Urinary Tract Infections in Children

UTI is defined as the presence of pathogenic micro-organisms in the genitourinary tract with accompanying symptoms. It is a common bacterial infection causing illness in infants and children. It is difficult to recognise because the symptoms and signs are non-specific, particularly in children under 3 [1]. Collecting urine and interpreting results is not easy in this age group, so it is not always possible to confirm the diagnosis.

Up to 7% of girls and 2% of boys will have a symptomatic, culture confirmed urinary tract infection (UTI) by the age of six. The prevalence of UTI in febrile infants is approximately 7% [2].

A systematic review in 2010 [3] found that 15% of children had evidence of renal scarring on a follow up DMSA scan after initial episode of UTI.

Historically, management after the acute infection has involved imaging, prophylaxis and prolonged follow up. This was costly, unpleasant for children, and had a limited evidence base. The current NICE guidelines [1] aim to achieve a more consistent clinical practice, based on accurate diagnosis and effective management.

Learning bite

Routine imaging of all children with a first time UTI is no longer carried out

It may be difficult to recognise UTI in children because the presenting symptoms and signs are non-specific, particularly in infants and children younger than 3 years. The table is the NICE guide to the symptoms and signs with which infants and children present [1].

Table 1: Presenting symptoms and signs in infants and children with UTI

Age group		Symptoms and signs
Infants younger than 3 months		Fever Vomiting Lethargy Irritability	Poor feeding Failure to thrive	Abdominal pain Jaundice Haematuria Offensive urine
Infants and children, 3 months or older	Preverbal	Fever	Abdominal pain Loin tenderness Vomiting Poor feeding	Lethargy Irritability Haematuria Offensive urine Failure to thrive
	Verbal	Frequency Dysuria	Dysfunctional voiding Changes to continence Abdominal pain Loin tenderness	Fever Malaise Vomiting Haematuria Offensive urine Cloudy urine

Urine testing who needs it?

The following children need a urine sample tested [1,4]:

• Infants less than 3 months old with a fever
• Infants and children presenting with unexplained fever of >38 C
• Infants and children with an alternative site of infection should not have a urine sample tested. When infants and children with an alternative site of infection remain unwell, urine testing should be considered.
• Children with signs and symptoms of UTI

Pitfall:

1-10% of young children will have asymptomatic bacteruria (bacteria in their urine when they are well). So, finding evidence of a UTI (e.g. positive urine dipstick) in a sick child does not exclude another source of serious infection (e.g. meningitis).

Urinary Collection Techniques

A clean catch sample is the preferred technique for urine collection, however this may be very time consuming in young children [1].

One way of achieving this in the ED for a child in nappies is to remove the nappy, place several inco-pads over the parents lap. Clean the perineum with water. The parent waits with the child on their lap, or on the bed, holding a sterile pot / bowl for the child to pass urine.

Using gauze soaked with cold water to rub the suprapubic area has been shown to increase the rate of voiding and clean catch urine collection. [5]

Failing this, urine collection pads may be used. Do not use gauze, cotton wool or other ad hoc techniques, as this greatly increases the risk of contamination.

When not possible or practical to use non-invasive methods, a catheter sample or suprapubic aspiration can be used. Prior to aspiration, ultrasound should be used to demonstrate urine in the bladder. [1]

Urine dipstick

Urine testing strategies for Infants less than 3 months

All infants younger than 3 months with suspected UTI should be referred to paediatric specialist care and a urine sample should be sent for urgent microscopy and culture. These infants should be managed in accordance with the recommendations for this age group in Fever in under 5s [4]. Do not use a urine dipstick to guide management of possible UTI in this age group.

Urine-testing strategies for infants and children 3 months or older but younger than 3 years

Use dipstick testing for infants and children 3 months or older but younger than 3 years with suspected UTI [1].

	Leukocyte Positive	Leukocyte Negative
Nitrite Positive	Start antibiotic, send urine culture	Start antibiotic, send urine culture
Nitrite Negative	Start antibiotic, send urine culture	No antibiotic. Do not send urine culture (unless meets additional criteria)

Urine-testing strategies for children 3 years or older

Use dipstick testing for children over 3 years with suspected UTI [1].

	Leukocyte Positive	Leukocyte Negative
Nitrite Positive	Treat as UTI Send urine culture if high/intermediate risk of serious illness and/or history of previous UTI	Treat as UTI if fresh sample Send urine culture
Nitrite Negative	Only treat as UTI if good clinical evidence of such. Send urine culture NB May represent infection outside of urinary tract.	No UTI Do not send urine culture

When to send urine for culture

(In all ages) NICE recommends that urine culture is indicated in the following cases [1]:

1. Infants and children who are suspected to have acute pyelonephritis/upper urinary tract infection
2. Infants and children with a high to intermediate risk of serious illness
3. Infants under 3months
4. Infants and children with a positive result for leukocyte esterase or nitrite
5. Infants and children with recurrent UTI
6. Infants and children with an infection that does not respond to treatment within 2448hours, if no sample has already been sent
7. When clinical symptoms and dipstick tests do not correlate.

If urine samples can be sent in a sterile pot, but if they will not be cultured within 4 hours then they should be refrigerated or preserved in boric acid [1]. Ensure you are aware of your local microbiology guidance to reduce the risk of samples being wasted.

