Urinary Tract Infection in Children

Authored by , Reviewed by Dr Laurence Knott | Last edited | Meets Patient’s editorial guidelines

This article is for Medical Professionals

Professional Reference articles are designed for health professionals to use. They are written by UK doctors and based on research evidence, UK and European Guidelines. You may find the Urine Infection in Children article more useful, or one of our other health articles.

Treatment of almost all medical conditions has been affected by the COVID-19 pandemic. NICE has issued rapid update guidelines in relation to many of these. This guidance is changing frequently. Please visit https://www.nice.org.uk/covid-19 to see if there is temporary guidance issued by NICE in relation to the management of this condition, which may vary from the information given below.

The diagnosis of urinary tract infection (UTI) in young children is important as it may be a marker for urinary tract abnormalities. UTI is the most common bacterial infection in children under 2 years old. UTI presents atypically in neonates and may be associated with life-threatening sepsis.

Lower urinary tract infection: a UTI involving the bladder and urethra.

Upper urinary tract infection: a UTI involving the renal pelvis and/or kidney (pyelonephritis). The National Institute for Health and Care Excellence (NICE) advises that clinically an upper UTI should be assumed if there is bacteriuria and fever of 38°C or higher, or if there is a fever lower than 38°C with loin pain/tenderness and bacteriuria.

Undifferentiated urinary tract infection: a UTI where it is not possible to distinguish between the two conditions above.

Recurrent urinary tract infection: a child has had two episodes of upper UTI, three or more episodes of lower UTI, or one episode of upper UTI and one or two episodes of lower UTI. See also the article on Recurrent Urinary Tract Infection.

Asymptomatic bacteriuria: the presence of bacteria in an appropriately collected sample of urine, without the presence of symptoms.

Atypical urinary tract infection: NICE defines this as a UTI where there are any of the following features:

  • Seriously ill/septicaemia.
  • Poor urine flow.
  • Presence of an abdominal or bladder mass.
  • Lack of response within 48 hours to treatment with suitable antibiotics.
  • An unusual causative organism (ie not Escherichia coli).
  • An increased serum creatinine level.

This is relevant to guidelines on the need for further investigation (see later).

UTI may be classified by:

    • Site: upper or lower as above
    • Severity: simple or severe UTI, where severe UTI would include a fever of 39°C or more, the feeling of being ill, persistent vomiting and moderate or severe dehydration.
    • Episode: first or recurrent. Recurrent UTI may be subclassified into three groups:
      • Unresolved infection: subtherapeutic level of antimicrobial, non-compliance with treatment, malabsorption, resistant pathogens.
      • Bacterial persistence: may be due to a nidus for persistent infection in the urinary tract. Surgical correction or medical treatment for urinary dysfunction may be needed.
      • Re-infection: each episode is a new infection acquired from periurethral, perineal or rectal flora.
  • Symptoms: asymptomatic or symptomatic bacteriuria.
  • Complicating factors: uncomplicated or complicated UTI.
  • Febrile UTI is the most common serious bacterial infection in childhood[3] .
  • Up to 11% of girls and 7% of boys will have had a urinary tract infection (UTI) by the age of 16 years, and recurrence of infection is common.
  • Vesicoureteric reflux (VUR) is identified in up to 40% of children being investigated for a first UTI, and is a risk factor for, but weak predictor of, renal parenchymal defects.
  • Boys have a higher incidence of UTI up to the age of 6 months, after which it is more common in girls. Girls also have a higher incidence of recurrent UTI.
  • 3% of girls and 1% of boys will have an upper UTI by the age of 7.

Risk factors

  • Any condition that leads to urinary stasis (renal calculi, obstructive uropathy, vesicoureteric reflux (VUR) - or family history of, voiding disorders) or poor urine flow - eg, phimosis.
  • Dysfunctional elimination syndrome.
  • Sexual abuse.
  • History suggestive of, or confirmed previous, UTI.
  • Constipation.
  • Spinal abnormalities.

There is no associated risk factor in the majority of cases.

  • Infants younger than 3 months: urine tract infection symptoms in neonates differ to those in older children. Fever, vomiting, lethargy and irritability are common. Poor feeding and failure to thrive may occur. Abdominal pain, jaundice, haematuria and offensive urine are less common. Neonates are more likely to develop urosepsis and infections in neonates are less likely to be due to E. coli.
  • Infants and preverbal children aged 3 months or older: fever is common. There may also be abdominal pain, loin tenderness, vomiting and poor feeding. Lethargy, irritability, haematuria, offensive urine and failure to thrive are less common. In verbal children, frequency and dysuria are the most common presenting symptoms. In preverbal children, presentation is most often a fever with no apparent cause.
  • Children aged over 3 years: usual presentation is with specific symptoms such as frequency, dysuria and suprapubic, abdominal or lumbar pain. Dysfunctional voiding and changes to continence may occur. Other less common symptoms include fever, malaise, vomiting, haematuria, offensive urine and cloudy urine.

