SBP is a bacterial infection of ascitic fluid without an identifiable intra-abdominal surgically treatable source, occurring predominantly in patients with decompensated cirrhosis and ascites. In-hospital mortality remains approximately 20% despite advances in management. [1-2] Diagnostic paracentesis with ascitic fluid PMN count ≥250 cells/mm³ is the diagnostic standard, and treatment centers on IV third-generation cephalosporins plus IV albumin. [3-4]
1. History
- Known liver disease/cirrhosis, alcohol use, viral hepatitis, prior SBP episodes
- Abdominal pain — diffuse, often insidious; may be absent in up to one-third of patients [3]
- Fever, chills, nausea, vomiting, diarrhea, worsening abdominal distension
- New or worsening altered mental status/encephalopathy — may be the sole presenting complaint [2]
- Decreased urine output (AKI as a presenting feature)
- Timing: acute onset vs. gradual; recent hospitalization, procedures, or antibiotic exposure (community-acquired vs. nosocomial) [3]
- Ask about PPI use, beta-blocker therapy, recent GI bleeding, prior paracentesis [2][5]
2. Alarm Features
- Septic shock / hemodynamic instability — mortality increases 10% for every hour delay in antibiotics [3]
- New-onset or worsening hepatic encephalopathy [2]
- Acute kidney injury (rising creatinine, oliguria) — strongest predictor of death in SBP [6]
- Rebound tenderness, rigidity (consider secondary peritonitis) [7]
- Polymicrobial cultures, ascitic fluid glucose <50 mg/dL, LDH > upper limit of normal, protein >1 g/dL — suggest secondary peritonitis requiring surgical evaluation [7]
- GI hemorrhage concurrent with SBP
3. Medications
Treatment:
- Community-acquired SBP: IV cefotaxime 2 g q8h or ceftriaxone 2 g q24h for 5–7 days [3][8]
- Nosocomial/healthcare-associated SBP or sepsis: Piperacillin-tazobactam, meropenem ± vancomycin/daptomycin based on local resistance patterns and MRSA/VRE risk [3][9-10]
- IV albumin: 1.5 g/kg on day 1, 1 g/kg on day 3 (25% albumin) — reduces AKI and mortality [3][6][9]
Prophylaxis:
- Secondary: Norfloxacin 400 mg/day (or ciprofloxacin 500 mg/day, or TMP-SMX DS daily) until transplant, death, or resolution of ascites [3]
- Primary (GI bleed): IV ceftriaxone 1 g q24h for up to 7 days [3]
- Primary (high-risk): Consider in patients with ascitic protein <1.5 g/dL AND (Cr ≥1.2, BUN ≥25, Na ≤130, or CTP ≥9 with bilirubin ≥3) [2-3]
Medications to hold/avoid:
- NSBBs — hold if MAP <65 mmHg or AKI develops during SBP [3]
- PPIs — avoid unless clearly indicated; increase infection risk [2][11]
- Nephrotoxic agents (NSAIDs, aminoglycosides, IV contrast) [12]
4. Diet
- Sodium restriction (≤2 g/day) for ascites management
- Adequate protein intake (1.2–1.5 g/kg/day) to prevent sarcopenia — malnutrition worsens immune dysfunction [5]
- Avoid alcohol completely
- Ensure adequate hydration but avoid free water excess (risk of hyponatremia)
5. Review of Systems
- GI: Abdominal pain, distension, nausea, vomiting, diarrhea, GI bleeding (melena/hematemesis)
- Neuro: Confusion, somnolence, asterixis (encephalopathy)
- Renal: Decreased urine output, dark urine
- Constitutional: Fever, chills, malaise, weight gain (fluid)
- Respiratory: Dyspnea (hepatic hydrothorax, pulmonary edema from albumin)
- Skin: Jaundice, bruising, spider angiomata
6. Collateral History and Family History
- Confirm alcohol use history, medication compliance (diuretics, lactulose, SBP prophylaxis)
- Prior episodes of SBP, hospitalizations, recent antibiotic exposure (critical for empiric antibiotic selection) [3]
- Baseline mental status from family/caregivers (to assess encephalopathy)
- Family history of liver disease, hemochromatosis (increased risk of specific infections including Vibrio, Yersinia, Listeria) [2]
- Social context: housing stability, ability to follow up, transplant candidacy
7. Risk Factors
- Prior SBP episode — 1-year recurrence ~68% without prophylaxis [3]
- Low ascitic fluid protein (<1.5 g/dL) — decreased opsonic activity [3]
- Advanced cirrhosis (Child-Pugh C, high MELD) [2]
- GI hemorrhage [2]
- Renal dysfunction (Cr ≥1.2, BUN ≥25) or hyponatremia (Na ≤130) [3]
- PPI use, chronic antibiotic exposure, repeated hospitalizations [2]
- Malnutrition, sarcopenia, vitamin D deficiency [5]
