What is the treatment for spontaneous bacterial peritonitis?

Treatment of Spontaneous Bacterial Peritonitis

Third-generation cephalosporins are the first-line treatment for spontaneous bacterial peritonitis, with cefotaxime 2g IV every 6-8 hours or ceftriaxone 1-2g IV every 12-24 hours recommended for 5-10 days. 1

Diagnosis and Initial Management

• SBP is diagnosed when ascitic fluid polymorphonuclear leukocyte (PMN) count is >250/mm³, regardless of culture results
• Empirical antibiotic therapy should be started immediately after diagnosis, without waiting for culture results
• Even with PMN count <250/mm³, empirical antibiotics should be initiated if infection symptoms are present (fever >37.8°C, abdominal pain/tenderness) 1

Antibiotic Selection Algorithm

Community-acquired SBP:

1. First-line treatment:

   • Cefotaxime 2g IV every 6-8 hours OR
   • Ceftriaxone 1g IV every 12-24 hours
   • Duration: 5-10 days (5 days is as effective as 10 days in most cases) 1

2. Alternative options:

   • Amoxicillin-clavulanic acid (1g/0.2g IV every 8 hours, followed by 500mg/125mg PO every 8 hours)
   • Oral ofloxacin (400mg every 12 hours) - only for uncomplicated SBP without renal failure, hepatic encephalopathy, GI bleeding, ileus, or shock 1

Hospital-acquired SBP:

• Higher risk of treatment failure with third-generation cephalosporins due to resistant organisms
• Consider broader-spectrum antibiotics:
  • Meropenem (1g every 8 hours) + daptomycin (6mg/kg/day) - shown to be more effective than ceftazidime for nosocomial SBP 2
  • Piperacillin-tazobactam may be considered based on local resistance patterns 3

Treatment Response Monitoring

• A second paracentesis after 48 hours of treatment is recommended to assess response
• Treatment failure should be suspected if:
  • Ascitic fluid PMN count fails to decrease by at least 25% of pre-treatment value
  • Clinical signs and symptoms worsen
  • No marked reduction in ascitic fluid neutrophil count 1

Adjunctive Therapy

• Albumin administration: Cefotaxime plus IV albumin (1.5g/kg at diagnosis, followed by 1g/kg on day 3) significantly reduces mortality compared to cefotaxime alone (10% vs 29%, p=0.01) 1
• This combination decreases the risk of renal impairment and death, particularly in high-risk patients

Special Considerations

• For patients on quinolone prophylaxis who develop SBP, use cefotaxime or amoxicillin-clavulanic acid 1
• In areas with high quinolone resistance (>30%), avoid quinolones for empiric therapy 1
• Consider secondary bacterial peritonitis if:
  • PMN count >1,000/mm³
  • Multiple organisms on culture
  • Ascitic total protein ≥1g/dL
  • Ascitic glucose ≤50mg/dL
  • No improvement after 48 hours of antibiotics 1

Common Pitfalls to Avoid

• Delaying antibiotic initiation while waiting for culture results
• Using potentially nephrotoxic antibiotics (e.g., aminoglycosides)
• Failing to administer albumin in high-risk patients
• Not performing follow-up paracentesis to confirm treatment response
• Overlooking the possibility of secondary bacterial peritonitis when response is poor

The mortality from SBP has decreased significantly with prompt antibiotic therapy, but hospital mortality remains around 20-30% due to underlying severe liver disease and cytokine-mediated complications 4. Therefore, early and appropriate antibiotic therapy combined with albumin supplementation is crucial for improving outcomes.