What is the best antibiotic regimen for treating intra-abdominal infections in children?

Best Antibiotic Regimens for Intra-abdominal Infections in Children

For pediatric patients with complicated intra-abdominal infections, acceptable broad-spectrum antimicrobial regimens include an aminoglycoside-based regimen, a carbapenem (imipenem, meropenem, or ertapenem), a β-lactam/β-lactamase–inhibitor combination (piperacillin-tazobactam or ticarcillin-clavulanate), or an advanced-generation cephalosporin (cefotaxime, ceftriaxone, ceftazidime, or cefepime) with metronidazole. 1

Selection Criteria for Antimicrobial Therapy

The choice of specific antimicrobial therapy should be guided by:

• Origin of infection: Community-acquired vs. healthcare-associated 1
• Severity of illness: Mild-moderate vs. severe physiologic disturbance 1
• Safety profile: Consideration of age-specific safety concerns 1

First-line Antibiotic Options

β-lactam/β-lactamase Inhibitor Combinations

• Piperacillin-tazobactam: 200–300 mg/kg/day of piperacillin component, divided every 6–8 hours 1, 2

  • Provides excellent coverage against both aerobic and anaerobic pathogens 2, 3
  • FDA-approved for children 2 months and older with intra-abdominal infections 2
  • Clinical trials show equivalent efficacy to cefotaxime plus metronidazole in pediatric intra-abdominal infections 4

• Ticarcillin-clavulanate: 200–300 mg/kg/day of ticarcillin component, divided every 4–6 hours 1

Carbapenems

• Meropenem: 60 mg/kg/day, divided every 8 hours 1
• Imipenem-cilastatin: 60–100 mg/kg/day, divided every 6 hours 1
• Ertapenem: For children 3 months to 12 years: 15 mg/kg twice daily (not to exceed 1 g/day); For children ≥13 years: 1 g/day 1, 5

Advanced-generation Cephalosporin + Metronidazole

• Cefotaxime: 150–200 mg/kg/day, divided every 6–8 hours + Metronidazole: 30–40 mg/kg/day, divided every 8 hours 1
• Ceftriaxone: 50–75 mg/kg/day, divided every 12–24 hours + Metronidazole: 30–40 mg/kg/day, divided every 8 hours 1
• Ceftazidime: 150 mg/kg/day, divided every 8 hours + Metronidazole: 30–40 mg/kg/day, divided every 8 hours 1
• Cefepime: 100 mg/kg/day, divided every 12 hours + Metronidazole: 30–40 mg/kg/day, divided every 8 hours 1

Aminoglycoside-based Regimens

• Gentamicin: 3–7.5 mg/kg/day, divided every 8–24 hours + Metronidazole: 30–40 mg/kg/day, divided every 8 hours 1
• Tobramycin: 3.0–7.5 mg/kg/day, divided every 8–24 hours + Metronidazole: 30–40 mg/kg/day, divided every 8 hours 1

Special Considerations

β-lactam Allergies

• For children with severe reactions to β-lactam antibiotics:
  • Ciprofloxacin: 20-30 mg/kg/day, divided every 12 hours + Metronidazole: 30–40 mg/kg/day, divided every 8 hours 1
  • Alternatively, an aminoglycoside-based regimen as described above 1

Neonates with Necrotizing Enterocolitis

• Recommended regimens include:
  • Ampicillin + Gentamicin + Metronidazole 1
  • Ampicillin + Cefotaxime + Metronidazole 1
  • Meropenem as monotherapy 1
  • Consider Vancomycin instead of ampicillin for suspected MRSA or ampicillin-resistant enterococcal infection 1
  • Add Fluconazole or Amphotericin B if fungal infection is suspected 1

Duration of Therapy

• Antimicrobial therapy should generally be limited to 4-7 days unless source control is difficult to achieve 1, 6
• Longer durations have not been associated with improved outcomes 1, 6

Important Clinical Pearls

• Routine use of broad-spectrum agents is not indicated for all children with fever and abdominal pain when there is low suspicion of complicated appendicitis or other acute intra-abdominal infection 1
• β-Lactam antibiotic dosages should be maximized if undrained intra-abdominal abscesses may be present 1
• Antibiotic serum concentrations and renal function should be monitored when using aminoglycosides or vancomycin 1
• Source control through surgical intervention or drainage remains the cornerstone of treatment for intra-abdominal infections 6
• Initial inadequate antimicrobial therapy is associated with increased morbidity and mortality 6

Common Pitfalls to Avoid

• Using ampicillin-sulbactam due to high rates of resistance among community-acquired E. coli 1, 6
• Using cefotetan or clindamycin due to increasing resistance among Bacteroides fragilis group 1, 6
• Continuing antibiotics beyond 7 days when adequate source control has been achieved 1, 6
• Failing to adjust therapy based on culture results once available 6
• Using overly broad-spectrum antibiotics for mild-to-moderate community-acquired infections, which may increase toxicity and facilitate acquisition of resistant organisms 1, 6