Spontaneous bacterial peritonitis

SBP

Risk factors

• Nearly always an indicator of severe liver disease - mostly CP-C. Poor short and long-term prognosis.
• 30% of cirrhotic patients with ascites develop it

Pathophysiology

• An ascites fluid infection that occurs spontaneously without any overt source - probably mostly spreads from blood, or direct bacterial translocation through bowel. But the primary source is most likely GIT.
• Translocation may occur due to intestinal hypo-motility and increased permeability
• Can also occur with haematogenous spread from a non-GIT source
• Possible with only minimal ascites, although there is often large volume ascites

Bacteriology

• Most commonly E coli and Klebsiella pneumoniae
• 90% gram-negative enteric organisms

Presentation

• Can be asymptomatic initially
• Fever
• Abdominal pain
• Jaundice
• Confusion
• Peritonitis may be absent - as few as 10% have rebound tenderness at presentation

Diagnosis

• Clinical signs and symptoms are not sufficient - need paracentesis
• Ascitic fluid with neutrophil count > 250 cells/mm(3)
• Difficult to differentiate from secondary peritonitis - send ascitic sample for total protein, LDH and glucose.
• Features suggestive of secondary peritonitis:
  • Multiple organisms on culture
  • Very high ascitic neutrophil counts
  • Ascitic fluid total protein >1g/dL
  • Ascitic fluid LDH greater than half upper limit of serum
  • Ascitic fluid glucose < 50mg/dL
• If above features found:
  • CT - to look for perforation/abscess

Treatment

• Empiric Abx once sample taken
• IV albumin 1.5g/kg within 6 hours of SBP diagnosis and 1g/kg on day 3 if BUN < 30mg/dL, serum creatinine >1mg/dL, or total bilirubin < 4mg/dL

Prophylaxis

• Oral ciprofloxacin 750mg weekly