Antibiotic Regimens for Intra-abdominal Infections in Children

Introduction to Antibiotic Selection

• The American Academy of Pediatrics and the Infectious Diseases Society of America recommend acceptable broad-spectrum antimicrobial regimens for pediatric patients with complicated intra-abdominal infections, including an aminoglycoside-based regimen, a carbapenem, a β-lactam/β-lactamase–inhibitor combination, or an advanced-generation cephalosporin with metronidazole 1, 2, 3

Selection Criteria for Antimicrobial Therapy

• The choice of specific antimicrobial therapy should be guided by the origin of infection, such as community-acquired vs. healthcare-associated, and the severity of illness, such as mild-moderate vs. severe physiologic disturbance 1, 3, 4
• The safety profile of the antibiotic, including consideration of age-specific safety concerns, should also be taken into account when selecting antimicrobial therapy 1, 2

First-line Antibiotic Options

• Piperacillin-tazobactam is recommended at a dose of 200–300 mg/kg/day of the piperacillin component, divided every 6–8 hours 1
• Ticarcillin-clavulanate is recommended at a dose of 200–300 mg/kg/day of the ticarcillin component, divided every 4–6 hours 1, 2
• Meropenem is recommended at a dose of 60 mg/kg/day, divided every 8 hours 1, 3
• Imipenem-cilastatin is recommended at a dose of 60–100 mg/kg/day, divided every 6 hours 1, 2
• Ertapenem is recommended at a dose of 15 mg/kg twice daily for children 3 months to 12 years, and 1 g/day for children ≥13 years 1
• Cefotaxime is recommended at a dose of 150–200 mg/kg/day, divided every 6–8 hours, plus metronidazole at a dose of 30–40 mg/kg/day, divided every 8 hours 1, 3
• Ceftriaxone is recommended at a dose of 50–75 mg/kg/day, divided every 12–24 hours, plus metronidazole at a dose of 30–40 mg/kg/day, divided every 8 hours 1, 2
• Ceftazidime is recommended at a dose of 150 mg/kg/day, divided every 8 hours, plus metronidazole at a dose of 30–40 mg/kg/day, divided every 8 hours 1, 3
• Cefepime is recommended at a dose of 100 mg/kg/day, divided every 12 hours, plus metronidazole at a dose of 30–40 mg/kg/day, divided every 8 hours 1, 2
• Gentamicin is recommended at a dose of 3–7.5 mg/kg/day, divided every 8–24 hours, plus metronidazole at a dose of 30–40 mg/kg/day, divided every 8 hours 1, 3
• Tobramycin is recommended at a dose of 3.0–7.5 mg/kg/day, divided every 8–24 hours, plus metronidazole at a dose of 30–40 mg/kg/day, divided every 8 hours 1, 2

Special Considerations

• For children with severe reactions to β-lactam antibiotics, ciprofloxacin at a dose of 20-30 mg/kg/day, divided every 12 hours, plus metronidazole at a dose of 30–40 mg/kg/day, divided every 8 hours, is recommended 1, 2
• For neonates with necrotizing enterocolitis, recommended regimens include ampicillin + gentamicin + metronidazole, ampicillin + cefotaxime + metronidazole, or meropenem as monotherapy 1, 2

Duration of Therapy

• Antimicrobial therapy should generally be limited to 4-7 days unless source control is difficult to achieve 5
• Longer durations of therapy have not been associated with improved outcomes 5

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, 4
• β-Lactam antibiotic dosages should be maximized if undrained intra-abdominal abscesses may be present 1, 3
• Antibiotic serum concentrations and renal function should be monitored when using aminoglycosides or vancomycin 1, 2
• 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 7
• Using cefotetan or clindamycin due to increasing resistance among Bacteroides fragilis group 7
• Continuing antibiotics beyond 7 days when adequate source control has been achieved 5, 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 7, 6