Treatment is determined by age, upper vs lower UTI and clinical condition.

Infants less than 3 months

NICE recommends that children under 3 months should be referred to paediatrics for IV antibiotics. Initial antibiotic therapy for infants under 3 months with fever is a third generation cephalosporin together with an antibiotic with listeria coverage (e.g. ceftriaxone and amoxicillin) [4, 6].

Infants and children older than 3 months

With bacteuria (demonstrated by a positive leukocytres/nitrites on dipstick), and either;
Fever >38 C or
Loin pain/tenderness
= Treat as pyelonephritis/upper UTI [1]

With bacteriuria(demonstrated by a positive leukocytres/nitrites on dipstick) with;
No systemic symptoms or signs
= Treat as cystitis/lower UTI [1]

Learning Point:

Do not use CRP to differentiate between pyelonephritis and cystitis

Antibiotic Choice

Consider allergies, recent antibiotic use, previous urine MC&S results and local microbiology guidance when prescribing.

Pyelonephritis if; [6]

• Sepsis/severely unwell
• Vomiting/unable to take oral medications

IV antibiotics e.g. Cefuroxime, ceftriaxone, co-amoxiclav, gentamicin

Pyelonephritis otherwise; [6]

Oral antibiotic for 7-10 days e.g. cefalexin, co-amoxiclav

Cystitis[7]

Oral antibiotic for 3 days e.g. trimethoprim, nitrofurantoin

Imaging is typically indicated for one of two reasons. Firstly, atypical infection may suggest obstruction that requires urgent intervention. Secondly, UTIs may arise from structural abnormalities such as vesicoureteric reflux (VUR), or cause renal scarring leading to renal dysfunction. [8]

Ultrasound is the first line imaging of choice. It is relatively easily accessible, non-ionising, non-invasive and can detect most anatomical abnormalities and hydronephrosis suggestive of obstruction or VUR.

Dimercaptosuccinic Acid (DMSA) scans are a nuclear isotope uptake scan. Reduced renal uptake can represent acute infection or longterm scarring.

Voiding Cystourethrograms (VCUG) use fluoroscopy where contrast is injected into the bladder via a catheter. It is the gold standard for assessing bladder function and ureteric reflux, but is resource and radiation intensive.

The full NICE guidance for imaging can be found here, however it is a key point for EM clinicians is to recognise those children that will require ultrasound imaging during the acute infection, thus requiring admission. These are [1]:

Any infant/child with an atypical infection, suggested by:

• Seriously ill
• Poor urine flow
• Abdominal or bladder mass
• Raised creatinine
• Sepsis
• Failure to respond to treatment with suitable antibiotics within 48hours
• Infection with non-E. coli organisms

Any infant <6 months old with recurrent UTI

• 2 or more episodes of UTI with acute pyelonephritis/upper urinary tract infection
• 1 episode of UTI with acute pyelonephritis/upper urinary tract infection plus one or more episode of UTI with cystitis/lower urinary tract infection
• 3 or more episodes of UTI with cystitis/lower urinary tract infection

If none of these apply, but the child is;

• Under 6 months old or
• Has an atypical UTI or
• Has recurrent UTIs

Then they are likely to need follow up outpatient imaging. If discharging these patients from ED, it is important to ensure they have appropriate follow up arranged.

NICE recommend good hygiene practices and avoiding dehydration to reduce the risk of UTIs [9].

Antibiotic prophylaxis in children used to be commonplace following a UTI. However, there is no strong evidence to support this routinely, and it carries increased risks of antimicrobial resistance and has an impact of patients quality of life [9].

NICE now recommend that antibiotic prophylaxis only be started under specialist guidance, and when other management options have been unsuccessful [9].

1. National Institute for Health and Clinical Excellence. Clinical Guideline 54. Urinary tract infection in under 16s: diagnosis and management. 2007 (Updated 2018); London: NICE.
2. Alper BS, Curry SH. Urinary tract infection in children. American Family Physician. 2005; 72(12): 2483-8.
3. Shaikh N, Ewing AL, Bhatnagar S, Hoberman A. Risk of renal scarring in children with a first urinary tract infection: a systematic review. Paediatrics 2010 Dec; 126 (6): 1084-91
4. National Institute for Health and Clinical Excellence. NICE Guideline 143. Fever in under 5s: assessment and initial management. 2019; London: NICE.
5. Kaufman et al., Faster clean catch urine collection (Quick-Wee method) from infants: randomised controlled trial. BMJ. 2017; 357;j1341
6. National Institute for Health and Clinical Excellence. NICE guideline 111. Pyelonephritis (acute): antimicrobial prescribing. 2018; London: NICE.
7. National Institute for Health and Clinical Excellence. [NICE guideline 109] Urinary tract infection (lower): antimicrobial prescribing. 2018; London: NICE
8. Kaufman, J., Temple-Smith, M., & Sanci, L. Urinary tract infections in children: an overview of diagnosis and management. BMJ Paediatrics Open, 3(1), e000487, 2019.
9. National Institute for Health and Clinical Excellence. Clinical guideline 112. Urinary tract infection (recurrent): antimicrobial prescribing. 2018; London: NICE.