Chapter 104: Urinary Tract Infections in Childhood

INTRODUCTION

Urinary tract infections (UTIs) are a common and important clinical problem in childhood and may lead to systemic illness and renal injury in the short term; with repeated infections, renal scarring, hypertension, and end-stage renal dysfunction that may develop.

The overall prevalence of UTI is estimated at 5% in febrile infants but varies widely by race and gender.^1,2 The highest prevalence rates of childhood UTI occur in uncircumcised male infants under 3 months of age (prevalence ~20%), and among females (prevalence ~8%). Circumcised older male children have the lowest prevalence of UTI (~1%) (Table 104-1).

PATHOGENESIS

Most UTIs beyond the newborn period represent an ascending infection. Colonization of the periurethral area by uropathogenic enteric organisms is the first step. The most common bacterial species is Escherichia coli, which accounts for about 80% of UTIs in children. Other bacteria include both gram-negative species (Klebsiella, Proteus, Enterobacter, and Citrobacter) and gram-positive species (Staphylococcus saprophyticus, Enterococcus, and rarely, Staphylococcus aureus). Attachment of bacteria to uroepithelial cells is an active process mediated by specific bacterial adhesions and specific receptor sites on the epithelial cells. This process allows bacteria to ascend into the kidney, even in children without vesicoureteral reflux (VUR). In the kidney, the bacterial inoculum can produce an infection with an intense inflammatory response that may ultimately lead to renal scarring.

Many host factors influence the predisposition that children may have to UTI, including familial predisposition, genitourinary anatomy and function, instrumentation, and sexual activity as well as periurethral flora. Determining risk factors in a child presenting with UTI is important in preventing further recurrences.

First-degree relatives of children with UTIs are more likely to have UTIs,³ and adherence of bacteria may, at least in part, be genetically determined.

Uncircumcised febrile male infants have a four- to tenfold higher prevalence of UTIs than circumcised males do.⁴ Although uncircumcised males are at increased risk for the development of a UTI, it is important to point out that UTIs do not develop in most uncircumcised boys.⁵ It is estimated that 195 circumcisions would be needed to prevent one hospital admission for UTI in the first year of life.⁴

Bladder and bowel dysfunction (BBD) refers to a functional disorder of unknown etiology characterized ...