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Peritonitis, Acute

Peritonitis, Acute is a topic covered in the 5-Minute Clinical Consult.

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  • Definition: inflammation of the peritoneum
  • Classification:
    • Aseptic: chemical irritation or systemic inflammation of peritoneum
    • Bacterial: infection of peritoneal fluid
  • Bacterial peritonitis types:
    • Primary/spontaneous bacterial peritonitis (SBP): infection of ascitic fluid in the absence of an intra-abdominal source; typically monomicrobial
    • Secondary bacterial peritonitis: infection of ascitic fluid from a detectable intra-abdominal source (i.e., perforation, abscess); typically polymicrobial
    • Tertiary bacterial peritonitis: persistent infection despite adequate therapy


  • In patients with ascites, the incidence of SBP in a 1-year period is 10–25% (1).
  • Secondary bacterial peritonitis correlates with incidence of the underlying pathology (e.g., colitis, appendicitis, diverticulitis, PUD).
  • 57% of patients with secondary bacterial peritonitis progress to tertiary peritonitis (2).

  • SBP: In asymptomatic patients with cirrhosis and ascites, the prevalence is <3% in outpatients and 8–36% in the nosocomial setting (3).
  • In patients with cirrhosis and ascites, 5% of peritonitis is secondary rather than SBP (4).

Etiology and Pathophysiology

  • Mechanism
    • SBP:
      • Bacterial translocation via lymphatic spread through mesenteric lymph nodes
      • Cirrhotic patients have secondary:
        • Alterations to gut microbiota with higher prevalence of pathogenic organisms
        • Small intestinal bacterial overgrowth (SIBO) and increased intestinal mucosal permeability to bacteria
        • Decreased cellular and humoral immunity limiting peritoneal bacterial clearance
    • Secondary bacterial peritonitis
      • Spillage/translocation of bacteria from inflamed or perforated intraperitoneal organs or introduction of bacterial through instrumentation—that is, peritoneal dialysis, intraperitoneal chemotherapy
    • Tertiary bacterial peritonitis
      • Evolves from secondary peritonitis if inadequate source control or altered host immunity
  • Microbiology
    • SBP
      • Escherichia coli (33%), Streptococcus spp. (15%), Staphylococcus (13%), Klebsiella (8%); reflects increasing rate of gram-positive and resistant organisms (e.g., extended-spectrum β-lactamase–producing [ESBL] E. coli, MRSA, Enterococcus) in the nosocomial setting (5)
    • Secondary bacterial peritonitis:
      • E. coli, Klebsiella, Proteus, Streptococcus, Enterococcus, Bacteroides, Clostridium

Risk Factors

  • SBP: advanced cirrhosis with ascites, malnutrition, upper GI bleed, PPI usage, prior SBP
    • Acid suppression with PPIs promotes SIBO increasing incidence of SBP. Patients hospitalized with cirrhosis who are receiving PPIs have increased risk of developing SBP (3,5).
    • 70% of SBP cases are seen in patients with Child-Pugh class C cirrhosis (1).
    • Low ascites protein level (<1.0 g/dL)
  • Factors associated with perforation or fluid translocation (e.g., peritoneal dialysis, Helicobacter pylori and NSAIDs causing ulcers, vascular disease causing bowel ischemia, ETOH abuse causing pancreatitis) increase risk for SBP

General Prevention

  • SBP prophylaxis beneficial when risk factors are present (e.g., ascitic fluid protein concentration <1.0 g/dL, esophageal varices, or history of previous SBP)
    • Prior SBP: prophylactic norfloxacin or Bactrim PO daily (6)[A]
    • Cirrhosis and GI bleed: 7-day course of ceftriaxone 2 g IV daily or norfloxacin BID; IV while bleeding, PO as tolerated (6)[A]
    • Cirrhotic ascites: low ascitic fluid protein (<1.5 g/dL) with renal impairment (creatinine ≥1.2, BUN ≥25, or serum Na ≤130) or liver failure (Child score ≥9, bilirubin ≥3): prophylactic norfloxacin PO daily (3,6)[A]
  • Limit use of PPIs to only proven indications (6)[B].

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Stephens, Mark B., et al., editors. "Peritonitis, Acute." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2019. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816228/all/Peritonitis__Acute.
Peritonitis, Acute. In: Stephens MB, Golding J, Baldor RA, et al, eds. 5-Minute Clinical Consult. 27th ed. Wolters Kluwer; 2019. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816228/all/Peritonitis__Acute. Accessed April 26, 2019.
Peritonitis, Acute. (2019). In Stephens, M. B., Golding, J., Baldor, R. A., & Domino, F. J. (Eds.), 5-Minute Clinical Consult. Available from https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816228/all/Peritonitis__Acute
Peritonitis, Acute [Internet]. In: Stephens MB, Golding J, Baldor RA, Domino FJ, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2019. [cited 2019 April 26]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816228/all/Peritonitis__Acute.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Peritonitis, Acute ID - 816228 ED - Stephens,Mark B, ED - Golding,Jeremy, ED - Baldor,Robert A, ED - Domino,Frank J, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/816228/all/Peritonitis__Acute PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -