Management of Pediatric Urinary Tract Infection
For children 2-24 months with suspected febrile UTI, obtain urine by catheterization or suprapubic aspiration for culture, start empiric oral antibiotics immediately (cephalosporin or amoxicillin-clavulanate) for 7-14 days, and obtain renal ultrasound—but skip VCUG unless there's a second febrile UTI or abnormal ultrasound findings. 1, 2, 3
Diagnostic Approach: Age-Specific Collection Methods
Infants <2 Months
- Obtain urine by catheterization or suprapubic aspiration only—bag specimens are unreliable with 85% false-positive rates 2, 4
- These infants require hospitalization and parenteral antibiotics (ampicillin + gentamicin or third-generation cephalosporin) for 14 days total 2
- Higher risk of serious bacterial infection necessitates more aggressive management 4
Children 2-24 Months (Non-Toilet-Trained)
- Catheterization or suprapubic aspiration for culture before starting antibiotics 1, 2
- Alternative: obtain bag/clean-catch for urinalysis screening first; if positive, then catheterize for culture 1
- This two-step approach avoids unnecessary catheterization in 90% of febrile children who don't have UTI 1
Toilet-Trained Children >2 Years
- Clean-catch midstream urine is acceptable for both urinalysis and culture 2, 3
- Must clean external genitalia first to minimize contamination 5
Diagnostic Criteria
UTI diagnosis requires BOTH:
- Pyuria: ≥5 WBC/HPF on centrifuged specimen OR positive leukocyte esterase 2, 3
- Culture: ≥50,000 CFU/mL of single uropathogen from catheterized specimen (or ≥100,000 CFU/mL from voided specimen) 1, 2
Urinalysis interpretation:
- Positive nitrite has 98-100% specificity for UTI 2
- Negative for both leukocyte esterase AND nitrite effectively rules out UTI in bag specimens 5
Antibiotic Treatment Algorithm
First-Line Oral Options (Well-Appearing Children)
- Cephalosporins: Cefixime 8 mg/kg once daily OR cephalexin 50-100 mg/kg/day divided q6h 2
- Amoxicillin-clavulanate: 40-45 mg/kg/day divided q12h 2
- Trimethoprim-sulfamethoxazole: ONLY if local E. coli resistance <10% for febrile UTI 2
Parenteral Therapy Indications
Use ceftriaxone 50 mg/kg IV/IM once daily if: 2
- Toxic appearance
- Unable to retain oral intake
- Age <3 months
- Uncertain compliance
Treatment Duration
- Febrile UTI/pyelonephritis: 7-14 days (10 days most common) 1, 2, 3
- Non-febrile UTI/cystitis: 7-10 days 2, 3
- Never treat febrile UTI for <7 days—shorter courses are inferior 2
Critical Medication Pitfall
Never use nitrofurantoin for febrile UTI—it doesn't achieve adequate serum/parenchymal concentrations to treat pyelonephritis 2, 3
Imaging Recommendations: Evidence-Based Algorithm
Age <2 Months, First Febrile UTI
- Renal/bladder ultrasound: Rating 9/9 (usually appropriate) 1
- VCUG: Rating 6/9 (may be appropriate)—consider in boys and if ultrasound abnormal 1
Age 2 Months to 6 Years, First Febrile UTI with Good Response
- Renal/bladder ultrasound: Rating 7/9 (usually appropriate), though yield is low if prenatal third-trimester ultrasound was normal 1
- VCUG: Rating 4/9 (may be appropriate)—NOT routine 1
Age >6 Years, First Febrile UTI with Good Response
- Renal/bladder ultrasound: Rating 5/9 (disagreement among experts) 1
- VCUG: Rating 3/9 (usually not appropriate) 1
Atypical or Recurrent Febrile UTI (Any Age)
Obtain BOTH studies: 1
- Renal/bladder ultrasound: Rating 9/9 (complementary procedure)
- VCUG: Rating 7/9 (complementary procedure)
Atypical features requiring imaging:
- Poor response to antibiotics within 48 hours
- Septic appearance
- Poor urine stream
- Elevated creatinine
- Non-E. coli organism 1
DMSA Renal Cortical Scintigraphy
- Rating 6/9 for atypical/recurrent UTI—use 4-6 months after UTI to detect scarring 1
- Not a first-line test 1
Follow-Up Strategy
Short-Term (1-2 Days)
Clinical reassessment within 24-48 hours is mandatory to confirm: 2
- Fever resolution
- Clinical improvement
- Treatment response
If fever persists >48 hours on appropriate antibiotics, consider: 2
- Antibiotic resistance
- Anatomic abnormalities
- Abscess formation
Long-Term
- No routine scheduled visits after successful treatment of first uncomplicated UTI 2, 3
- Instruct parents to seek evaluation within 48 hours for any future febrile illness 2
- After second febrile UTI: Obtain VCUG to evaluate for vesicoureteral reflux 2, 3
Antibiotic Prophylaxis: Current Evidence
Routine prophylaxis is NOT recommended for: 2
- First UTI
- VUR grades I-IV
- Isolated hydronephrosis
The RIVUR trial showed: 2
- Prophylaxis reduced recurrent UTI by 50% in children with VUR
- BUT did not reduce renal scarring
- Consider selectively only in high-risk patients (recurrent UTI, high-grade VUR)
Clinical Context: Long-Term Outcomes
Renal scarring occurs in 15% after first UTI 1, 2
- Contrary to earlier beliefs, scarring accounts for only 5% of childhood hypertension 1
- Reflux nephropathy causes only 3.5% of end-stage renal disease in children 1
- Many "scars" attributed to pyelonephritis are actually congenital dysplasia identified on prenatal ultrasound 1
Early treatment matters:
- Treatment within 48 hours of fever onset reduces renal scarring risk by >50% 2
- This drives the urgency of prompt diagnosis and treatment 2
Common Pitfalls to Avoid
- Using bag specimens for culture—70% specificity yields 85% false-positive rate 2
- Failing to obtain culture before antibiotics—eliminates opportunity for definitive diagnosis 2, 3
- Treating asymptomatic bacteriuria—selects for resistant organisms 3
- Ordering routine imaging for first uncomplicated UTI in children >2 years—not indicated and increases costs/radiation 3
- Using fluoroquinolones in children—musculoskeletal safety concerns; reserve for severe infections only 2
- Delaying treatment in febrile UTI—increases renal scarring risk 2, 3