Urinary tract infections in children: why they occur and how to prevent them.

Urinary tract infections (UTIs) usually occur as a consequence of colonization of the periurethral area by a virulent organism that subsequently gains access to the bladder. During the first few months of life, uncircumcised male infants are at increased risk for UTIs, but thereafter UTIs predominate in females. An important risk factor for UTIs in girls is antibiotic therapy, which disrupts the normal periurethral flora and fosters the growth of uropathogenic bacteria. Another risk factor is voiding dysfunction. Currently, the most effective intervention for preventing recurrent UTIs in children is the identification and treatment of voiding dysfunction. Imaging evaluation of the urinary tract following a UTI should be individualized, based on the child's clinical presentation and on clinical judgment. Both bladder and upper urinary tract imaging with ultrasonography and a voiding cystourethrogram should be obtained in an infant or child with acute pyelonephritis. Imaging studies may not be required, however, in older children with cystitis who respond promptly to treatment.