Antibiotics for Prevention and Treatment of Spontaneous Bacterial Peritonitis
Treatment of Acute SBP
Third-generation cephalosporins, specifically cefotaxime (2g IV every 8-12 hours) or ceftriaxone (1-2g IV every 12-24 hours), are the first-line empirical antibiotics for community-acquired SBP and should be started immediately upon diagnosis. 1
First-Line Treatment Algorithm
Community-acquired SBP: Start cefotaxime 2g IV every 8-12 hours (4g/day is as effective as 8g/day) for 5-7 days 1, 2
Nosocomial or healthcare-associated SBP: Use broader-spectrum coverage with meropenem (1g IV every 8 hours) plus daptomycin (6mg/kg/day) in settings with high multidrug-resistant organism (MDRO) prevalence 1, 4
Alternative Antibiotic Options
Amoxicillin/clavulanic acid: 1g/0.2g IV every 8 hours, then switch to 0.5g/0.125g PO every 8 hours (87% resolution rate, similar to cefotaxime) 1, 3
Oral ofloxacin: 400mg PO every 12 hours for uncomplicated SBP only (without renal failure, hepatic encephalopathy, GI bleeding, ileus, or shock) 1
- Achieves 84% infection resolution, comparable to IV cefotaxime 1
Piperacillin/tazobactam: Effective for community-acquired and healthcare-associated SBP in areas with low MDRO prevalence 5
- Recommended by EASL as primary approach for healthcare-associated SBP in low-MDRO settings 5
Critical Caveats for Quinolone Use
Avoid quinolones (ciprofloxacin, ofloxacin) in three specific scenarios: 1
- Patients already on quinolone prophylaxis
- Areas with high quinolone-resistant bacteria prevalence
- Nosocomial SBP
Essential Adjunctive Therapy
Add IV albumin (1.5g/kg at diagnosis, then 1g/kg on day 3) to antibiotic therapy—this reduces hepatorenal syndrome from 30% to 10% and mortality from 29% to 10%. 1, 5, 3
- Most beneficial in patients with baseline bilirubin ≥68 μmol/L (4 mg/dL) or creatinine ≥88 μmol/L 1, 5
Monitoring Treatment Response
- Perform repeat paracentesis at 48 hours to assess neutrophil count 1, 5
- Treatment failure: Suspect if ascitic neutrophil count fails to decrease to <25% of pre-treatment value 1
- Resolution criteria: Ascitic neutrophil count <250/mm³ and sterile cultures 1, 5
Management of Treatment Failure
When clinical worsening occurs or neutrophil count doesn't decrease appropriately: 1
- Exclude secondary bacterial peritonitis (requires surgical intervention)
- Switch antibiotics based on culture sensitivities
- If cultures unavailable, broaden to carbapenems empirically 1
Prevention of SBP
Secondary Prophylaxis (After SBP Episode)
All patients surviving an SBP episode require indefinite long-term antibiotic prophylaxis until liver transplantation or death—norfloxacin 400mg PO daily is the standard regimen. 3
Primary Prophylaxis Indications
Norfloxacin 400mg PO daily for: 6, 7
- Low-protein ascites (ascitic fluid total protein <1g/dL) during hospitalization
- Cirrhotic patients with GI bleeding (400mg twice daily for 7 days) 6
- Severe ascites with advanced liver failure awaiting transplant 6
Important Prophylaxis Considerations
- Monitor for quinolone-resistant organism infections during long-term prophylaxis 7
- Trimethoprim-sulfamethoxazole may be superior due to gram-positive coverage 8
- Local resistance patterns should guide prophylaxis choice 5
Key Clinical Pitfalls
- Never delay antibiotics waiting for culture results—empirical therapy must start immediately upon diagnosis 1
- Avoid aminoglycosides (e.g., tobramycin) due to nephrotoxicity 1
- Don't forget albumin—antibiotics alone miss the mortality benefit 1
- Recognize the MDRO shift—nosocomial SBP now has 35% MDRO rate, requiring broader initial coverage 1
- Antibiotic stewardship—narrow coverage once cultures available and treat for shortest effective duration 1