Spontaneous Bacterial Peritonitis and Secondary Bacterial Peritonitis Guidelines

Diagnostic Criteria

The European Association for the Study of the Liver defines Spontaneous Bacterial Peritonitis (SBP) as a bacterial infection of ascitic fluid without any intra-abdominal surgically treatable source of infection, with diagnosis based on an ascitic fluid polymorphonuclear (PMN) leukocyte count >250/mm³, regardless of culture results 1, 2, 3
SBP is typically a monomicrobial infection (single organism) 4
Ascitic fluid culture is positive in only about 50-80% of SBP cases (higher with bedside inoculation into blood culture bottles) 4
Secondary Bacterial Peritonitis often presents with localized abdominal symptoms or signs, multiple organisms typically seen on Gram stain or in culture, and a higher ascitic PMN count (often >1,000/mm³) 4, 5

The American Association for the Study of Liver Diseases recommends immediate empirical antibiotic therapy upon diagnosis of SBP, with first-line treatment being third-generation cephalosporins (e.g., cefotaxime 2g IV every 6-8 hours for 5 days) 3
Intravenous albumin (1.5 g/kg at diagnosis and 1 g/kg on day 3) significantly reduces risk of hepatorenal syndrome and mortality in SBP patients 3
Secondary Bacterial Peritonitis requires prompt surgical consultation and intervention, broader spectrum antibiotics, and surgical treatment of the underlying cause (e.g., perforation, abscess) 1, 4, 5

SBP may present with fever, abdominal pain, altered mental status, or worsening of liver function, while Secondary Bacterial Peritonitis often presents with localized abdominal pain and tenderness 1, 2, 4, 5
Delaying antibiotic therapy in suspected SBP increases mortality by approximately 10% for every hour's delay in patients with septic shock 3
Culture-negative neutrocytic ascites (PMN count ≥250/mm³ but negative culture) should be treated as SBP, and patients with cirrhosis and ascites should undergo diagnostic paracentesis at hospital admission to rule out SBP, even without symptoms suggestive of infection 1, 3, 4