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Spontaneous bacterial peritonitis (Primary peritonitis)


Spontaneous bacterial peritonitis (SBP) is a bacterial infection of ascitic fluid that occurs in the absence of an identifiable intraabdominal source of infection. It is the most common bacterial infection and a leading cause of hospital admission and mortality among patients with cirrhosis. Enteric gram-negative bacteria (e.g., E. coli, Klebsiella spp.) have historically been the most common isolates; however, gram-positive, fluoroquinolone-resistant, and multidrug-resistant bacteria are increasingly common. SBP may manifest with fever, abdominal pain, and/or altered mental status, but some patients are asymptomatic at presentation. Diagnosis is based on the finding of elevated ascitic fluid neutrophil count (≥ 250/mm3) without an intraabdominal surgically-treatable source of infection. Timely antibiotic administration is the mainstay of therapy. Empiric antibiotic choice depends on the setting of infection (i.e., community-acquired infection vs. healthcare-associated infection), previous antibiotic exposure, and local bacterial susceptibility patterns. IV albumin supplementation is used as adjunctive therapy for selected high-risk patients. Long-term prophylactic antibiotic therapy is recommended to prevent recurrent infection.


  • Spontaneous bacterial peritonitis: : infection of the ascitic fluid in the absence of any focal intraabdominal, surgically treatable source of infection [1]
  • Secondary bacterial peritonitis: inflammation of the peritoneum caused by bacterial infection from a surgically treatable intraabdominal source [2]


  • Most common bacterial infection in patients with cirrhosis. [3]
  • Represents over 30% of bacterial infections among hospitalized patients with cirrhosis. [4]
  • Prevalence among asymptomatic outpatients with decompensated cirrhosis is estimated to be up to 3.5% [5]

Epidemiological data refers to the US, unless otherwise specified.


Risk factors [3]

SBP in adults occurs almost exclusively in patients with cirrhosis and ascites. [6]

Pathophysiology [3][7]

  • Bacterial translocation from the intestinal lumen to mesenteric lymph nodes spread to systemic and portal circulation colonization and subsequent infection of ascitic fluid
  • Contributing factors related to underlying portal hypertension and cirrhosis:
    • Intestinal dysmotility
    • Bacterial overgrowth
    • Altered intestinal permeability
    • Systemic immune dysfunction

Microbiology [3][7]

SBP is typically a monomicrobial bacterial infection. The presence of multiple organisms on ascitic fluid gram-stain or culture should raise suspicion for secondary bacterial peritonitis.

Clinical features

Symptoms and signs of SBP may be subtle or absent.

  • Diffuse abdominal pain/tenderness
  • Fever and chills
  • Worsening ascites
  • New-onset or worsening encephalopathy
  • Nausea, vomiting
  • Constipation or diarrhea (peristaltic signs sparse or absent in cases of ileus)


SBP is diagnosed when the ascitic fluid neutrophil count is ≥ 250/mm3, with or without positive ascitic fluid bacterial cultures, and in the absence of another intraabdominal source of infection. SBP is often asymptomatic and a high index of suspicion is essential in any patient with cirrhosis and ascites. [3]

Approach [2][10]

Laboratory studies

Diagnostic paracentesis [2][10][3]

SBP is diagnosed when the ascitic fluid neutrophil count is ≥ 250/mm3 in the absence of another intraabdominal source of infection. The diagnosis of SBP does not require positive ascitic fluid cultures.


Imaging tests are not required for diagnosis but may be indicated in patients with new-onset or worsening ascites (see ”Diagnostics” in “Cirrhosis”) or if secondary bacterial peritonitis is suspected (see “Differential diagnosis” section).


Antimicrobial therapy [2][10]

Empiric antibiotic therapy

Empiric antibiotic therapy for spontaneous bacterial peritonitis [2][10]
Patient characteristics Recommended regimen for patients with cirrhosis

Community-acquired infection

and no recent beta-lactam antibiotic exposure

Healthcare-associated infection,

suspected resistant pathogen,

and/or recent beta-lactam antibiotic exposure [2][10]

Management of bacterascites [2][10]

Adjunctive therapy [2][10]

  • IV albumin supplementation [2]
    • Indications (any of the following): [26]
  • Consider discontinuing beta blockers. [3][27]
  • Discontinue diuretics. [3]
  • Avoid potentially nephrotoxic medications (e.g., NSAIDs). [3]
  • Consider discontinuing proton-pump inhibitors. [28]

Supportive therapy

Monitoring and subsequent management [2][10]

  • Serial abdominal examination
  • Repeat paracentesis: not routinely recommended
    • Indications (any of the following): [2]
      • The patient does not have advanced cirrhosis (i.e., when SBP is a suspected or confirmed complication of ascites due to causes other than cirrhosis).
      • SBP developed in the hospital (i.e., nosocomial infection).
      • Recent beta-lactam antibiotic exposure
      • Atypical ascitic fluid chemistry: total protein > 1 g/dL, LDH ≥ upper limit of normal for serum, or glucose < 50 mg/dL
      • Atypical growth on initial ascitic fluid culture (e.g., polymicrobial)
      • Lack of symptom resolution (e.g., ongoing fever and/or abdominal pain) despite antibiotic therapy
    • Timing: 48 hours after initiation of antibiotics
    • Worsening of signs and symptoms; and/or lack of significant reduction in ascitic fluid neutrophil count (by at least 25%) after initiation of antibiotics; indicates a potential failure of first-line antibiotic therapy and should raise suspicion of secondary bacterial peritonitis (see “Differential diagnosis” section).
  • Consider GI/hepatology consult or infectious disease consult.
  • Consider referral for a liver transplant evaluation. [29]

Acute management checklist

Differential diagnoses

Secondary bacterial peritonitis [12][2][10]

Secondary bacterial peritonitis usually requires imaging and urgent surgical management.


The differential diagnoses listed here are not exhaustive.


We list the most important complications. The selection is not exhaustive.


Prophylaxis for SBP [2][10]

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last updated 11/02/2020
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