CPS Statement: Urinary Tract Infections

CPS Statement: Urinary Tract Infections

The following was adapted from the Canadian Paediatric Society’s (CPS) statement on “Urinary tract infection in infants and children: Diagnosis and management” and “Prophylactic antibiotics for children with recurrent urinary tract infections.” Please see the full statement for the full recommendations from the Canadian Paediatric Society.

Background:

Urinary tract infections (UTIs) are a common presentation in pediatrics. Approximately 7% of children ages 2 to 24 months who present with a fever without a source and 8% of children age 2 to 19 years who present with possible urinary symptoms are diagnosed with a UTI. The current CPS statement focuses on diagnosis and management of uncomplicated acute UTIs in infants and children >2 months of age. Complicated UTIs, such as recurrent UTIs, renal abnormalities or significant past medical history should be managed on a case-by-case basis.

Diagnosis:

UTI’s in infants and children can be difficult to recognize as they often present with non-specific symptoms such as increase irritability and fevers. Specific urinary symptoms include dysuria, urinary frequency, hematuria, abdominal pain, back pain or new daytime incontinence

Indications for Urinalysis: A lower threshold is needed for young  children.

  • Children <3 years of age:
    • Fever (>39.0C rectal) without a source - Urinalysis and urine culture should be obtained.
    • Fever with a source (rhinitis, cough, rash or diarrhea) – Viral infection is more likely the cause of fever and does not need to be investigated for a UTI.
  • Children > 3 years of age:
    • Urinary symptoms - Urinalysis and urine culture should be obtained.

Sampling Urine:

  • Children not yet toilet trained
    • Urethral catheterization – Gold standard
    • Suprapubic aspiration – If catheterization is not an option
    • Urine collection bag – High rates of contamination but can be done as a preliminary sample. If the sample culture returns negative, no further investigation is needed. If it returns positive, it provides a stronger case to perform a urethral catheterization.
  • Children toilet trained
    • Midstream urine sample – Gold standard (perineal cleansing may not be necessary)

Interpreting Urinalysis:

  • Macroscopic Urinalysis
    • Nitrite - Measures the conversion of dietary nitrate to nitrite by gram-negative bacteria
      • 53% sensitivity, 98% specificity
      • Positive test - Is highly indicative of a UTI caused by a gram-negative bacteria
      • Negative test - Does not rule out a UTI cause by gram-positive bacteria
    • Leukocyte Esterase - Indirect measure of pyuria
      • 83% sensitivity, 78% specificity
      • Can be falsely negative if there is a low concentration of leukocytes present
  • Microscopic Urinalysis
    • White Blood Cells
      • 73% sensitivity, 81% specificity
    • Bacteria
      • 81% sensitivity, 83% specificity
  • Bottom line: if there no nitrites, leukocyte esterase, pyuria or bacteruria are present, the child has <1% of having a UTI

Urine Cultures:

  • Common organisms in childhood UTI:
    • Escherichia coli, Kelbsiella pneumoniae, Enterobacter species, Citrobacter species, Serratia species
    • In adolescent females: Staphylococcus saprophyticus
  • Colony counts indicative of UTI
    • Midstream clean catch: > 10^5CFU/mL; mixed growth is usually indicative of contamination
    • In and out catheter: > 5x10^4CFU/mL; mixed growth is usually indicative of contamination
    • Suprapubic aspiration: any growth

Treatment:

If a UTI is highly suspected, the child should start on an empiric oral antibiotic therapy that covers the most common organisms then change to more targeted therapies once culture and sensitivity are available. Please see the complete guideline for for specific recommendations, or consult local resources that include local resistance patterns.

  • Oral Antibiotics: Cefixime, TMP/SMX, or Amoxicilin-Clavulanate
  • IV Antibiotics: Ceftriaxone or Gentamicin

Imaging:

Imaging should only be done if it will change management. The goal of imaging is to confirm that a child has pyelonephritis AND to identify any structural abnormalities or vesicoureteral reflux (VUR).

  • Renal/Bladder Ultrasound (RBUS)
    • Indication - All children <2 years of age with a first febrile UTI during or within 2 weeks of the infection.
    • Will identify grade IV or V VUR. Lower grades of VUR are unlikely to be clinically significant.
    • Pros: Convenient, inexpensive, readily available and less invasive.
  • Voiding Cystourethrogram (VCUG)
    • Indication – Abnormal RBUS or children <2 years of age with a second well-documented UTI.
    • Pros: Used to assess degree of VUR and the anatomy of male urethra Cons: Expensive, exposure to radiation, risk of causing a UTI.
  • Nuclear Cystogram (NCG)
    • Used to assess VUR if VCUG is not available.
    • Pros: Less radiation.
    • Cons: Less readily available, poor assessment of male urethra.

Prophylaxis:

Traditionally, children with VUR were given antibiotic prophylaxis to prevent UTIs and their long-term complications. However, recent studies have shown that most children who receive UTI prophylaxis do not benefit, with increase harm in antibiotic complications rather than benefits in reducing UTI complications. Rather than prophylaxis, parents should be educated on the sign and symptoms of a UTI recurrence and threshold for testing for UTI in these children should be low. In cases where prophylaxis is still used, such as with significant renal or urologic anomalies, trimethoprim/sulfamethoxazole or nitrofurantoin are agents of choice and it should be used for no longer than 3-6 months. If a urine culture shows an organism is resistant to a prophylactic antibiotic, prophylaxis should be stopped or changed.

Key Take-Home Points:

  1. When a child presents with a fever without a source, UTI should be considered in the differential diagnosis, as UTIs in children often do not have specific symptoms.
  2. Gold standard urine samples from children not yet toilet-trained are from in-and-out catheter or suprapubic aspiration. In children who are toilet-trained, the gold standard is mid-stream urine.
  3. Urinalysis that has an absence of nitrites, leukocyte esterase, pyuria (WBC) or bacteria, it is highly unlikely a child has a UTI.
  4. In a child with a UTI, start empiric oral antibiotics then step down according to culture and sensitivity. IV antibiotics are rarely indicated in children with uncomplicated UTIs.
  5. Not every child needs an ultrasound. Imaging is only indicated in a child <2 years with their first febrile UTI, or if there are signs that the UTI may be complicated.
Clinical Presentation: