Overview

Urinary Tract infections (UTIs) in children are common and usually carry low risk. UTIs are often non-specific and can not be diagnosed on symptoms alone. A clean specimen (urine) is required for the diagnosis of UTI. Any child who is unwell, and most children under 6 months, should be admitted for IV antibiotics. The risk for child to develop a UTI in general is ~5% (girls > boys). Of these ~25% will experience recurrence within one year. However, in the first year UTI are more common in boys, uncircumcised boys are 10times more likely to develop a UTI compared with circumscribed boys.

Aetiology and Risk Factors

Aetiology

Escherichia coli (75%)

Other

• Enterococcus faecalis (~10%)
• Proteus Klebseilla
• Enterobacter
• Citrobacter
• Staphylococcus saprophyticus
• Candida albican  (Fungal) – usually in immunocomprimised or following antibiotic use.

Pathophysiology

UTI susceptibility is determined by:

• Bacterial virulence
• Anatomical variances
  • Gender
  • Vesicourethral reflux
  • Circumcision
• Bowel of bladder dysfunction
• Host defences

Clinical Manifestation

Urinary tract infection in children are often non-specific and can not be diagnosed on symptoms alone.

Infants:

• Unwell
• Poor feeding
• Fever
• Sepsis

Older children can present with the classic:

• Dysuria
• Frequency
• Loin Pain

Diagnosis

If fever and feeling unwell is the sole presenting symptom, such as seen in <2yo, think of other differentials.

• Otitis media
• Gastroenteritis
• Upper respiratory tract infection

Urine should be collected if there is a unexaplined fever and/or symptoms suggestive of UTI.

Method to obtain urine sample include:

• Bagged urine – unreliable gets contaminated, but negative sample may exclude UTI
• Clean catch
• Mid-stream
• Catheterised specimen
• Suprapubic aspiration

Following urine sample collection other investigations include:

• Urinalysis

Recurrent UTI investigations 

• KUB ultrasound (first-line) – Assess:
  • Fluid colelction
  • Bladder volume
  • Kidney size/shape
  • Urinary Tract obstruction/dilatation
• Micturating cystourethrogram (MCU) – contrast radiographic imaging – Confirm:
  • Posterior urethral valve
  • Obstructive uropathies
  • Diagnosing VUR
• Radoisotope nuclear imaging (DMSA and MAG3) – Confirm:
  • Renal damage

Diagnosis

Classification

• Asymptomatic Vs. Symptomatic
• Anatomically
• Single vs. Recurrent

Treatment

The main aim of management is to prevent sepsis.

Non pharmacological

• Hydration
• Improve bowel habits
• Improve hygiene

Pharmacological

• IV Broad spectrum antibiotics – gentamycin + benzylpenicillen
  • Switch to ceftriaxone if worried of nephrotoxicity and oxotocitiy from gentamycin
• Broad spectrum oral antibiotics (if appropriate) – Trimethoprim OR Cephalexin
  • Tailor antibiotics after organisms has been cultured and antibiotic sensitivity established

Surgical

Complications and Prognosis

Prognosis

• 10-30% will have recurrence within 12 months

Urinary Tract Abnormalities

Vesicoureteric reflux

• Disorder in which urine passes in a retrograde direction from the bladder through the vesicoureteric junction into the ureter
• Distal end of ureter runs less obliquely through the wall of the bladder → less muscle around it → retrograde urine flow during micturition → ureteric dilation
• Sometimes associated with renal malformation (renal scarring, dysplasia, reflux-associated nephropathy), excessive dilation & tortuosity of the ureter, and abnormalities of bladder function (premature detrusor contractions → urgency, wetting, poor bladder emptying)
• Common, affecting 40% of children <1yo who are investigated for a first UTI
• Diagnosis: MCU
• VUR often resolves spontaneously, although UTIs still often occur periodically throughout life

Posterior urethral valves

• Aka congenital obstructive posterior urethral membranes (COPUMs)
• Affects males, causing obstruction to urine flow at the level of the posterior urethra
• Bladder is often thick-walled & trabeculated
• There may be associated VUR with tortuous & dilated ureters draining hydronephrotic kidneys
• Presentation: antenatal USS demonstrating hydronephrosis & megacystitis is a common, as is UTI in early infancy, and some present later with dribbling & wetting
• Diagnosis: urethrogram phase of MCU + cystoscopy
• Tx: complex surgical procedures

Duplication

• Kidney has 2 separate collecting systems
  • Ureters may join before entry into the bladder, or they may have separate openings
  • One of the ureters may enter directly into the urethra → incontinence
• Often has VUR

Pelvicoureteric junction (puj) obstruction

• Commonly diagnosed following evaluation of hydronephrosis on antenatal scanning of the fetus
  • 9/10 cases will resolve spontaneously over the first year of life
  • F/U: periodic renal ultrasound DPTA or MAG3 radioisotope scans
• May present later in life with renal colic (→ usually require surgery)
• Vesicoureteric junction (VUJ) obstruction
  • Presentation: often following Ix of UTI with USS showing dilated ureter & MAG3 scan showing delayed passage of urine from the ureter into the bladder
  • Tx: stenting of VUJ or re-implantation of ureter
• Renal calculi
  • Presentation: following UTI (usually triple phosphate calculi/stone – Mg, Ca, ammonium with Proteus infection) or renal colic
  • Other stones occasionally encountered: cystine (autosomal recessive cystinuria), calcium oxalate, and uncommonly, uric acid
• Antenatal renal abnormalities: 1 in 200 infants have renal pelvis diameter (detected on 18/40 scan)

References

White, B 2011, Diagnosis and Treatment of Urinary Tract Infections in Children, American Family Physician, vol. 83, no. 4, pp. 409-415.
Royal Child Hospital Melbourne Australia Guidelines
Desai, D 2016, Paediatric urinary tract infections: Diagnosis and treatment, The Royal Australian College of General Practitioners, vol. 45, no. 8, pp. 558-564.