What is the treatment for spontaneous bacterial peritonitis?

Treatment for Spontaneous Bacterial Peritonitis

The first-line treatment for community-acquired spontaneous bacterial peritonitis (SBP) is intravenous third-generation cephalosporins, specifically cefotaxime 2g every 6-8 hours or ceftriaxone 1g every 12-24 hours for 5-7 days. 1

Diagnostic Criteria and Initial Management

• SBP is diagnosed when the polymorphonuclear leukocyte (PMN) count in ascitic fluid is >250/mm³, regardless of culture results 2
• Even with PMN <250/mm³, empirical antibiotics should be started if symptoms/signs of infection are present (fever >37.8°C, abdominal pain/tenderness) 2
• Empirical antibiotic therapy should begin immediately before culture results are available

Antibiotic Selection Algorithm

For Community-Acquired SBP:

1. First-line treatment:

   • Cefotaxime 2g IV every 6-8 hours OR
   • Ceftriaxone 1g IV every 12-24 hours 2, 1
   • Treatment duration: 5-7 days (can be extended based on clinical response)

2. Alternative options:

   • Amoxicillin-clavulanic acid 1g/0.2g IV every 8 hours 1
   • Oral ciprofloxacin 500mg every 12 hours (for uncomplicated cases without contraindications) 1, 3

For Hospital-Acquired (Nosocomial) SBP:

• Broader-spectrum antibiotics recommended due to higher resistance rates 1
• Consider meropenem plus daptomycin, which has shown superior efficacy (86.7% vs. 25%) compared to ceftazidime 4

Adjunctive Therapy

• Albumin administration: Critical for high-risk patients (serum bilirubin ≥4 mg/dL or serum creatinine ≥1 mg/dL)
  • Dosage: 1.5 g/kg at diagnosis and 1 g/kg on day 3 1
  • Reduces hepatorenal syndrome incidence and decreases mortality from 29% to 10% 1

Monitoring Treatment Response

1. Perform follow-up paracentesis after 48 hours of antibiotic therapy 1
2. Treatment success defined as:
   • Decrease in ascitic fluid neutrophil count to <250/mm³
   • Decrease of at least 25% from pre-treatment value
   • Sterile cultures
   • Clinical improvement 1

Management of Treatment Failure

If no improvement after 48 hours (persistent fever, worsening abdominal pain, or no decrease in PMN count by at least 25%):

1. Rule out secondary bacterial peritonitis
2. Adjust antibiotics based on culture results
3. Consider broader spectrum antibiotics like carbapenems (meropenem 1g IV every 8 hours) 1, 4

Differentiating Secondary Bacterial Peritonitis

Secondary bacterial peritonitis (from intestinal perforation or abscess) has a high mortality rate (50-80%) and requires surgical intervention. Suspect if:

1. PMN count >1,000/mm³
2. Multiple organisms on Gram stain or culture
3. Ascitic total protein ≥1 g/dL
4. LDH in ascites above normal upper limit of serum LDH
5. Ascitic glucose ≤50 mg/dL
6. PMN count doesn't drop after 48 hours of antibiotics
7. Elevated ascitic fluid CEA (>5 ng/mL) or alkaline phosphatase (>240 U/L) 2

If suspected, perform abdominal CT imaging promptly 2

Important Clinical Considerations

• Cefotaxime has been extensively studied with resolution rates of 69-98% 2, 5
• Lower doses of cefotaxime (2g every 12 hours) may be as effective as higher doses (2g every 6 hours) in some patients 6
• Ceftriaxone 2g daily may be associated with better outcomes than 1g daily, though this difference may be related to disease severity (MELD score) 7
• Quinolone resistance is increasing, making them less reliable in patients previously exposed to quinolones or with prior SBP 1
• Avoid aminoglycosides in patients with significant residual kidney function 1

The evidence strongly supports third-generation cephalosporins as first-line therapy for community-acquired SBP, with broader-spectrum antibiotics for nosocomial infections and albumin supplementation for high-risk patients to improve survival outcomes.