Several classifications exist for prediction of acute pancreatitis severity. A commonly used classification system (the Atlanta classification) divides acute pancreatitis into two broad categories:

  1. Mild (edematous and interstitial acute) pancreatitis.
  2. Severe (usually referred to as “acute necrotizing”) pancreatitis. For detailed guidance on staging please refer to VIHA online resources such as Up-To-Date.


No prophylactic or empiric antibiotic therapy is required unless there is a documented infection.


  • The administration of prophylactic antibiotics to patients with severe necrotizing pancreatitis prior to the diagnosis of infection is NOT recommended.
  • Initiate antimicrobial therapy in proven secondary infection or when the patient is hemodynamically unstable and requiring vasopressors.
  • It not possible to differentiate necrotizing pancreatitis from infected necrotizing pancreatitis on the basis of a CT scan alone. Fine needle aspirate is required.
  • Surgical debridement and drainage with culture is essential for established infections.
  • Blood cultures recommended (high risk of bacteremia).

Usual Pathogens
Enterococcus spp.
S. aureus
Coagulase negative Staphylococcus

Recommended Empiric Therapy (Duration based on clinical improvement)

Piperacillin-tazobactam 3.375 g IV q6h OR Imipenem 500 mg IV q6h

Penicillin allergic (clear history)

Ciprofloxacin 400 mg IV q12h + Metronidazole 500 mg IV q8h + Vancomycin 15 mg/kg (round to nearest 250 mg) IV q12h.
Adjust vancomycin interval based on GFR.