📋 Key Information Summary
- Definition: Spontaneous infection of ascitic fluid in the absence of a contiguous source of infection, occurring in patients with advanced cirrhosis.
- Diagnostic Gold Standard: Ascitic fluid absolute neutrophil count (ANC) ≥250 cells/mm³. A positive ascitic fluid culture is supportive but not required for diagnosis.
- Culture Yield: Cultures are frequently negative. Inoculation of ascitic fluid into blood-culture bottles at the bedside significantly improves diagnostic yield.
- Key Variants: Culture-Negative Neutrocytic Ascites (CNNA; ANC ≥250, negative culture) is treated as SBP. Bacterascites (positive culture, ANC <250) is treated only if symptomatic.
- Rule Out Secondary Peritonitis: Essential. Suspect if ascitic fluid protein >10 g/L, glucose <2.8 mmol/L, or LDH > upper limit of serum normal (Runyon criteria). Requires urgent imaging to identify a surgically treatable source.
- Empirical Antibiotic Therapy: Immediate initiation of IV third-generation cephalosporin (cefotaxime or ceftriaxone) is first-line for community-acquired SBP.
- Healthcare/Nosocomial SBP: For nosocomial or healthcare-associated infections, use broader cover (e.g., piperacillin-tazobactam or a carbapenem) due to high MDRO risk, then de-escalate per culture results.
- Albumin Infusion: Mandatory adjunctive therapy. Dose: 1.5 g/kg on Day 1 and 1 g/kg on Day 3. Significantly reduces hepatorenal syndrome (HRS) and mortality, especially if serum creatinine >1 mg/dL (88 µmol/L) or bilirubin >68 µmol/L.
- Treatment Duration: 5 days of IV antibiotics is typically sufficient for uncomplicated SBP. Longer courses are not superior.
- Secondary Prophylaxis: Lifelong (until transplant) oral antibiotic prophylaxis (e.g., norfloxacin, ciprofloxacin, or TMP-SMX) is mandatory after an episode of SBP to prevent recurrence (~70% risk at 1 year).
- Primary Prophylaxis in GI Bleed: All cirrhotic patients with acute upper GI bleeding require IV antibiotics (ceftriaxone preferred for 7 days) to prevent SBP and other infections.
- Primary Prophylaxis in High-Risk Patients: Consider long-term prophylaxis in patients with low ascitic protein (<15 g/L) and advanced cirrhosis (Child-Pugh ≥9 with bilirubin ≥3 mg/dL) or renal dysfunction (Cr ≥1.2 mg/dL, Na ≤130 mmol/L).
- MDRO Consideration: Prophylactic antibiotics increase the risk of selecting for multidrug-resistant organisms (MDRO), which complicates future treatment episodes.
Diagnosis
A high index of clinical suspicion is required for diagnosis in any patient with cirrhosis and ascites who presents with fever, abdominal pain, worsening encephalopathy, or unexplained clinical deterioration. Diagnosis is based on analysis of a diagnostic paracentesis.
Ascitic Fluid Analysis
| Parameter | Diagnostic Criterion | Notes |
|---|---|---|
| Absolute Neutrophil Count (ANC) | ≥ 250 cells/mm³ | The cornerstone of diagnosis. Calculated from total WBC and differential. A manual differential is preferred if the automated count is abnormal. |
| Culture | Ideally positive, but not required | Yield is increased by inoculating 10–20 mL of ascitic fluid directly into both aerobic and anaerobic blood-culture bottles at the bedside. Monomicrobial growth is typical. |
| Total Protein, Glucose, LDH | Assess Runyon Criteria | See below for distinguishing SBP from secondary peritonitis. |
Diagnostic Variants
1
Culture-Negative Neutrocytic Ascites (CNNA)
ANC ≥250 cells/mm³ with a negative ascitic fluid culture (obtained via bedside blood-culture bottle inoculation). This is considered a variant of SBP and must be treated identically with empirical antibiotics.
2
Bacterascites
Positive ascitic fluid culture with an ANC <250 cells/mm³. Represents bacterial colonisation. Treatment is reserved for patients with signs or symptoms of infection (e.g., fever, abdominal pain).