Symptoms or signs that indicate a high risk of serious illness in children under the age of 5 years include[2] :

  • Temperature of 38°C or higher in an infant younger than 3 months of age.
  • Pale/mottled/ashen/blue skin, lips, or tongue.
  • No response to social cues.
  • Appearing ill to a healthcare professional.
  • Not waking, or if roused not staying awake.
  • Weak, high-pitched or continuous cry.
  • Grunting.
  • Respiratory rate greater than 60 breaths per minute.
  • Moderate or severe chest indrawing.
  • Reduced skin turgor.
  • Bulging fontanelle.

The temperature of the child should always be taken and recorded. The following should also be examined:

  • Throat and cervical lymph nodes.
  • Abdomen - to look for constipation, tender or palpable kidney.
  • Back - to look for stigmata of spina bifida or sacral agenesis.
  • Genitalia - to look for phimosis, labial adhesions, vulvitis or epididymo-orchitis.

NICE advises that[1] :

  • A diagnosis of acute pyelonephritis/upper UTI should be assumed in:
    • Infants and children who have bacteriuria and a fever of 38°C or more.
    • Infants and children presenting with fever less than 38°C associated with loin pain/tenderness and bacteriuria.
  • A diagnosis of cystitis/lower UTI should be assumed in all other infants and children who have bacteriuria but no systemic symptoms or signs.

Clinical diagnosis of UTI is unreliable, so many children with fever or symptoms of UTI need a urine sample to exclude or make the diagnosis. Urine samples should be collected before starting antibiotics, but therapy should not be delayed in the septic child[5] .

Collecting the urine sample

Ideally, a urine sample should always be taken prior to starting any antibiotics. This can be obtained in various ways, depending on the age of the child and also the clinical presentation of the child.

A clean catch urine sample is the method for urine collection recommended by NICE. The child is placed in the lap of a parent or member of the nursing staff, who holds a sterile foil bowl underneath the infant's genitalia. The infant is offered oral fluids and urine collection is awaited. Although this is time-consuming, there seems to be a good correlation between the results of urine culture obtained by this method and suprapubic aspiration (SPA), with a false positive rate of only 5% and false negative rate of 12%[6] . This technique is obviously much easier in toilet-trained children.

If a clean catch urine sample is not possible:

  • A collection bag attached to cleaned genitalia can be used. However, if the genitalia are not cleaned and culture is delayed, there can be a high incidence of false positive results (85-99%)[3] .
  • Use other non-invasive methods such as urine collection pads but do not use cotton wool balls, gauze or sanitary towels.
  • Alternatively, a catheter sample or SPA of urine may be collected where sufficient experience and resources exist. The decreased contamination rate offered by either of these methods can offset the disadvantage of being an invasive procedure. They may be most appropriate in:
    • Pre-toilet-trained children with fever and no focus, or where UTI is considered likely.
    • Children with a history of UTI/VUR/on UTI prophylaxis/having renal tract anomalies.
    • Very sick children.

If the sample needs to be cultured but cannot be cultured within four hours of collection, either refrigerate or preserve it with boric acid immediately.

Dipstick testing

Nitrites are not a very sensitive dipstick test in infants. This is because not all urinary pathogens reduce nitrate to nitrite. However, false negatives are rare. Dipstick testing is appropriate in children over the age of 3 months.

If there is a positive dipstick test then the sample should be sent for urine culture. If both leukocyte esterase and nitrite are negative: do not start antibiotic treatment; do not send a urine sample for microscopy and culture. If leukocyte esterase or nitrite, or both are positive: start antibiotic treatment and send a urine sample for culture.

Urine testing

  • Aged <3 months: if UTI is suspected clinically, refer to a paediatrician. A urine sample is sent for urgent microscopy and culture.
  • Aged >3 months but <3 years: send a sample for urgent microscopy and culture. Await the result before starting treatment, unless there are specific urinary symptoms or the child is systemically unwell.
  • Aged >3 years: use dipstick test to diagnose UTI:
    • If leukocyte esterase and nitrite are positive: start antibiotic treatment for UTI and, if the child has a high or intermediate risk of serious illness or a history of infection, send urine sample for culture.
    • If leukocyte esterase is negative and nitrite is positive: start antibiotic treatment if a fresh sample was tested and send urine sample for culture.
    • If leukocyte esterase is positive and nitrite is negative: send urine sample for microscopy and culture. Only start antibiotic treatment for UTI if there is good clinical evidence of such infection.
    • If leukocyte esterase and nitrite are negative: do not start treatment for UTI; explore other causes of illness.


