What is the first-line antibiotic treatment for pediatric urinary tract infections (UTIs)?

First-Line Antibiotic Treatment for Pediatric Urinary Tract Infections

Amoxicillin-clavulanate and trimethoprim-sulfamethoxazole are the first-line antibiotics for empiric treatment of pediatric urinary tract infections, with the choice guided by local antimicrobial resistance patterns. 1

Age-Based Recommendations

Newborns and Young Infants (< 3 months)

• Parenteral therapy is recommended with either:
  • Ampicillin plus an aminoglycoside (gentamicin) 1
  • Ampicillin plus a third-generation cephalosporin (cefotaxime, ceftazidime) 1, 2
• Once clinically improved and afebrile for 24 hours, transition to oral therapy to complete a 14-day course 2

Infants and Children (3 months - 24 months)

• Oral therapy is appropriate for most patients who are not toxic-appearing and can tolerate oral intake 1
• First-line options include:
  • Amoxicillin-clavulanate (20-40 mg/kg/day in 3 doses) 1
  • Trimethoprim-sulfamethoxazole (6-12 mg/kg trimethoprim and 30-60 mg/kg sulfamethoxazole per day in 2 doses) 1, 3
• For children unable to tolerate oral medications or who appear toxic, parenteral therapy should be initiated 1

Older Children (> 2 years)

• Oral therapy with similar agents as above is appropriate 1, 4
• Treatment duration:
  • Pyelonephritis (febrile UTI): 7-14 days 1
  • Cystitis (lower UTI): 5-7 days 2, 4

Antibiotic Selection Considerations

Local Resistance Patterns

• Knowledge of local E. coli resistance patterns is essential before selecting empiric therapy 1
• E. coli resistance to ampicillin alone has increased significantly (up to 75% in some regions), making it unsuitable as monotherapy 1, 5
• Resistance rates should be <10% for treating pyelonephritis and <20% for lower UTIs 1

Clinical Severity

• Patients who are toxic-appearing or unable to tolerate oral intake should receive parenteral therapy initially 1
• Options for parenteral therapy include:
  • Ceftriaxone (75 mg/kg every 24h) 1
  • Gentamicin (7.5 mg/kg/day divided every 8h) 1
  • Cefotaxime (150 mg/kg/day divided every 6-8h) 1

Special Considerations

• Nitrofurantoin should not be used for febrile UTIs/pyelonephritis as it doesn't achieve adequate tissue concentrations 1
• For suspected or confirmed ESBL-producing organisms, amikacin may be effective as it maintains activity against most ESBL strains 6
• Fluoroquinolones are generally avoided in pediatric patients due to safety concerns and increasing resistance 1

Monitoring and Follow-up

• Clinical improvement should occur within 24-48 hours of appropriate therapy 1
• Urine culture and sensitivity results should guide adjustment of empiric therapy 1
• Renal and bladder ultrasonography is recommended for febrile infants with UTIs to detect anatomic abnormalities 1

Common Pitfalls

• Using nitrofurantoin for febrile UTIs/pyelonephritis (inadequate tissue penetration) 1
• Continuing empiric therapy without adjusting based on culture results 1
• Failing to consider local resistance patterns when selecting empiric therapy 1, 5
• Using short-course therapy (1-3 days) for febrile UTIs, which has been shown to be inferior 1
• Not addressing constipation, which can contribute to recurrent UTIs 4

Emerging Concerns

• Increasing rates of multidrug-resistant E. coli in pediatric UTIs, with resistance to two or more antibiotics reported in 15-27% of isolates across different age groups 5
• The most common co-resistance pattern is ampicillin/trimethoprim-sulfamethoxazole, which affects empiric therapy choices 5