Management of Spontaneous Bacterial Peritonitis (SBP)

Diagnostic Criteria

The diagnosis of SBP is definitively established when the ascitic fluid neutrophil count exceeds 250 cells/mm³, as determined by microscopy or automated cell counting, in patients with cirrhosis and ascites 1, 2, 3
Diagnostic paracentesis should be performed in all cirrhotic patients with ascites at hospital admission, even without symptoms, to diagnose SBP, as recommended by the American Association for the Study of Liver Diseases and the European Association for the Study of the Liver 1, 2, 3
Additional indications for paracentesis in patients with known or suspected SBP include gastrointestinal bleeding, shock or signs of systemic inflammation, gastrointestinal symptoms, worsening liver or renal function, and hepatic encephalopathy 1, 3

Collect ascitic fluid via paracentesis, preferably from the left lower quadrant, 3 cm cephalad and medial to the anterior superior iliac spine, to diagnose SBP 4
Send samples for cell count with differential, culture, and total protein to identify SBP risk and differentiate from secondary peritonitis, as suggested by the American Association for the Study of Liver Diseases 1, 2, 4, 5
Simultaneously obtain blood cultures to guide antibiotic therapy in patients with SBP, as recommended by the European Association for the Study of the Liver 1, 2, 3
Bedside inoculation of ascitic fluid into blood culture bottles increases culture sensitivity to >80-90% for diagnosing SBP 1, 4

Initiate empiric antibiotic therapy immediately after diagnosis of SBP, with first-line therapy being third-generation cephalosporin (cefotaxime 2g IV every 8 hours), as recommended by the European Association for the Study of the Liver 3, 1, 4
Avoid potentially nephrotoxic antibiotics, and consider alternative regimens such as amoxicillin/clavulanic acid or oral ofloxacin for patients without vomiting, shock, or grade II+ hepatic encephalopathy, as suggested by the American Association for the Study of Liver Diseases 3, 1, 4
Duration of therapy: 5-day therapy is as effective as 10-day treatment, as recommended by the European Association for the Study of the Liver 3, 1
Consider prophylactic antibiotics (norfloxacin) for patients with previous episode of SBP, gastrointestinal bleeding, or low ascitic fluid protein (<1.5 g/dL), as suggested by the American Association for the Study of Liver Diseases 4, 5

Suspect secondary peritonitis when localized abdominal symptoms or signs are present, multiple organisms are seen on ascitic culture, very high ascitic neutrophil count, high ascitic protein concentration, or inadequate response to therapy, as recommended by the European Association for the Study of the Liver 3, 1
Perform appropriate radiological investigation, such as CT scan, and additional tests, such as ascitic fluid total protein and LDH, to diagnose secondary peritonitis 1
Additional tests to differentiate from SBP include ascitic fluid total protein >1 g/dL, LDH higher than upper limit of normal for serum, and glucose <50 mg/dL, as suggested by the American Association for the Study of Liver Diseases 4, 5

Delaying paracentesis increases mortality by 10% for every hour's delay in initiating antibiotics in patients with septic shock 2
Not sending cultures properly, such as bedside inoculation of at least 10 mL of ascitic fluid into blood culture bottles, reduces sensitivity to <90% for diagnosing SBP 2, 4
Missing asymptomatic SBP, which can occur in up to one-third of patients, can lead to delayed diagnosis and treatment 2
Follow-up paracentesis is not necessary in all patients with SBP, but consider repeat paracentesis in atypical presentation or clinical course, suspected secondary peritonitis, or inadequate response to therapy, as suggested by the American Association for the Study of Liver Diseases 4, 5