Critical Step: Rule Out Secondary Peritonitis. A perforated viscus or abscess requires urgent surgical intervention. Suspect secondary peritonitis if any of the following (Runyon criteria) are present: Ascitic fluid total protein >10 g/L, glucose <2.8 mmol/L, or LDH > the upper limit of normal for serum. If any are met, obtain urgent CT abdomen/pelvis with contrast and consider surgical consultation.
Supportive Investigations
ESSENTIAL
Diagnostic Paracentesis
Perform immediately on admission for any cirrhotic patient with ascites, and always if SBP is suspected. Send for cell count, differential, culture (bedside bottles), total protein, glucose, LDH, albumin.
AVAILABLE
Blood Cultures (2 sets)
Should be drawn simultaneously, as bacteraemia accompanies SBP in up to 40% of cases.
AVAILABLE
Full Blood Examination, CRP, Liver & Renal Function, Coagulation
Assess for systemic inflammatory response, severity of liver disease (Child-Pugh, MELD), and renal function (creatinine) which guides albumin therapy and prognosis.
REFERRAL
CT Abdomen/Pelvis with IV Contrast
Mandatory if secondary peritonitis is suspected based on fluid analysis or clinical course. To identify perforation, abscess, or other intra-abdominal source.
Treatment
Treatment must be initiated immediately upon suspicion or diagnosis, without awaiting culture results. It comprises empirical antibiotic therapy and adjunctive intravenous albumin.
Empirical Antibiotic Therapy
The choice depends on the likely source and setting of infection (community vs. healthcare-associated).
Cefotaxime
Claforan® · Third-generation cephalosporin
Adult Dose
2 g IV every 8 hours. Extend to every 6 hours if severe sepsis.
Paediatric Dose
50 mg/kg/dose IV every 8 hours (max 2 g/dose).
Renal Adjustment
No adjustment required.
PBS Status
✔ PBS General Benefit
Ceftriaxone
Rocephin® · Third-generation cephalosporin
Adult Dose
2 g IV once daily.
Paediatric Dose
50–75 mg/kg/dose IV once daily (max 4 g/day).
Renal Adjustment
No adjustment required.
PBS Status
✔ PBS General Benefit
Healthcare/Nosocomial SBP: For infections developing >48h after hospital admission, or in patients with recent healthcare exposure (e.g., recent hospitalisation, haemodialysis, residence in a long-term care facility), use broader-spectrum cover to account for MDROs (ESBL-producing Enterobacterales, Pseudomonas, VRE). First-line: Piperacillin-tazobactam 4.5 g IV every 8 hours or a carbapenem (e.g., meropenem 1 g IV every 8 hours). Narrow spectrum based on final culture and sensitivity results.
Adjunctive Albumin Infusion
Strong Evidence-Based Recommendation: Intravenous albumin reduces the incidence of hepatorenal syndrome (HRS) and in-hospital mortality. It is indicated in all patients with SBP, with greatest benefit in those with at least one of: serum creatinine >1 mg/dL (88 µmol/L), blood urea nitrogen >30 mg/dL (10.7 mmol/L), or total bilirubin >4 mg/dL (68 µmol/L).
D1
Day 1
20% Albumin solution at a dose of 1.5 g/kg body weight. Maximum single dose is typically 100–125 g.
D3
Day 3
20% Albumin solution at a dose of 1 g/kg body weight. Monitor for signs of volume overload.
Monitoring & Duration
- Repeat Paracentesis: Not routinely required if clinical improvement. Consider at 48 hours if no clinical improvement (persistent fever, no reduction in abdominal pain) to confirm a falling ANC and rule out secondary peritonitis.
- Treatment Duration: A 5-day course of IV antibiotics is standard and sufficient for uncomplicated SBP. Longer courses (e.g., 10–14 days) do not improve outcomes and increase MDRO risk.
- Clinical Response: Expect clinical improvement (resolution of fever, reduced pain) within 48–72 hours. Failure to improve should prompt a reassessment of diagnosis and consideration of resistant organisms or secondary peritonitis.
