Pediatric Appendicitis Organism-Specific Therapy 

Updated: Dec 07, 2017
Author: Simon S Rabinowitz, MD, PhD, FAAP; Chief Editor: Thomas E Herchline, MD 

Organism-Specific Therapy

Organism-specific therapeutic regimens for appendicitis in children are outlined below, including those for anaerobic organisms (including Bacteroides fragilis, Clostridium species [spp], and Prevotella spp), aerobic gram-negative bacilli (including Escherichia coli, Klebsiella spp, and Proteus mirabilis), Pseudomonas aeruginosa,streptococci, enterococci, and mixtures of aerobes and anaerobes. Historically, extended spectrum antibiotics were used for complicated appendicitis.[1, 2, 3, 4, 5, 6, 7, 8, 9]

A comprehensive retrospective study that included almost 25,000 children aged 3-18 years discharged from 2011-2013 from 23 freestanding children’s hospitals concluded that extended-spectrum antibiotics seem to offer no advantage over narrower-spectrum agents for children with surgically managed acute uncomplicated or complicated appendicitis.[10]  The authors suggest that this observation is consistent with the failure of pseudomonas or other highly resistant gram negative organisms to frequently play an etiologic role in the morbidity associated with complicated or uncomplicated acute appendicitis. Given the rising frequency of resistant organisms and the increased cost of the extended spectrum antibiotics, unless a specific organism has been identified, narrow spectrum should be used as empiric therapy.[11, 12, 13]

Anaerobic organisms (including Bacteroides fragilis, Clostridium spp, Prevotella spp)

Recommendations are as follows:

  • Clindamycin 20-40 mg/kg/day IV divided q6-8h or

  • Metronidazole 30-40 mg/kg/day IV divided q8h or

  • Ampicillin-sulbactam 200 mg/kg/day (based on ampicillin component) IV/IM divided q6h or

  • Ticarcillin-clavulanate 200-300 mg/kg/day (based on ticarcillin component) IV divided q4-6h

Aerobic gram-negative bacilli (including Escherichia coli, Klebsiella spp, Proteus mirabilis)

Recommendations are as follows:

  • Aztreonam 90-120 mg/kg/day IV divided q6-8h or

  • Ampicillin 200 mg/kg/day IV divided q12h or

  • Cefoxitin 80-160 mg/kg/day IV divided q4-6h or

  • Cefotetan 40-80 mg/kg/day IV divided q12h or

  • Cefotaxime 150-200 mg/kg/day IV divided q6-8h or

  • Ceftriaxone 50-75 mg/kg IV q24h

Pseudomonas aeruginosa

Recommendations are as follows:

  • Aztreonam 90-120 mg/kg/day IV divided q6-8h or

  • Piperacillin-tazobactam 200-300 mg/kg/day (based on piperacillin component) IV divided q6h or

  • Imipenem-cilastin 60-100 mg/kg/day IV divided q6h or

  • Meropenem 60 mg/kg/day IV divided q8h

Streptococci and enterococci

Recommendations are as follows:

  • Ampicillin-sulbactam 200 mg/kg/day (based on ampicillin component) IV/IM divided q6h or

  • Ticarcillin-clavulanate 200-300 mg/kg/day (based on ticarcillin component) IV divided q4-6h or

  • Piperacillin-tazobactam 200-300 mg/kg/day (based on piperacillin component) IV divided q6-8h or

  • Imipenem-cilastin 60-100 mg/kg/day IV divided q6h or

  • Meropenem 60 mg/kg/day IV divided q8h

Mixtures of aerobes and anaerobes

Recommendations are as follows:

  • Cefoxitin 80-160 mg/kg/day IV divided q4-6h or

  • Cefotetan 40-80 mg/kg/day IV divided q12h or

  • Ticarcillin-clavulanate 200-300 mg/kg/day (based on ticarcillin component) IV divided q4-6h or

  • Piperacillin-tazobactam 200-300 mg/kg/day (based on piperacillin component) IV divided q6-8h or

  • Ampicillin-sulbactam 200 mg/kg/day (based on ampicillin component) IV/IM divided q6h or

  • Imipenem-cilastin 60-100 mg/kg/day IV divided q6h or

  • Meropenem 60 mg/kg/day IV divided q8h