Urinary Tract Infection in Babies and Children: Signs That Are Often Subtle

Your 7-month-old has had a temperature of 39 °C since yesterday. No cold, no cough, no rash, he is drinking a little less and is grumpy. Nothing obvious, and yet the paediatrician asks for a urine test. This is a classic reflex: a urinary tract infection in a baby is one of the common causes of fever with no explanation, and it easily goes unnoticed because an infant cannot tell you it hurts when they pee.

Properly treated and in good time, it heals without any lasting effect. The point is precisely not to let it drag on, especially when it reaches the kidneys. Here are the signs to know by age, the tests, the treatment and the prevention habits.

What are the signs of a urinary tract infection at each age?

They change a lot between a baby and a child who can talk.

The MSD Manual sums it up: in a baby, fever may be the only symptom. And in a newborn, the infection can become serious quickly. That is why any fever before 3 months calls for immediate medical advice, as we explain in our guide to fever in babies.

In a toilet-trained child, a return of wetting accidents or of bedwetting can also be the first sign.

How does the doctor make the diagnosis?

In two steps, with two urine tests that do not serve the same purpose.

The urine dipstick is a quick test, done at the surgery or in the emergency department: a strip is dipped into the urine and the result is read within minutes. It looks for white blood cells and nitrites. According to French paediatric guidelines, it is reliable from about one month of age. If negative, it makes an infection very unlikely. If positive, it leads to the next step. Before 3 months, the dipstick is not enough: the full test is done straight away.

The urine culture (called ECBU in France) is the laboratory analysis. It confirms the infection, identifies the bacterium and tests which antibiotics work against it (the antibiogram). It must be collected before the antibiotic is started.

Collecting the urine, a delicate step

Everything depends on how clean the sample is. In an older child, the midstream urine is collected after a careful wash. In an infant, the adhesive bag is simple but often contaminated by the skin: a positive result obtained this way is false more than once in two. Paediatricians therefore often prefer a small catheter, done at the hospital or clinic, or a "catch" sample, collected at the moment the baby pees.

What treatment for a urinary tract infection in a child?

An antibiotic, chosen by the doctor, then adjusted according to the antibiogram. The dose is calculated by the doctor according to the child's weight. The regimen depends on the type:

• a cystitis (bladder) is treated by mouth, over a few days;
• a pyelonephritis (kidney) needs a longer treatment, often started by injection, then continued by mouth.

Hospital admission is recommended for a baby under 3 months, when the child looks very ill, is dehydrated, copes badly with the fever, or has a known abnormality of the urinary tract. In other cases, many children are treated at home, with close follow-up.

Finish the whole course, even if the fever drops within 24 or 48 hours. Offer drinks regularly. For fever and pain, paracetamol can be given, at the dose indicated by the doctor or pharmacist according to your child's weight. The NHS advises seeing the doctor again if the child is no better 48 hours after starting treatment.

Are tests needed afterwards?

Often an ultrasound of the kidneys and bladder after a first pyelonephritis, to check there is no malformation. Other tests, such as the cystography, which looks for reflux of urine from the bladder back towards the kidneys, are no longer routine after a first episode: experts debate it and decide case by case, especially if it recurs.

Recurrences are not rare: VIDAL Recos estimates them at about a third of cases. If fever comes back, tell the doctor about the previous episode: they will quickly repeat a dipstick.

How can urinary tract infections be prevented?

A few simple habits reduce the risk, especially in a child who has already had an infection:

• treat constipation: a full bowel hinders the emptying of the bladder and favours infections (see our article on constipation in babies);
• offer water regularly, especially in hot weather;
• don't hold on: pee about every 2 to 3 hours and empty the bladder completely, without rushing;
• wipe from front to back, and teach little girls this movement;
• change nappies promptly when soiled;
• avoid bubble baths and perfumed soaps on the private parts;
• prefer cotton underwear.

For a child in the middle of potty training, a potty or toilet seat reducer where they feel stable, feet resting, helps them relax and empty the bladder fully. At school, check that your child dares to ask to go to the toilet: some children hold on all morning.

For a little boy with repeated infections, the MSD Manual mentions circumcision among possible measures; this is a discussion to have with a paediatric urologist, not a routine preventive step.