Urinary tract infection in children

What is a urinary tract infection?

A urinary tract infection is inflammation of the urinary tract caused by bacteria. Most often E. coli, a bacterium that lives in the bowel, travels up the urethra into the bladder and sometimes reaches the kidney.

• Bladder infection (cystitis). Cystitis usually does not cause fever.
• Kidney infection (pyelonephritis). It usually causes fever and is more serious.

In the first year it is more common in boys, especially uncircumcised boys; after one year of age it is more common in girls.

Signs by age

In infants the signs are often nonspecific:

• fever without a clear cause (often the only sign),
• irritability, poor feeding, vomiting,
• poor weight gain, prolonged jaundice (in a newborn),
• foul-smelling urine.

In older children:

• burning and pain when urinating,
• frequent and urgent urination, new wetting,
• pain in the lower abdomen,
• cloudy, foul-smelling, sometimes bloody urine,
• fever, flank or back pain (in kidney infection).

Diagnosis: a correct urine sample

The diagnosis is made with a urinalysis and urine culture. How reliable the result is depends on how the sample is collected:

• In toilet-trained children: a midstream sample after washing the genitals.
• In children still in diapers: a catheter sample (or, rarely, suprapubic aspiration) for urinalysis and culture. The “clean catch” method is acceptable for a first screening test.
• A urine bag should not be used to collect a sample for culture. It is quickly contaminated by skin bacteria and a positive result is often false. A bag sample is useful only when it is completely negative, which makes infection unlikely.
• The sample is collected before the first antibiotic dose.

More: urinalysis and culture.

Treatment

Treatment should not be delayed: starting antibiotics later than 48–72 hours after the fever begins increases the risk of kidney scarring.

• Cystitis without fever: oral antibiotic, usually for 3–5 days.
• Infection with fever: a 4–7 day course of antibiotics, by mouth or intravenously. Babies younger than 2 months, children who are very unwell and those who cannot keep down oral medicine are given intravenous antibiotics, usually in the hospital.
• The antibiotic is changed according to the culture result when needed.
• Plenty of fluids, and medicines for fever and pain suited to age and weight.

Which children need further tests?

• After an infection with fever: kidney and bladder ultrasound. In infants and very unwell children it is done within 24 hours; in children treated at home it can be scheduled later.
• VCUG (voiding cystourethrogram) to check for reflux is not done during the infection and is selective. It is considered after a first febrile infection before 12 months of age, with recurrent febrile infections, an abnormal ultrasound or DMSA, or an atypical infection at any age. After a typical first infection with a normal ultrasound, waiting to see whether a second infection occurs is also an option.
• If kidney scarring is suspected: DMSA at least 6 months after the infection.

Preventing recurrence

• in toilet-trained children with febrile or recurrent infections, checking and treating bladder and bowel dysfunction, including constipation,
• enough water through the day and a toilet visit every 2–3 hours,
• in girls, wiping from front to back and avoiding bubble baths,
• in boys with recurrent infections and phimosis, steroid cream for the foreskin lowers recurrence; circumcision is considered when there is also reflux or another urinary tract problem,
• low-dose antibiotic prophylaxis for children at risk of recurrent infection (for example, with reflux or a dilated ureter in the first year of life), at the doctor’s decision.