Urinary Tract Infection

Urinary Tract Infection is one of the most common bacterial infections seen in infants and children. UTI with fever indicates an upper tract infection/pyelonephritis, while cystitis is not usually accompanied by fever. It is important to diagnose and empirically treat febrile UTIs in infants and children, as delayed treatment may increase the risk of bacteremia. Risk factors associated with increased rates of UTI in young children include age, female gender, and constipation. An evidence-based decision tool has been developed to assess risk factors and help with urine result interpretation.^1,2,3

For infants less than 2 months, refer to TREKK’s Bottom Line Recommendations for Fever in Young Infants.

• Infants/non-verbal children may have fever without apparent source, increased crying, vomiting, poor feeding or other non- specific symptoms.
• Children > 2 years typically have urinary symptoms such as dysuria, abdominal/back pain, new incontinence, +/- fever.
• Infants/children with a viral syndrome (e.g., bronchiolitis) or other source of infection should NOT be routinely tested for UTI.

URINALYSIS (UA):

• Obtain sample from a midstream urine. For infants, use a clean catch method ^4,5 or a “bagged” urine specimen.
• In and out bladder catheterization can be used if required (e.g., low urine output) but carries the risk of pain and iatrogenic UTI. If a catheter specimen is obtained, reserve some urine for culture, if needed.
• Either Biochemistry lab urinalysis or a dipstick point of care test can be used for urinalysis.
• If urinalysis is normal, do NOT send a urine culture, as any positive cultures are then most likely contaminants.

MICROSCOPY:

• Urine microscopy reports WBC per High Power Field (HPF) and is useful to help support the diagnosis, especially in the setting of an equivocal urinalysis (either leukocyte esterase (LE) OR nitrites positive).

URINE CULTURE:

• Obtain specimen from a clean catch/midstream sample, in and out catheterization or suprapubic aspiration. A bag sample should NEVER be sent for culture.
• Urine cultures should be sent to the lab as soon as possible, ideally within 4 hours. If there is any delay, store the sample in a refrigerator to avoid false positives.

OTHER INVESTIGATIONS:

• In well-appearing infants/children, bloodwork is typically not required.
• Obtain CBC, blood culture, urea, and creatinine in any infant/child who is unwell (i.e., poor feeding, persistent irritability, vomiting). Refer to TREKK’s Sepsis PedsPac for infants/children who appear toxic and/or have signs of hypoperfusion. Perform a lumbar puncture in any infant/child with clinical signs/symptoms of meningitis (refer to TREKK’s Meningitis BLR).
• Consider gonorrhea, chlamydia, and HSV testing if dysuria and possible/confirmed history of a sexual encounter.

INTERPRETING URINALYSIS

• A normal UA has good negative predictive value with a < 1% risk of UTI. Look for other causes of illness.
• If positive LE and positive nitrites, send culture and start antibiotics. Microscopy is optional in this circumstance.
• If negative LE and positive nitrites, send microscopy (if available) and culture. Defer antibiotics pending culture.
• If positive LE and negative nitrites, send microscopy (if available) and culture. Defer antibiotics pending culture.
• Pyuria (>5-10 WBC/HPF) usually correlates with presence of LE. Absence of pyuria is rare in UTI unless upper tract obstruction. Small amounts of pyuria alone (without nitrites or LE) can be due to any systemic inflammatory condition. Please visit our website at trekk.ca for more information.

INTERPRETING URINE CULTURE

• Urine culture results should be interpreted in the context of the clinical history and the UA/microscopy results.
• UTIs typically have significant growth of a single uropathogen:
  • ≥50 x 10⁶ OR ≥50 x 10⁷ colony forming units (CFU)/L from a catheter/suprapubic aspirate specimen

OR

• • ≥100 x 10⁶ OR ≥100 x 10⁷ CFU/L from a midstream urine specimen

• The clinical diagnosis of UTI in an infant/child is supported by BOTH a POSITIVE urinalysis (and pyuria on microscopy, if performed) AND a POSITIVE culture with significant growth of a single uropathogen.
• A smaller colony count of <5 x 10⁷ CFU/L or multiple bacteria with a normal urinalysis/microscopy usually indicates contamination.

