Recommended Antibiotics for Pediatric UTI
First-Line Oral Antibiotics for Uncomplicated UTI
For most children with uncomplicated UTI, use amoxicillin-clavulanate, cephalosporins (cefixime, cephalexin), or trimethoprim-sulfamethoxazole as first-line oral therapy for 7-14 days, with oral therapy being equally effective as parenteral treatment when the child can tolerate oral medications. 1, 2
Specific Antibiotic Choices by Clinical Presentation
For febrile UTI/pyelonephritis:
- Amoxicillin-clavulanate 40-45 mg/kg/day divided every 12 hours 1
- Cefixime 8 mg/kg/day in 1 dose 1, 3
- Cephalexin 50-100 mg/kg/day in 4 divided doses 1
- Trimethoprim-sulfamethoxazole ONLY if local E. coli resistance is <10% 4, 1
For non-febrile cystitis:
- Nitrofurantoin is preferred for uncomplicated cystitis as it spares broader-spectrum agents 4, 1
- Same oral options as above can be used 1, 2
Treatment Duration
Febrile UTI/pyelonephritis requires 7-14 days of treatment, with 10 days being the most commonly recommended duration. 1, 2 Shorter courses (1-3 days) are inferior and should be avoided for febrile UTI 1, 2. For non-febrile cystitis, 7-10 days is adequate, though shorter courses (3-5 days) may be comparable in children >2 years 1.
When to Use Parenteral Therapy
Reserve parenteral antibiotics for:
- Toxic-appearing children 1, 2
- Inability to retain oral intake or medications 1, 2
- Age <3 months 1
- Uncertain compliance with oral therapy 1, 2
Parenteral options:
- Ceftriaxone 50 mg/kg IV/IM every 24 hours 1
- Ampicillin + gentamicin for neonates <28 days 4, 5
- Third-generation cephalosporin for infants 28 days to 3 months 4, 5
Age-Specific Considerations
Neonates (<28 days):
- Require hospitalization and parenteral ampicillin + aminoglycoside or third-generation cephalosporin for 14 days total 4, 5
Infants 28 days to 3 months:
- If clinically ill: hospitalize with parenteral third-generation cephalosporin or gentamicin 5
- If well-appearing: may use outpatient parenteral therapy (ceftriaxone daily) until afebrile 24 hours, then complete 14 days with oral antibiotics 5
Children >6 months:
- Third-generation cephalosporin for uncomplicated pyelonephritis 4
- Oral therapy acceptable if not toxic-appearing 1, 2
Critical Antibiotic Selection Pitfalls
Never use nitrofurantoin for febrile UTI/pyelonephritis as it does not achieve adequate serum/parenchymal concentrations to treat kidney infection 1, 2. Nitrofurantoin is only appropriate for uncomplicated cystitis 4, 1.
Always consider local resistance patterns - the guideline threshold is <10% resistance for pyelonephritis and <20% for lower UTI 4, 1. Trimethoprim-sulfamethoxazole resistance in E. coli can reach 19-63% in some regions 2.
Avoid fluoroquinolones in children due to musculoskeletal safety concerns; reserve only for severe infections where benefits outweigh risks 1.
Adjusting Therapy
Always adjust antibiotics based on urine culture and sensitivity results when available 1, 2. Obtain urine culture BEFORE starting antibiotics - this is your only opportunity for definitive diagnosis 1. Clinical improvement should occur within 24-48 hours of appropriate therapy 1, 2; if fever persists beyond 48 hours, reevaluate for treatment failure, antibiotic resistance, or anatomic abnormalities 1.
Imaging After First UTI
**Obtain renal and bladder ultrasound (RBUS) for all children <2 years with first febrile UTI** to detect anatomic abnormalities 1, 2. For children >2 years with first uncomplicated UTI and good response to treatment, routine imaging is NOT indicated 1, 2. Voiding cystourethrography (VCUG) is NOT recommended routinely after first UTI, but should be performed after a second febrile UTI 1, 2.