- Bacterial translocation from gut dysbiosis — the central pathogenic mechanism [2]
8. Differential Diagnosis
- Secondary bacterial peritonitis — polymicrobial cultures, ascitic glucose <50, LDH elevated, protein >1 g/dL; requires CT and surgical evaluation [7][13]
- Peritoneal carcinomatosis — elevated ascitic protein, cytology positive, low SAAG
- Tuberculous peritonitis — lymphocyte-predominant ascites, elevated ADA, peritoneal biopsy
- Pancreatic ascites — elevated amylase in ascitic fluid
- Hepatic encephalopathy from other precipitants (GI bleed, constipation, medications) without SBP
- Spontaneous fungal peritonitis — suspect in culture-negative cases with renal insufficiency and multiple antibiotic courses [2]
- Chylous ascites — milky fluid, elevated triglycerides
9. Past Medical History
- Cirrhosis etiology (alcohol, viral hepatitis, NASH, autoimmune)
- Prior SBP episodes and causative organisms
- History of variceal bleeding, hepatic encephalopathy, HRS
- Transplant candidacy/listing status
- Diabetes (worsens immune dysfunction) [2]
- Chronic kidney disease
- Prior abdominal surgeries (relevant for secondary peritonitis)
10. Physical Exam
Vital signs:
Abdominal exam:
- Distension, shifting dullness, fluid wave
- Diffuse tenderness ± rebound (but may be absent in ~1/3) [3]
- Ileus (decreased/absent bowel sounds)
Stigmata of chronic liver disease:
Other:
- Asterixis, altered mental status (encephalopathy)
- Peripheral edema, muscle wasting
- Skin examination for cellulitis or other infection sources [3]
11. Lab Studies
Ascitic fluid (diagnostic paracentesis):
- Cell count with differential — PMN ≥250/mm³ = diagnostic of SBP [3]
- Culture — inoculate ≥10 mL into blood culture bottles at bedside (sensitivity >90%) [3][13]
- Total protein, albumin (calculate SAAG), glucose, LDH (to rule out secondary peritonitis) [7][13]
- In hemorrhagic ascites (RBC >10,000/mm³): subtract 1 PMN per 250 RBCs [14]
Serum labs:
- CBC with differential, CMP (Cr, BUN, electrolytes, LFTs, bilirubin, albumin)
- INR/PT — coagulopathy expected; routine transfusion NOT recommended prior to paracentesis [4]
- Lactate, blood cultures (2–3 sets) [3][13]
- Blood gas if septic
Monitoring:
- Serial creatinine (AKI surveillance)
- Repeat paracentesis at 48 hours if no clinical improvement — PMN decrease <25% from baseline = treatment failure [3]
12. Imaging
- Bedside ultrasound — identify ascites pocket, guide paracentesis, assess for loculations [4]
- Abdominal CT with contrast — indicated if secondary peritonitis suspected (failure to respond to antibiotics at 48h, polymicrobial cultures, Runyon criteria met) [3][7]
- Chest X-ray — rule out pneumonia, assess for hepatic hydrothorax [3]
- Routine imaging is not required for straightforward SBP diagnosis — paracentesis is the gold standard
13. Special Tests
- Leukocyte esterase reagent strips on ascitic fluid — can provide rapid bedside diagnosis if available (sensitivity ~90% at grade 3+ for PMN ≥250) [4]
- SAAG (serum-albumin ascites gradient) — ≥1.1 g/dL confirms portal hypertension
- Ascitic fluid pH <7.35 increases likelihood of SBP (summary LR 9.0) [15]
- MELD score — severity stratification and prognostication; SBP resolution is a significant factor for survival [8]
- Child-Turcotte-Pugh score — guides prophylaxis decisions [3]
14. ECG
- Obtain ECG in patients with hemodynamic instability or sepsis
- Assess for QTc prolongation (common in cirrhosis; worsened by electrolyte abnormalities and certain antibiotics like fluoroquinolones)
- Rule out arrhythmias in the setting of electrolyte derangements (hypokalemia, hypomagnesemia)
- Cirrhotic cardiomyopathy may manifest with conduction abnormalities
15. Assessment
SBP occurs in 7–31% of hospitalized cirrhotic patients with ascites. [5] It is most commonly caused by gram-negative bacteria (~60%, predominantly E. coli and Klebsiella), though gram-positive organisms (Staphylococcus, Enterococcus) and MDR organisms are increasing, particularly in nosocomial settings. [3][9] The pathogenesis involves bacterial translocation from the gut in the setting of cirrhosis-associated immune dysfunction, portal hypertension, and altered intestinal permeability. [2]
The following figure illustrates the pathogenesis of SBP:
