What antibiotic is recommended for a child with a urinary tract infection (UTI)?

Antibiotic Treatment for Pediatric UTI

For children with urinary tract infections, antibiotic selection depends critically on age: infants under 2 months require parenteral ampicillin plus either gentamicin or ceftazidime; infants 2-3 months need parenteral ceftriaxone initially; and children over 3 months can be treated with oral amoxicillin-clavulanate or trimethoprim-sulfamethoxazole as first-line agents. 1, 2

Age-Stratified Treatment Approach

Infants 8-21 Days Old

• Parenteral therapy is mandatory with ampicillin IV/IM (150 mg/kg/day divided every 8 hours) PLUS either ceftazidime IV/IM (150 mg/kg/day divided every 8 hours) OR gentamicin IV/IM (4 mg/kg every 24 hours) 3
• These infants require hospitalization due to risk of serious bacterial infection 3

Infants 22-28 Days Old

• Ceftriaxone IV/IM (50 mg/kg once daily) is the recommended empiric therapy 3
• Parenteral therapy should continue until clinical improvement and afebrile for 24 hours 4

Infants 29-60 Days Old

• Ceftriaxone IV/IM (50 mg/kg once daily) for initial therapy 3
• Oral antibiotics may be considered for infants older than 28 days who are not clinically toxic: cephalexin 50-100 mg/kg/day in 4 doses OR cefixime 8 mg/kg/day in 1 dose 3

Children 3 Months to 24 Months

• First-line oral options: amoxicillin-clavulanate OR trimethoprim-sulfamethoxazole 1, 2
• Dosing for trimethoprim-sulfamethoxazole: 40 mg/kg sulfamethoxazole and 8 mg/kg trimethoprim per 24 hours, divided every 12 hours 5, 6
• Parenteral therapy indicated if: clinically toxic appearance, unable to retain oral intake, or uncertain compliance 1

Treatment Duration

• 7-14 days total duration is recommended for pediatric UTI 1
• Neonates and young infants typically require 14 days of therapy 4
• Older children with uncomplicated cystitis may complete therapy in 5-7 days if responding well 4
• Clinical improvement should occur within 24-48 hours of appropriate therapy 2

Critical Selection Considerations

Local Resistance Patterns

• Antibiotic selection must be guided by local antimicrobial sensitivity patterns 1
• E. coli resistance to amoxicillin alone is high, making it a poor empiric choice 1
• Amoxicillin-clavulanate and nitrofurantoin generally maintain high susceptibility rates 1

Route of Administration Decision Points

• Parenteral therapy is necessary when:
  • Child appears clinically toxic 1
  • Unable to retain oral medications (vomiting) 1
  • Uncertain medication compliance 1
  • Age less than 2-3 months 3

Common Pitfalls and Caveats

• Never use nitrofurantoin for febrile UTIs or pyelonephritis due to inadequate tissue penetration 1, 2
• Avoid fluoroquinolones in children due to safety concerns affecting tendons, muscles, joints, and nervous system 1
• Do not treat asymptomatic bacteriuria as treatment may be harmful 1
• Amoxicillin alone should not be used empirically due to high E. coli resistance rates 1
• Treatment should only be initiated after confirmation of UTI through appropriate diagnostic criteria 1

Follow-up and Monitoring

• Renal and bladder ultrasonography is recommended for all young children with first febrile UTI to detect anatomic abnormalities 1, 2
• Adjust empiric therapy based on urine culture and sensitivity results 2
• If no clinical improvement within 24-48 hours, reassess diagnosis and antibiotic choice 2