Appendicitis Organism-Specific Therapy 

Updated: Jan 14, 2015
  • Author: Kara E Hennelly, MD; Chief Editor: Thomas E Herchline, MD  more...
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Organism-Specific Therapeutic Regimens

Organism-specific therapeutic regimens for appendicitis in adults are outlined below, including those for anaerobic organisms (including Bacteroides fragilis, Clostridium 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. [1, 2, 3, 4]

See Appendicitis: Avoiding Pitfalls in Diagnosis, a Critical Images slideshow, to help make an accurate diagnosis.

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

See the list below:

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

See the list below:

Pseudomonas aeruginosa

See the list below:

Streptococci and enterococci

See the list below:

  • Ampicillin-sulbactam 3 g IV q6h or
  • Ticarcillin-clavulanate 3.1 g IV q4-6h or
  • Piperacillin-tazobactam 3.375-4.5 g IV q6-8h or
  • Doripenem 500 mg IV q8h or
  • Imipenem-cilastatin 500 mg IV q6h or
  • Meropenem 1 g IV q8h or
  • Ceftolozane/tazobactam 1.5 g IV q8h plus metronidazole 500 mg IV q8h

Mixture of aerobes and anaerobes

See the list below:

  • Cefoxitin 2g IV q8h or
  • Cefotetan 2 g IV q12h or
  • Ticarcillin-clavulanate 3.1 g IV q4-6h or
  • Piperacillin-tazobactam 3.375-4.5 g IV q6-8h or
  • Ampicillin-sulbactam 3 g IV q6h or
  • Doripenem 500 mg IV q8h or
  • Imipenem-cilastatin 500 mg IV q6h or
  • Meropenem 1 g IV q8h or
  • Ertapenem 1 g IV daily or
  • Moxifloxacin 400 mg IV q24h