Key prognostic considerations:
- In-hospital mortality ~20% [1]
- AKI at diagnosis is the strongest predictor of death [6]
- Bacterial infections increase mortality 4-fold in cirrhosis [1]
- SBP is a major trigger of acute-on-chronic liver failure (ACLF) [1]
16. Treatment Plan
Initial stabilization:
- IV access, fluid resuscitation with caution (avoid crystalloid overload), vasopressors if septic shock
- Diagnostic paracentesis immediately — do not delay for coagulopathy correction [4]
Antibiotics (start empirically once PMN ≥250/mm³):
- Duration: 5–7 days; may shorten if PMN drops to <250/mm³ [3]
- Narrow antibiotics once culture/sensitivity available [3]
Albumin:
- 1.5 g/kg IV on day 1, 1 g/kg IV on day 3 (25% albumin) [3][6]
- Reduces AKI from 33% to 10% and mortality from 29% to 10% [6]
- Greatest benefit in patients with bilirubin >4 mg/dL or baseline AKI [3][6]
- Monitor for pulmonary edema [6]
Response assessment:
17. Disposition
Admit all patients with SBP — this is an inpatient diagnosis requiring IV antibiotics and albumin. [3-4]
- ICU admission: Septic shock, vasopressor requirement, multiorgan failure, ACLF, need for intubation
- Floor/step-down: Hemodynamically stable SBP without organ failure
- Hepatology/GI consultation for all cases; transplant evaluation if not already listed
- Surgery consultation if secondary peritonitis suspected [7]
- Infectious disease consultation for MDR organisms or treatment failure
18. Follow Up / Return Precautions
Inpatient:
- Monitor creatinine, electrolytes, mental status daily
- Reassess at 48 hours with repeat paracentesis if not clinically improving [3]
At discharge:
- Start secondary SBP prophylaxis — norfloxacin 400 mg/day, ciprofloxacin 500 mg/day, or TMP-SMX DS daily [3]
- Continue until transplant, death, or resolution of ascites
- Transplant referral — SBP is a marker of advanced disease and an indication for transplant evaluation [1]
- Discontinue PPIs unless clearly indicated [11]
Return precautions — counsel patients to return immediately for:
- Fever, chills, worsening abdominal pain or distension
- Confusion, drowsiness, or behavioral changes
- Decreased urine output
- Blood in stool or vomiting blood
- Inability to take oral medications
Expected course:
- Clinical improvement typically within 48–72 hours
- 1-year recurrence without prophylaxis: ~68%; with prophylaxis: ~20% [3]
- 1-year mortality after first SBP episode is high — underscores the importance of transplant evaluation
References
1. Liver Cirrhosis. — Ginès P, Krag A, Abraldes JG, et al. Lancet. 2021.
2. Liver Cirrhosis. — Ginès P, Krag A, Abraldes JG, et al. Lancet. 2021.
3. Liver Cirrhosis. — Ginès P, Krag A, Abraldes JG, et al. Lancet. 2021.
4. The Evolving Challenge of Infections in Cirrhosis. — Bajaj JS, Kamath PS, Reddy KR. The New England Journal of Medicine. 2021.
5. The Evolving Challenge of Infections in Cirrhosis. — Bajaj JS, Kamath PS, Reddy KR. The New England Journal of Medicine. 2021.
6. 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. — Biggins SW, Angeli P, Garcia-Tsao G, et al. Hepatology. 2021.
7. 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. — Biggins SW, Angeli P, Garcia-Tsao G, et al. Hepatology. 2021.
8. Emergency Medicine Updates: Spontaneous Bacterial Peritonitis. — Long B, Gottlieb M. The American Journal of Emergency Medicine. 2023.
9. Emergency Medicine Updates: Spontaneous Bacterial Peritonitis. — Long B, Gottlieb M. The American Journal of Emergency Medicine. 2023.
10. Review article: spontaneous bacterial peritonitis – bacteriology, diagnosis, treatment, risk factors and prevention. — Dever JB, Sheikh MY. Alimentary Pharmacology & Therapeutics. 2015.
11. Review article: spontaneous bacterial peritonitis – bacteriology, diagnosis, treatment, risk factors and prevention. — Dever JB, Sheikh MY. Alimentary Pharmacology & Therapeutics. 2015.
12. AGA Clinical Practice Update on the Use of Vasoactive Drugs and Intravenous Albumin in Cirrhosis: Expert Review. — Garcia-Tsao G, Abraldes JG, Rich NE, Wong VW. Gastroenterology. 2024.
13. AGA Clinical Practice Update on the Use of Vasoactive Drugs and Intravenous Albumin in Cirrhosis: Expert Review. — Garcia-Tsao G, Abraldes JG, Rich NE, Wong VW. Gastroenterology. 2024.
