January 20, 2020

Spontaneous Bacterial Peritonitis (SBP)

Definition: Acute infection of the ascitic fluid in a patient with liver disease without another source of infection

Epidemiology: (Runyon 1988, Runyon 1988, Borzio 2001)

  • Incidence
    • 10-25% risk of at least one episode per year
    • 20% risk in those with ascites admitted to the hospital
  • Historically, mortality ~ 50%

Pathophysiology:

  • Not completely understood
  • Increased portal systemic hypertension
    • Causes mucosal edema of the bowel wall
    • Increases transmural migration of enteric organisms into the ascitic fluid
  • Impaired phagocytic function in the liver
  • Impaired immunologic activity in ascitic fluid

Presentation:

  • Classic triad: fever, abdominal pain and increasing ascites. Presence of all three components uncommon
  • Symptoms
    • Fever or chills
    • Abdominal pain
    • Abdominal swelling
    • Fatigue
    • Malaise
  • Signs
    • Abdominal tenderness variable
      • Typically diffuse
      • Can be mild without peritoneal signs
      • Can be severe with rebound and/or guarding
    • Abdominal distension
    • Altered mental status (from hepatic encephalopathy)

Diagnostics:

  • Obtaining an ascitic fluid sample is critical in making the diagnosis
  • Serum blood tests (i.e. WBC, CRP, ESR) are not helpful in making this diagnosis
  • Due to variable presentations and considerable mortality associated with SBP, consideration should be made to perform paracentesis on ALL patients with ascitic fluid who are being admitted (Gaetano 2016)
  • Diagnostic paracentesis (EM: RAP HD)
  • Ascitic fluid assays
    • Cell count
      • Look for WBC > 250-500 cells/mm3 or neutrophil count > 250 cells/mm3
      • Peritoneal dialysis patients: neutrophil count > 100 cells/mm
    • pH < 7.34 more common in SBP (Wong 2008)
    • Ascitic fluid gram stain (rarely positive) and culture
  • If patient has fever (temp > 100oF) or abdominal pain/tenderness, empiric antibiotics should be given even if neutrophil count < 250 cells/mm3

Management:

  • Antibiotics
    • Most common bacterial causes: E. Coli, S. Pneumoniae, Enterococci
    • 3rd Generation Cephalosporin covers vast majority of cases
      • Ceftriaxone 25 mg/kg up to 1 – 2gm daily
      • Cefotaxime 25 mg/kg up to 1 gm Q8
    • Alternate antibiotic choices
      • Ciprofloxacin 400mg IV BID
      • Levofloxacin 750mg IV daily
      • Piperacillin/Tazobactam 4.5g IV TID
      • Ertapenem 1g IV qD
      • Imipenem/Cilastatin 500mg IV QID
  • Albumin Infusion (Runyon 2012)
    • Recommended by American Association for the Study of Liver Disease (AASLD) in specific subgroups with SBP
      • Presence of any of the following should prompt albumin administration
      • Serum creatinine > 1 mg/dL
      • Blood urea nitrogen (BUN) > 30 mg/dL
      • Total Bilirubin > 4 mg/dL
    • Impact of albumin infusion (Sort 1999)
      • 25% reduction in renal failure
      • 20% reducing n mortality
    • Dose
      • 1.5 grams/kg within 6 hours
      • 1.0 grams/kg on day 3 of treatment
  • Patients with a single episode of SBP should be considered for antibiotic prophylaxis (with norfloxacin, ciprofloxacin or TMP/SMX) (Runyon 2012)

Take Home Points:

  • SBP is a difficult diagnosis to make because presentations are variable. Consider a diagnostic paracentesis in all patients presenting to the ED with ascites from cirrhosis
  • An ascites PMN count > 250 cells/mm3 is diagnostic of SBP but treatment should be considered in any patient with ascites and abdominal pain or fever
  • Treatment of SBP is with a 3rd generation cephalosporin with the addition of albumin infusion in any patient meeting AASLD criteria (Cr > 1.0 mg/dL, BUN > 30 mg/dL or Total bilirubin > 4 mg/dL)

REBEL Review Card – SBP

Read More:

Oyama LC: Disorders of the liver and biliary tract, in Marx JA, Hockberger RS, Walls RM, et al (eds): Rosen’s Emergency Medicine: Concepts and Clinical Practice, ed 8. St. Louis, Mosby, Inc., 2010, (Ch) 90: p 1186-1205.

References:

  1. Runyon BA et al. Ascitic fluid analysis in malignancy‐related ascites. Hepatology 1988; 8(5): 1104-1109. PMID: 3417231
  2. Runyon BA. Spontaneous bacterial peritonitis: An explosion of information. Hepatology 1988; 8: 171–175. PMID: 3338704
  3. Borzio M et al. Bacterial infection in patients with advanced cirrhosis: a multicentre prospective study. Dig Liver Dis 2001; 33(1): 41-48. PMID: 11303974
  4. Gaetano et al. The benefit of paracentesis on hospitalized adults with cirrhosis and ascites. Journal of Gastroenterology and Hepatology 2016. PMID: 26642977
  5. Wong CL et al. Does this patient have bacterial peritonitis or portal hypertension? How do I perform a paracentesis and analyze the results? JAMA 2008; 299(10):1166-78. PMID: 18334692
  6. Runyon BA. Management of Adult Patients with Ascites Due to Cirrhosis: Update 2012. AASLD Practice Guideline. Link
  7. Sort P et al. Intravenous albumin in patients with cirrhosis and spontaneous bacterial peritonitis. NEJM 1999; 341: 1773-4. PMID: 10432325

Post Peer Reviewed By: Salim R. Rezaie, MD (Twitter: @srrezaie)

Cite this article as: Anand Swaminathan, "Spontaneous Bacterial Peritonitis (SBP)", REBEL EM blog, January 20, 2020. Available at: https://rebelem.com/spontaneous-bacterial-peritonitis-sbp/.
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Anand Swaminathan

Clinical Assistant Professor of Emergency Medicine at St. Joe's Regional Medical Center (Paterson, NJ)
REBEL EM Associate Editor and Author

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