Imaging is usually arranged by secondary care.

  • Ultrasound[7] :
    • Can accurately assess renal size and outline and identify most congenital abnormalities, renal calculi and hydronephrosis or hydroureter, indicating the presence of obstruction or severe reflux.
    • It is less effective in detecting mild or moderate VUR in children with UTIs.
  • Micturating cystography[7] :
    • Is the gold standard investigation for reflux and is the only imaging technique that provides information about the urethra.
    • Should be performed by a skilled radiologist with experience in acquiring and interpreting the images.
    • The disadvantage of micturating cystography is its invasiveness, as it requires catheterisation.
  • Dimercaptosuccinic acid scintigraphy (DMSA)[7] :
    • Is the gold standard for detecting renal parenchymal defects.
    • Study renal function using a radio-pharmaceutical such as technetium99m.
    • The isotope is concentrated in the proximal renal tubules; its distribution correlates with functioning renal tissue.

An ultrasound of the urinary tract should be arranged:

  • During the acute infection in all children with atypical infection, indicated by:
    • Poor urine flow.
    • Abdominal or bladder mass.
    • Raised creatinine.
    • Sepsis.
    • Failure to respond to treatment with suitable antibiotics within 48 hours.
    • Infection with non-E. coli organisms.
  • During the acute infection in children aged under 6 months with recurrent UTI.
  • Within six weeks for children aged 6 months and over with recurrent UTI.
  • Within six weeks, for all children younger than 6 months of age with first-time UTI that responds to treatment.

Infants and children with abnormal imaging results should be assessed by a paediatric specialist.

DMSA should be arranged by paediatric specialists to detect renal parenchymal defects and should be carried out within 4-6 months following the acute infection in:

  • All children aged under 3 years with atypical or recurrent UTI.
  • All children aged 3 years or over with recurrent UTI.

General principles

  • The aims of urinary tract infection treatment are to:
    • Eliminate urinary tract infection symptoms and eradicate bacteriuria.
    • Prevent renal scarring.
    • Prevent recurrent UTIs.
    • Correct any associated urological lesions.
  • Children with a high risk of serious illness and/or aged younger than 3 months should be referred immediately to secondary care. This should be assessed in accordance with NICE guidance on feverish illness in children - see Further Reading, below.
  • Do not delay treatment if the sample cannot be obtained and the infant or child is at high risk of serious illness.

Carefully assess the degree of toxicity, dehydration and ability to maintain oral fluid intake. Encourage fluids, avoid or correct constipation and encourage full voiding.

  • If the child has been assessed at high risk of serious illness, refer urgently to secondary care.
  • If UTI is suspected in children aged under 3 months, refer urgently to a paediatric specialist for treatment with parenteral antibiotics, and send a urine sample for urgent microscopy and culture.

For children 3 months or older with acute pyelonephritis/upper UTI:

  • Consider referral to a paediatric specialist.
  • Use clinical judgement to determine whether this is necessary.
  • Start oral antibiotic treatment with cefalexin, or co-amoxiclav (only if culture results are available and susceptible).
  • If culture results show that the causative organism is resistant to the initially prescribed antibiotic, switch to an alternative. Infants and children who are already receiving prophylactic antibiotics, should be treated with an alternative antibiotic.

For children 3 months or older with cystitis/lower UTI:

  • Start oral antibiotic treatment - first-line options include trimethoprim (if there is low risk of resistance), or nitrofurantoin (if eGFR ≥45 ml/minute).
  • Second-line options include nitrofurantoin (if eGFR ≥45 ml/minute) if it has not been used as a first-line option, amoxicillin (only if culture results available and susceptible), or cefalexin.
  • If culture results show that the causative organism is resistant to the initially prescribed antibiotic, switch to an alternative.
  • Infants and children who are already receiving prophylactic antibiotics, should be treated with an alternative antibiotic.

If dysfunctional elimination syndromes and/or constipation are suspected, these should be addressed.

  • For children with suspected voiding dysfunction and/or urine withholding, regular bladder-emptying during the day (every 90-120 minutes) should be advised.
  • Stool softener may be prescribed if there is constipation.

Although it is recommended that children aged 3 months and over with cystitis or infection of the lower urinary tract should be treated with three days of oral antibiotics according to local guidance, there is some evidence that outcomes of short courses (1-3 days) are inferior to those of 7- to 14-day courses[3] . In addition, a Cochrane review has found that 10-day antibiotic treatment is more likely to eliminate bacteria from the urine than single-dose treatments[9] .

The Cochrane review also concluded there were insufficient data to advise about the best choice of antibiotic, which should be therefore be determined by local guidelines. The antibiotic may need to be adjusted according to the MSU results. Currently, Public Health England (PHE) guidelines advise that in a lower UTI, trimethoprim or nitrofurantoin should be first-line choices[10] .

Most children recover quickly and completely with antibiotic treatment. Recurrence of UTI is more likely in:

  • Younger children, ie aged less than 6 months.
  • Girls compared with boys.
  • VUR grade 3-5, compared with reflux grade 1-2, or no reflux.
  • Dysfunctional voiding syndrome; this is an abnormality of emptying, due either to a small-capacity, unstable bladder or a large-capacity, poorly emptying bladder.

Risk of recurrence is estimated to be 75% for infants under 1 year of age and 40% (for girls)/30% (for boys) aged over 1 year.

VUR resolves spontaneously in most children.

Potential complications of urinary tract infections in children include:

  • Renal scarring (more likely in children with VUR). Prompt treatment of UTIs reduces renal scarring[11] .
  • Hypertension (associated with severe renal scarring).
  • Possible link with increased risk of bacteriuria, pre-eclampsia and hypertension in pregnancy in later life.

Advice which may help prevent recurrence includes:

  • Management of voiding dysfunction.
  • Good hygiene.
  • Avoiding constipation.
  • Adequate fluid intake.
  • Avoidance of delayed voiding; ready access to clean toilets.

NICE recommends the following regarding prophylaxis:

  • Antibiotic prophylaxis should not be routinely recommended in infants and children following first-time UTI.
  • Antibiotic prophylaxis may be considered in infants and children with recurrent UTI[12] .
  • Asymptomatic bacteriuria in infants and children should not be treated with prophylactic antibiotics.

A Cochrane review concluded that no significant benefit was demonstrated for probiotics for preventing UTIs in adults and children compared with placebo or no treatment, but a benefit cannot be ruled out as the data were few, and derived from small studies with poor methodological reporting[13] .

Further reading and references

  1. Urinary tract infection in under 16s: diagnosis and management; NICE Clinical guideline (August 2007, updated October 2018)

  2. Urinary tract infection - children; NICE CKS, February 2019 (UK access only)

  3. EAU Paediatric Urology Guidelines. Edn. presented at the EAU Annual Congress Copenhagen; European Association of Urology, 2018 - updated 2021

  4. Larcombe J; Urinary tract infection in children: recurrent infections. BMJ Clin Evid. 2015 Jun 122015. pii: 0306.

  5. Kaufman J, Temple-Smith M, Sanci L; Urinary tract infections in children: an overview of diagnosis and management. BMJ Paediatr Open. 2019 Sep 243(1):e000487. doi: 10.1136/bmjpo-2019-000487. eCollection 2019.

  6. Roberts KB; Urinary tract infection: clinical practice guideline for the diagnosis and management of the initial UTI in febrile infants and children 2 to 24 months. Pediatrics. 2011 Sep128(3):595-610. doi: 10.1542/peds.2011-1330. Epub 2011 Aug 28.

  7. Davis A, Obi B, Ingram M; Investigating urinary tract infections in children. BMJ. 2013 Jan 30346:e8654. doi: 10.1136/bmj.e8654.

  8. Fever in under 5s: assessment and initial management; NICE Guidance (last updated November 2021)

  9. Fitzgerald A, Mori R, Lakhanpaul M, et al; Antibiotics for treating lower urinary tract infection in children. Cochrane Database Syst Rev. 2012 Aug 158:CD006857. doi: 10.1002/14651858.CD006857.pub2.

  10. Managing common infections: guidance for primary care; Public Health England, August 2020 - last updated June 2021

  11. Veauthier B, Miller MV; Urinary Tract Infections in Young Children and Infants: Common Questions and Answers. Am Fam Physician. 2020 Sep 1102(5):278-285.

  12. Urinary tract infection (recurrent): antimicrobial prescribing; NICE guideline (October 2018)

  13. Schwenger EM, Tejani AM, Loewen PS; Probiotics for preventing urinary tract infections in adults and children. Cochrane Database Syst Rev. 2015 Dec 2312:CD008772. doi: 10.1002/14651858.CD008772.pub2.