14. Utility of an Algorithm in Differentiating Spontaneous From Secondary Bacterial Peritonitis. — Akriviadis EA, Runyon BA. Gastroenterology. 1990.
15. Utility of an Algorithm in Differentiating Spontaneous From Secondary Bacterial Peritonitis. — Akriviadis EA, Runyon BA. Gastroenterology. 1990.
16. Response-Guided Therapy With Cefotaxime, Ceftriaxone, or Ciprofloxacin for Spontaneous Bacterial Peritonitis: A Randomized Trial: A Validation Study of 2021 AASLD Practice Guidance for SBP. — Yim HJ, Kim TH, Suh SJ, et al. The American Journal of Gastroenterology. 2023.
17. Response-Guided Therapy With Cefotaxime, Ceftriaxone, or Ciprofloxacin for Spontaneous Bacterial Peritonitis: A Randomized Trial: A Validation Study of 2021 AASLD Practice Guidance for SBP. — Yim HJ, Kim TH, Suh SJ, et al. The American Journal of Gastroenterology. 2023.
18. Guidelines for the Management of Adult Acute and Acute-on-Chronic Liver Failure in the ICU: Neurology, Peri-Transplant Medicine, Infectious Disease, and Gastroenterology Considerations. — Nanchal R, Subramanian R, Alhazzani W, et al. Critical Care Medicine. 2023.
19. Guidelines for the Management of Adult Acute and Acute-on-Chronic Liver Failure in the ICU: Neurology, Peri-Transplant Medicine, Infectious Disease, and Gastroenterology Considerations. — Nanchal R, Subramanian R, Alhazzani W, et al. Critical Care Medicine. 2023.
20. Infections in Cirrhosis. — Piano S, Bunchorntavakul C, Marciano S, Rajender Reddy K. The Lancet. Gastroenterology & Hepatology. 2024.
21. Infections in Cirrhosis. — Piano S, Bunchorntavakul C, Marciano S, Rajender Reddy K. The Lancet. Gastroenterology & Hepatology. 2024.
22. Acute-on-Chronic Liver Failure Clinical Guidelines. — Bajaj JS, O'Leary JG, Lai JC, et al. The American Journal of Gastroenterology. 2022.
23. Acute-on-Chronic Liver Failure Clinical Guidelines. — Bajaj JS, O'Leary JG, Lai JC, et al. The American Journal of Gastroenterology. 2022.
24. AASLD Practice Guidance on Acute-on-Chronic Liver Failure and the Management of Critically Ill Patients With Cirrhosis. — Karvellas CJ, Bajaj JS, Kamath PS, et al. Hepatology. 2024.
25. AASLD Practice Guidance on Acute-on-Chronic Liver Failure and the Management of Critically Ill Patients With Cirrhosis. — Karvellas CJ, Bajaj JS, Kamath PS, et al. Hepatology. 2024.
26. Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases: 2024 Update by the Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM). — Miller JM, Binnicker MJ, Campbell S, et al. Clinical Infectious Diseases : An Official Publication of the Infectious Diseases Society of America. 2024.
27. Guide to Utilization of the Microbiology Laboratory for Diagnosis of Infectious Diseases: 2024 Update by the Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM). — Miller JM, Binnicker MJ, Campbell S, et al. Clinical Infectious Diseases : An Official Publication of the Infectious Diseases Society of America. 2024.
28. Antibiotic Prophylaxis to Prevent Spontaneous Bacterial Peritonitis in People With Liver Cirrhosis: A Network Meta-Analysis. — Komolafe O, Roberts D, Freeman SC, et al. The Cochrane Database of Systematic Reviews. 2020.
29. Antibiotic Prophylaxis to Prevent Spontaneous Bacterial Peritonitis in People With Liver Cirrhosis: A Network Meta-Analysis. — Komolafe O, Roberts D, Freeman SC, et al. The Cochrane Database of Systematic Reviews. 2020.
30. Does This Patient Have Bacterial Peritonitis or Portal Hypertension? How Do I Perform a Paracentesis and Analyze the Results?. — Wong CL, Holroyd-Leduc J, Thorpe KE, Straus SE. The Journal of the American Medical Association. 2008.
31. Does This Patient Have Bacterial Peritonitis or Portal Hypertension? How Do I Perform a Paracentesis and Analyze the Results?. — Wong CL, Holroyd-Leduc J, Thorpe KE, Straus SE. The Journal of the American Medical Association. 2008.
32. Current Status and Prospects of Spontaneous Peritonitis in Patients with Cirrhosis. — Li YT, Huang JR, Peng ML. BioMed Research International. 2020.
33. Current Status and Prospects of Spontaneous Peritonitis in Patients with Cirrhosis. — Li YT, Huang JR, Peng ML. BioMed Research International. 2020.