Prophylaxis
Antibiotic prophylaxis is a critical component of SBP management, aimed at preventing first episodes (primary prophylaxis) and recurrence (secondary prophylaxis). The decision to use prophylaxis must balance the significant risk of MDRO selection.
Secondary Prophylaxis (Post-SBP)
Indicated for all patients who have survived an episode of SBP, as the 1-year recurrence rate is approximately 70%.
Norfloxacin
Generic · Fluoroquinolone
Prophylactic Dose
400 mg orally once daily.
Duration
Lifelong, or until liver transplant.
PBS Status
✔ PBS General Benefit
Ciprofloxacin
Ciproxin® · Fluoroquinolone (alternative)
Prophylactic Dose
500 mg orally once daily or 750 mg once weekly.
Duration
Lifelong, or until liver transplant.
PBS Status
✔ PBS General Benefit
Trimethoprim-Sulfamethoxazole (TMP-SMX)
Resprim® · Alternative if quinolone-resistant
Prophylactic Dose
1 double-strength tablet (160/800 mg) orally once daily.
PBS Status
✔ PBS General Benefit
Primary Prophylaxis: GI Bleed
All cirrhotic patients with acute upper gastrointestinal haemorrhage are at very high risk of developing SBP (and other bacterial infections). Prophylactic IV antibiotics should be initiated immediately at presentation and continued for 7 days.
Ceftriaxone
Preferred agent for GI bleed prophylaxis
Prophylactic Dose
1 g IV once daily for 7 days.
Rationale
Superior to oral norfloxacin in patients with advanced cirrhosis, particularly in areas with quinolone resistance.
Primary Prophylaxis in High-Risk Outpatients
Consider long-term oral prophylaxis in selected outpatients with cirrhosis who are at particularly high risk for a first episode of SBP. This is an area of active research and requires careful patient selection.
Consider
High-Risk Profile
Ascitic fluid total protein <15 g/L AND at least one of:
- Child-Pugh score ≥9 with serum bilirubin ≥3 mg/dL (51 µmol/L)
- Serum creatinine ≥1.2 mg/dL (106 µmol/L)
- Serum sodium ≤130 mmol/L
- Child-Pugh score ≥9 with serum bilirubin ≥3 mg/dL (51 µmol/L)
- Serum creatinine ≥1.2 mg/dL (106 µmol/L)
- Serum sodium ≤130 mmol/L
Agent: Norfloxacin 400 mg PO daily
MDRO Selection Pressure: The widespread use of fluoroquinolone prophylaxis is a major driver of infections caused by MDROs, including quinolone-resistant E. coli and ESBL-producing organisms. This complicates subsequent treatment of SBP and other infections. The decision for primary prophylaxis must be individualised and reviewed regularly.
Aboriginal and Torres Strait Islander Health
Considerations for Aboriginal and Torres Strait Islander Peoples
📚 References
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- 2. European Association for the Study of the Liver. EASL Clinical Practice Guidelines on the management of ascites, spontaneous bacterial peritonitis, and hepatorenal syndrome in cirrhosis. J Hepatol. 2010;53(3):397-417.
- 3. Biggins SW, Angeli P, Garcia-Tsao G, et al. Diagnosis, Evaluation, and Management of Ascites, Spontaneous Bacterial Peritonitis and Hepatorenal Syndrome: 2021 Practice Guidance by the American Association for the Study of Liver Diseases. Hepatology. 2021;74(2):1014-1048.
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- 8. Bernard B, Grangé JD, Khac EN, et al. Antibiotic prophylaxis for the prevention of bacterial infections in cirrhotic patients with gastrointestinal bleeding: a meta-analysis. Hepatology. 1999;29(6):1655-1661.
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- 11. Australian Institute of Health and Welfare (AIHW). Aboriginal and Torres Strait Islander Health Performance Framework 2020 summary report. Canberra: AIHW; 2020.
- 12. RHDAustralia (Rheumatic Heart Disease Australia). The 2020 Australian guideline for prevention, diagnosis and management of acute rheumatic fever and rheumatic heart disease (3rd edition). 2020. [Relevant for comorbid conditions and antibiotic prophylaxis principles].