Spontaneous Bacterial Peritonitis

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 > 100^oF) 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 2 gm 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)

For More on this Topic Checkout:

• 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.
• EMRAP: C3 Live Paracentesis Video
• LITFL: Spontaneous Bacterial Peritonitis
• SinaiEM: SBP Pearls
• REBEL EM: Should You Give Albumin in Spontaneous Bacterial Peritonitis (SBP)?

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 Rezaie (Twitter: @srrezaie)

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