What is the initial management of a paediatric urinary tract infection (UTI)?

Initial Management of Pediatric Urinary Tract Infection

The initial management of a pediatric urinary tract infection requires obtaining an appropriate urine specimen through catheterization or suprapubic aspiration before starting antimicrobial therapy, followed by empiric treatment with an appropriate antibiotic for 7-14 days based on local sensitivity patterns. 1

Diagnosis

Obtaining Urine Specimens

1. For febrile infants requiring immediate antimicrobial therapy (due to ill appearance or other pressing reasons):

   • Obtain urine specimen for both culture and urinalysis through catheterization or suprapubic aspiration (SPA) before administering antimicrobials 1
   • Bag specimens are not acceptable for culture due to high false-positive rates (12-83%) 2

2. For febrile infants not requiring immediate therapy:

   • Assess likelihood of UTI based on risk factors:

     • Female gender (2× higher risk than circumcised males)
     • Uncircumcised males (4-20× higher risk than circumcised males)
     • White race
     • Fever ≥39°C or lasting >48 hours
     • No apparent source of fever (doubles risk to ~7.5%) 1, 2

   • If low likelihood of UTI: clinical follow-up without testing is sufficient

   • If not low likelihood: Either:

     • Option 1: Obtain urine via catheterization/SPA for culture and urinalysis
     • Option 2: Obtain urine by convenient method for urinalysis first; if positive (leukocyte esterase, nitrite, or microscopy showing leukocytes/bacteria), then obtain catheterization/SPA specimen for culture 1

Diagnostic Criteria

• Definitive diagnosis: Positive urine culture with ≥50,000 CFU/mL of a single uropathogen 1, 2
• Supporting evidence: Urinalysis showing pyuria (≥10 WBC/μL) or bacteriuria 1

Treatment

Antimicrobial Therapy

1. Route of administration:

   • Oral therapy is as effective as parenteral therapy for clinically stable children 1
   • Base route on practical considerations (e.g., inability to retain oral fluids may necessitate parenteral route) 1

2. First-line oral options for clinically stable children:

   • Cephalexin: 50-100 mg/kg/day divided in 4 doses
   • Cefixime: 8 mg/kg/day in 1 dose
   • Amoxicillin-clavulanate: 20-40 mg/kg/day in 3 doses 2

3. First-line parenteral options:

   • Ceftriaxone: 75 mg/kg every 24 hours
   • Cefotaxime: 150 mg/kg/day divided every 6-8 hours
   • Gentamicin: 7.5 mg/kg/day divided every 8 hours 2

4. Duration:

   • 7-14 days of therapy is recommended for febrile UTIs 2
   • Adjust antimicrobial choice based on culture results when available 1

5. Important considerations:

   • Avoid nitrofurantoin for febrile UTIs/pyelonephritis 2
   • Reserve fluoroquinolones as last resort due to safety concerns 2
   • For children <2 months, trimethoprim-sulfamethoxazole is not recommended 3, 4

Follow-up and Imaging

1. Clinical follow-up:

   • Expect clinical improvement within 48-72 hours of appropriate treatment 2
   • Instruct parents to seek medical evaluation within 48 hours for future febrile episodes 2

2. Imaging:

   • Renal and bladder ultrasound (RBUS) is recommended after first febrile UTI to detect anatomical abnormalities 1, 2
   • Routine voiding cystourethrogram (VCUG) is not recommended after first UTI unless ultrasound shows findings suggestive of high-grade vesicoureteral reflux or other abnormalities 2

Prevention of Complications

• Early detection and treatment are crucial to prevent renal scarring, which can occur in up to 40% of acute pyelonephritis cases 2, 5
• Address modifiable risk factors:
  • Correct voiding habits
  • Ensure adequate hydration
  • Treat constipation 2
• Do not treat asymptomatic bacteriuria as it may promote antimicrobial resistance 2

Common Pitfalls to Avoid

1. Diagnostic errors:

   • Relying on bag urine specimens for culture (high false-positive rates)
   • Failing to obtain urine culture before starting antimicrobials
   • Treating based on urinalysis alone without culture confirmation 1

2. Treatment errors:

   • Delaying treatment in febrile infants with suspected UTI
   • Using inappropriate antibiotics based on local resistance patterns
   • Treating asymptomatic bacteriuria 2, 5
   • Using nitrofurantoin for pyelonephritis (inadequate tissue penetration) 2

3. Follow-up errors:

   • Failing to adjust antibiotics based on culture results
   • Unnecessary imaging studies after first uncomplicated UTI
   • Not providing guidance to parents about when to seek care for recurrent symptoms 2

By following these evidence-based guidelines for the initial management of pediatric UTIs, clinicians can effectively diagnose and treat infections while minimizing complications and unnecessary interventions.