UTI generally starts when the causative agent is identified, empiric treatment of UTI is based on the clinical status of the child, the predominant uropathogens for the patient's age group coupled with the antimicrobial sensitivities in the community, and patient compliance and ability for follow-up.

A generally healthy young child with a presumed uncomplicated UTI who is nontoxic, is taking in fluids, has reliable caretakers, and is able to follow-up on a daily

Complications

The interaction of the host, uropathogen, and environment is incompletely understood not only in the development of infections of the urinary tract but also the progression of pediatric UTI. As a result, it is difficult to determine whether an episode of cystitis will resolve without incident or result in more serious infection involving the kidney. A pediatric urology referral should be considered in children suspected of having serious sequelae of pyelonephritis, including renal abscess

Long-term consequences of pediatric urinary tract infection

Children with upper UTI (ie, pyelonephritis) are at risk for irreversible renal parenchymal damage evidenced by renal scarring. Renal scarring is noted in 10% to 30% of children after UTI [112], [113]. The most widely used method of detecting renal scarring is 99Tc-labeled dimercaptosuccinic acid scintigraphy scan [69]. Although the exact mechanisms responsible for renal scarring secondary to UTI are currently unclear [114], risk factors include underlying VUR or obstructive urinary tract

Summary

Infections of the urinary tract are among the most common infections in the pediatric population. If not treated promptly and appropriately, pediatric UTI may lead to significant acute morbidity and irreversible renal damage. Children, however, have a wide variety of clinical presentation, ranging from the asymptomatic presence of bacteria in the urine to potentially life-threatening infection of the kidney. A clinician's main goals are early diagnosis, appropriate antimicrobial therapy,

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