| Indication for Therapy | Usual Causative Organisms | Antimicrobial Regimens |
|---|---|---|
| Community-acquired, uncomplicated (non-perforated appendicitis, perforations without established infection) | Enterobacterales, anaerobes, +/- Gram-positive cocci (stomach/duodenum) | cefTRIAXone 1g IV q24h + metroNIDAZOLE 500 mg IV/PO q12h |
β-lactam allergy (anaphylaxis): ciprofloxacin 400/500 mg IV/PO q12h |
||
Community-acquired, complicated, mild-to-moderate (perforated appendicitis, diverticulitis) |
Enterobacterales, anaerobes (including B. fragilis) | cefTRIAXone 1g IV q24h + metroNIDAZOLE 500 mg IV/PO q12h |
β-lactam allergy (anaphylaxis): ciprofloxacin 400/500 mg IV/PO q12h |
||
Community-acquired complicated, severe (shock, new organ failure, ICU patient) |
Enterobacterales, anaerobes (including B. fragilis) | cefTRIAXone 1g IV q24h + |
| piperacillin-tazobactam 3.375 g IV q6h | ||
β-lactam allergy (anaphylaxis): ciprofloxacin 400/500 mg IV/PO q12h |
||
Healthcare-associated, mild-to-moderate (hospitalized ≥ 5 days, anastomotic leak, post-operative abscess, recent antibiotics, recent hospitalization) |
Enterobacterales, anaerobes, Enterococcus spp., +/- drug-resistant gram-negative bacilli | cefTRIAXone 1 g IV q24h + |
| piperacillin-tazobactam 3.375 g IV q6h | ||
β-lactam allergy (anaphylaxis): vancomycinβ 20 mg/kg IV x1 dose, then 15 mg/kg IV
q12h + |
||
Healthcare-associated, severe (hospitalized ≥ 5 days, anastomotic leak, shock, ICU, recent antibiotics, recent hospitalization) |
Enterobacterales, anaerobes, Enterococcus spp., +/- drug-resistant gram- negative bacilli | piperacillin-tazobactam 3.375 g IV q6h |
β-lactam allergy (anaphylaxis): vancomycinβ 20 mg/kg IV x1 dose, then 15 mg/kg IV q12h + ciprofloxacin 400/500 mg IV/PO q12h + |
||
β-lactam allergy (non-anaphylaxis): meropenem 1 g IV q8h |
||
Biliary tract (e.g. acute cholangitis), mild-to-moderate |
Enterobacterales, anaerobes, Streptococcus spp., and Enterococcus spp.*† | cefTRIAXone 1 g IV q24h +/- |
β-lactam allergy (anaphylaxis): ciprofloxacin 400/500 mg IV/PO q12h +/- |
||
Biliary tract, severe (severe physiological disturbance, advanced age, immunocompromised state, or bilio-enteric anastomosis) |
Enterobacterales, anaerobes, Streptococcus spp., Enterococcus spp.* | piperacillin-tazobactam 3.375 g IV q6h |
β-lactam allergy (anaphylaxis): vancomycin‡ 20 mg/kg IV x1 dose, then 15 mg/kg IV q12h + ciprofloxacin 400/500 mg IV/PO q12h + |
||
| Prophylaxis for spontaneous bacterial peritonitis | Enterobacterales, S. pneumoniae, Streptococcus spp. | Short term (e.g. GI bleed): cefTRIAXone 1 g IV q24h x 7 days |
Long term (e.g. previous episode of SBP or ascitic fluid protein <10 g/L): co-trimoxazole 1 DS (trimethoprim [TMP] 160 mg/sulfamethoxazole [SMX] 800 mg) PO daily OR ciprofloxacin 500 mg PO daily |
* Cephalosporins alone are not active against Enterococcus species.
† Community-acquired biliary infection, activity against enterococci is not required, because the pathogenicity of enterococci has not been demonstrated. For selected health care associated infections or immunosuppressed patients, particularly those with hepatic transplantation, enterococcal infection may be significant and require treatment.
‡ vancomycin dosing based on actual body weight.
After source control is complete and there is resolution of clinical signs of infection (normalization of WBC count and absence of fever), antimicrobials can be discontinued. This can be as short as 24 hours after uncomplicated intra-abdominal infections or 4-7 days for complicated intra-abdominal infections. If source control is achieved, longer durations of therapy have not been associated with improved outcomes.
Patients undergoing cholecystectomy for acute cholecystitis should have antimicrobial therapy discontinued within 24 hours unless there is evidence of infection outside the wall of the gallbladder.
Solomkin J et al. Diagnosis and management of complicated intra-abdominal infections in adults and children: guidelines by the Surgical Infection Society and the Infectious Diseases Society of America. Clin Infect Dis. 2010; 50:133-64.
Antibiotics for complicated intra-abdominal infections. Pharmacist’s Letter/Prescriber’s Letter. 2010; 26(3):260321.
Toronto Antimicrobial Stewardship Corridor (TASC). Best Practice in General Surgery: Management of Intra-Abdominal Infections, Dec 2011.