• In a first febrile UTI, the most likely bacteria is E. coli.
• For children with a history of previous UTIs, determine empiric therapy by the result of the most recent urine culture and
  sensitivities

DURATION OF THERAPY

• For uncomplicated afebrile cystitis in adolescents: 3-5 days (see table above)
• For uncomplicated febrile UTI: 7 days
• For febrile UTI in patients with a known urological structural abnormality: 10 days

• Children who are still febrile or have persistent dysuria after 24-48 hours of appropriate therapy should be reassessed:
  • Verify culture results for bacterial sensitivities
  • Consider IV antibiotics and admission to hospital
  • Consider renal ultrasound to detect complications such as renal abscess, focal pyelonephritis/nephronia
• At discharge, communicate to family and primary care provider that all infants > 2-12 months with a first febrile UTI should have a renal and bladder ultrasound to detect renal structural abnormalities/high grade vesicoureteral reflux.
• Discuss modifiable risk factors for urinary tract infections such as constipation and sexual activity, when appropriate.

Thank you to the following content experts who led the development of the Urinary Tract Infection Bottom Line Recommendations:

Nicole Le Saux, MD, FRCP(C), Professor, University of Ottawa, Division of Infectious Diseases. Children’s Hospital of Eastern Ontario (CHEO)

Gina Neto, MD, FRCPC, Medical Director and Division Chief, Emergency Medicine. Children’s Hospital of Eastern Ontario (CHEO)

Thank you to the TREKK Editorial Committee and the following people who supported the development of this resource:

TREKK Editorial Lead: Dr. Sarah Reid (CHEO, University of Ottawa)
TREKK Knowledge Broker: Mary Anne Nurmi, BA, MSc (University of Manitoba)

To see our resource development process please visit our website here.

(as cited in the Urinary Tract Infection Bottom Line Recommendations):

1. University of Pittsburgh. UTICalc – for children 2 to 23 months of age. 2023. Accessed online: July 24, 2023.
2. Montini G, Tullus K, Hewitt I. Febrile urinary tract infections in children. N Engl J Med. 2011;365(3):239-250.
3. Urinary tract infection in under 16s: diagnosis and management. London: National Institute for Health and Excellence (NICE); October 2018.
4. Kaufman J, Tosif S, Fitzpatrick P, et al. Quick wee: a novel non-invasive urine collection method. Emerg Med J. 2017;34(1):63-64.
5. Herreros Fernández, M. L., González Merino, N., Tagarro Garciáa, A., Peárez Seoane, B., De La Serna Martínez, M., Contreras Abad, M. T., & Garciáa-Pose, A . A new technique for fast and safe collection of urine in newborns. Archives of Disease in Childhood, 98(1), 27–29.
6. Roberts KB, Subcommittee on Urinary Tract Infection, Steering Committee on Quality Improvement and Management. Urinary tract infection: Clinical practice guidelines for the diagnoses and management of the unitial UTI in febrile infants and children 2 to 24 months. Pediatrics. 2011;128(3):595-610.
7. Robinson JL, Finlay JC, Lang ME, Bortolussi R; Canadian Paediatric Society, Infectious Diseases and Immunization Committee, Community Paediatrics Committee. Urinary tract infections in infants and children: Diagnosis and management. Paediatr Child Health. 2014;19(6):315-325.

For a complete list of the evidence that informed the creation of the Urinary Tract Infection Bottom Line Recommendations see the Evidence Repository here.

The purpose of this document is to provide healthcare professionals with key facts and recommendations for the diagnosis and treatment of community acquired pneumonia in children in the emergency department. The TREKK Network is not liable for any damages, claims, liabilities, costs or obligations arising from the use of this document including loss or damages arising from any claims made by a third party. THIS DOCUMENT IS SUBJECT TO FULL DISCLAIMER HERE: trekk.ca/terms-of-use