Pediatric UTI Antibiotic Treatment
For most pediatric UTIs, start with oral amoxicillin-clavulanate, cephalosporins (cefixime or cephalexin), or trimethoprim-sulfamethoxazole (if local E. coli resistance is <10%) for 7-14 days, reserving parenteral therapy only for toxic-appearing children, neonates, or those unable to tolerate oral medications. 1
Age-Based Treatment Algorithm
Neonates (<28 days)
- Hospitalize and treat parenterally with ampicillin + gentamicin or third-generation cephalosporin for 14 days total 1, 2
- These infants require supportive care and close monitoring due to higher bacteremia risk 1
Infants (28 days to 3 months)
- Well-appearing infants: Oral cefixime 8 mg/kg once daily or cephalexin 50-100 mg/kg/day divided into 4 doses for 7-14 days 1
- Ill-appearing infants: Ceftriaxone 50 mg/kg IV/IM every 24 hours until afebrile for 24 hours, then transition to oral therapy to complete 14 days 1, 2
Children (>3 months)
For Febrile UTI/Pyelonephritis:
First-line oral options (if child can tolerate oral medications): 1
Parenteral option (for toxic appearance, vomiting, or uncertain compliance): Ceftriaxone 50 mg/kg IV/IM every 24 hours 1
Duration: 7-14 days total (10 days most common) 1
For Non-Febrile UTI/Cystitis:
- First-line: Nitrofurantoin (preferred as it spares broader-spectrum agents) 1
- Alternatives: Same oral options as above 1
- Duration: 7-10 days (shorter than febrile UTI) 1
Critical Treatment Principles
Timing Matters
- Start antibiotics within 48 hours of fever onset to reduce renal scarring risk by >50% 1
- Early treatment is essential to prevent long-term complications including hypertension and chronic kidney disease 1
Antibiotic Selection Considerations
- Always consider local resistance patterns: Use trimethoprim-sulfamethoxazole only if E. coli resistance is <10% for pyelonephritis or <20% for lower UTI 1
- Adjust therapy based on culture results when available 1
- E. coli accounts for approximately 85% of pediatric UTIs 5
Diagnostic Requirements Before Treatment
- Obtain urine culture BEFORE starting antibiotics via catheterization or suprapubic aspiration in non-toilet-trained children (never use bag specimens for culture) 1
- For toilet-trained children, use midstream clean-catch specimen 1
- Diagnosis requires both pyuria AND ≥50,000 CFU/mL of a single uropathogen 1
Imaging Recommendations
First Febrile UTI
- Obtain renal and bladder ultrasound (RBUS) for all children <2 years to detect anatomic abnormalities 1
- No routine imaging for children >2 years with first uncomplicated UTI 1
- VCUG is NOT recommended routinely after first UTI 1
Second Febrile UTI
- Perform VCUG to evaluate for vesicoureteral reflux 1
Other Indications for Imaging
- Fever persisting >48 hours on appropriate therapy 1
- RBUS showing hydronephrosis or scarring 1
- Non-E. coli organisms 1
Follow-Up Strategy
Short-Term (1-2 days)
- Clinical reassessment within 24-48 hours to confirm fever resolution and clinical improvement 1
- If fever persists beyond 48 hours, reevaluate for antibiotic resistance or anatomic abnormalities 1
Long-Term
- No routine scheduled visits after successful treatment of first uncomplicated UTI 1
- Instruct parents to seek prompt evaluation (within 48 hours) for any future febrile illnesses 1
Common Pitfalls to Avoid
- Never use nitrofurantoin for febrile UTI/pyelonephritis as it doesn't achieve adequate serum/parenchymal concentrations 1
- Never treat febrile UTI for <7 days as shorter courses are inferior 1
- Never use bag specimens for culture due to 85% false-positive rate 1
- Never delay obtaining culture before antibiotics as this is your only opportunity for definitive diagnosis 1
- Never routinely prescribe antibiotic prophylaxis after first UTI, as it doesn't reduce recurrence risk even in mild-moderate VUR 1, 5
Antibiotic Prophylaxis
Routine prophylaxis is NOT recommended after first UTI or for children with VUR grades I-IV 1
Consider prophylaxis only for:
- Recurrent febrile UTIs (≥2 episodes) 1
- High-grade VUR with recurrent infections 1
- Bowel and bladder dysfunction with VUR 1
The RIVUR trial showed prophylaxis reduced recurrence by 50% but did not reduce renal scarring 1