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.
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:
Clindamycin 600 mg IV q8h or
Metronidazole 500 mg IV q8h or
Ertapenem 1 g IV daily or
Ampicillin-sulbactam 3 g IV q6h or
Ticarcillin-clavulanate 3.1 g IV q4-6h or
Ceftolozane/tazobactam 1.5 g IV q8h plus metronidazole 500 mg IV q8h
Aerobic gram-negative bacilli (including Escherichia coli, Klebsiella spp, Proteus mirabilis)
See the list below:
Aztreonam 1-2 g IV q8h or
Ampicillin 2 g IV q4h for or
Ciprofloxacin 400 mg IV q12h or
Ertapenem 1 g IV daily or
Levofloxacin 750 mg IV q24h or
Gentamicin 5-7 mg/kg IV q24h or
Cefoxitin 2g IV q8h or
Cefotetan 2 g IV q12h or
Cefotaxime 1-2 g IV q6-8h or
Ceftriaxone 1-2g IV q24h or
Ceftolozane/tazobactam 1.5 g IV q8h plus metronidazole 500 mg IV q8h
Pseudomonas aeruginosa
See the list below:
Aztreonam 1-2 g IV q8h or
Ciprofloxacin 400 mg IV q12h or
Piperacillin-tazobactam 4.5 g IV q6h 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
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