CLINICAL PRESENTATIONS: URINARY TRACT INFECTION
Infection is the most common abnormality of the urinary system in children. The urinary tract is the second most common site of bacterial infections in children, after the respiratory tract. Although most urinary tract infections are relatively minor and respond promptly to appropriate treatment, chronic or recurrent infections can lead to severe, even life-threatening, complications such as hypertension and end-stage renal disease. Of urinary tract infections, those of the kidneys carry the greatest risk of clinically significant sequelae.
Urinary tract infections can involve the renal parenchyma, collecting system, bladder (cystitis), or urethra (urethritis). The commonly utilized term pyelonephritis indicates infection or inflammation of both the renal parenchyma and the pelvicaliceal system. Additional categories of kidney infections include diffuse pyelonephritis, focal pyelonephritis, renal abscess, pyonephrosis, perirenal abscess, and retroperitoneal abscess. Unless complicated by pyelonephritis, infectious cystitis is rarely associated with long-term sequelae.
Screening studies have demonstrated bacteriuria in 1% to 1.4% of all neonates.1–3 At this age, urinary tract infections are more common in males than in females. Uncircumcised infant boys are 8 to 10 times more likely to have a symptomatic urinary tract infection than circumcised boys.4 In preschool- and school-age children, bacteriuria is more prevalent in girls.5,6 The female-to-male ratio of urinary tract infection is 0.4:1 in the neonatal period, 1.5:1 at the age of 1 to 6 months, 4:1 at 6 to 12 months, 10:1 at 1 to 3 years, 9:1 at 3 to 11 years, and 2:1 at 11 to 16 years.7 Once treated, infants with symptomatic urinary tract infection have about a 25% risk for recurrent infection, usually within the first 3 months. In older girls, the risk for recurrence within 18 months is as high as 40% to 60%; this elevated risk persists into adulthood.5
The clinical manifestations of urinary tract infections tend to vary with patient age. In neonates, nonspecific systemic symptoms are common; bacteremia develops in 30% to 40%, and progression to life-threatening sepsis can occur. Urinary tract infections in infants beyond the neonatal period also frequently result in nonspecific systemic symptoms such as fever and abdominal pain. However, sepsis is much less frequent at this age than in neonates; bacteremia occurs in less than 20% of these children.
Dysuria is common in preschool- and school-age children with urinary tract infection. Other potential clinical manifestations include abdominal pain, flank pain, enuresis, and fever. Systemic symptoms are typically absent or less severe in this age group than in infants. Although the clinical presentation frequently points toward urinary tract involvement, a specific diagnosis is not always possible on clinical grounds alone. There are multiple potential causes of dysuria, including vaginitis, urethritis, and cystitis. Urine bacteria counts may be relatively low despite the presence of a bacterial urinary tract infection.
Teenagers with urinary tract infection tend to have a more straightforward clinical ...