Organism-Specific Therapeutic Regimens
Treatment regimens are included below for the most common isolates associated with acute appendicitis. Guideline-directed therapy focuses on the empiric treatment of these organisms, which includes Escherichia coli and other coliforms, anaerobes, and gram-positive cocci. Thus, organism-specific therapeutic regimens for appendicitis include coverage for anaerobic organisms (including Bacteroides fragilis, Clostridium spp, and Prevotella spp), aerobic gram-negative bacilli (including E coli, Klebsiella spp, and Proteus mirabilis), Pseudomonas aeruginosa, streptococci, enterococci, and mixtures of aerobes and anaerobes. [1, 2, 3, 4]
A single-drug, broad-spectrum antibiotic such as piperacillin-tazobactam or multidrug regimens may be initially necessary to achieve wide-spectrum coverage of multiple organisms. Later, therapy can be further narrowed on the basis of sensitivities if microbiology culture data become available to the healthcare provider. [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, Peptostreptococcus spp)
Lincomycins
-
Clindamycin 600 mg IV q8h or
Nitroimidazoles
-
Metronidazole 500 mg IV q8h or
Carbapenems
-
Ertapenem 1 g IV q24h or
Penicillin/beta lactamase
-
Ampicillin-sulbactam 3 g IV q6h or
-
Ticarcillin-clavulanate 3.1 g IV q4-6h or
Combination cephalosporin/beta lactamase/nitroimidazole
-
Ceftolozane/tazobactam 1.5 g IV q8h plus metronidazole 500 mg IV q8h
Facultative aerobic gram-negative bacilli (including E coli, Klebsiella spp, P mirabilis)
Carbapenems
Penicillins
-
Ampicillin 2 g IV q4h or
Fluoroquinolones
-
Ciprofloxacin 400 mg IV q12h or
-
Levofloxacin 750 mg IV q24h or
Cephalosporins
-
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
Combination cephalosporin/beta lactamase/nitroimidazole
-
Ceftolozane/tazobactam1.5 g IV q8h plus metronidazole 500 mg IV q8h or
Lincomycins
-
Gentamicin 5-7 mg/kg IV q24h
Pseudomonas aeruginosa
Carbapenems
Fluoroquinolones
-
Ciprofloxacin 400 mg IV q12h or
Beta lactamase
-
Piperacillin-tazobactam 4.5 g IV q6h or
Carbapenem/dehydropeptidase inhibitor
-
Imipenem-cilastatin 500 mg IV q6h or
Combination cephalosporin/beta lactamase/nitroimidazole
-
Ceftolozane/tazobactam1.5 g IV q8h plus metronidazole 500 mg IV q8h
Streptococci and enterococci
Penicillin/beta lactamase
-
Ampicillin-sulbactam 3 g IV q6h or
-
Ticarcillin-clavulanate 3.1 g IV q4-6h or
Beta lactamase
-
Piperacillin-tazobactam 3.375-4.5 g IV q6-8h or
Carbapenems
Carbapenem/dehydropeptidase inhibitor
-
Imipenem-cilastatin 500 mg IV q6h or
Combination cephalosporin/beta lactamase/nitroimidazole
-
Ceftolozane/tazobactam 1.5 g IV q8h plus metronidazole 500 mg IV q8h
Mixed flora: aerobes and anaerobes
Cephalosporins
Beta lactamase
-
Piperacillin-tazobactam 3.375-4.5 g IV q6h or
Penicillin/beta lactamase
-
Ampicillin-sulbactam 3 g IV q6h or
-
Ticarcillin-clavulanate 3.1 g IV q4-6h or
Fluoroquinolones
-
Moxifloxacin 400 mg IV q24h or
Carbapenems
Carbapenem/dehydropeptidase inhibitor
-
Imipenem-cilastatin 500 mg IV q6h