When to Give Prophylactic Antibiotics in Ascites
Prophylactic antibiotics should be given to patients with ascites in three specific clinical scenarios: (1) after recovery from an episode of spontaneous bacterial peritonitis (secondary prophylaxis), (2) in patients with acute gastrointestinal bleeding, and (3) in high-risk patients with low ascitic fluid protein (<1.5 g/dL) combined with advanced liver disease or renal impairment (primary prophylaxis). 1
Secondary Prophylaxis (After Prior SBP Episode)
All patients who survive an episode of SBP must receive indefinite antibiotic prophylaxis until liver transplantation or death. 1
- The recurrence rate without prophylaxis is approximately 70% at one year, and one-year survival after SBP is only 30-50% 1, 2
- Norfloxacin 400 mg once daily is the first-line agent, reducing SBP recurrence from 68% to 20% 1, 3
- Alternative regimens include ciprofloxacin 500 mg once daily or trimethoprim-sulfamethoxazole (800 mg/160 mg daily) 1, 3
- Rifaximin 550 mg twice daily is superior to norfloxacin for secondary prophylaxis, with a 6-month SBP recurrence rate of 4% versus 14% for norfloxacin, and should be considered when available 1, 4
Prophylaxis During Gastrointestinal Bleeding
All cirrhotic patients with acute upper gastrointestinal hemorrhage require short-term antibiotic prophylaxis (5-7 days). 1
- IV ceftriaxone 1 gram daily is the preferred agent for patients with advanced liver disease, administered until hemorrhage resolves and vasoactive drugs are discontinued 1, 3
- Oral norfloxacin 400 mg twice daily for 7 days is an alternative for patients with less severe liver disease 1
- Ceftriaxone is preferred over quinolones due to emergence of quinolone-resistant organisms 1
- Rule out active SBP before starting prophylaxis 1
Primary Prophylaxis (High-Risk Patients Without Prior SBP)
Antibiotic prophylaxis should be considered in patients with low ascitic fluid protein (<1.5 g/dL) PLUS at least one of the following high-risk features: 1
Specific High-Risk Criteria:
- Advanced liver failure: Child-Pugh score ≥9 points with serum bilirubin ≥3 mg/dL 1
- Impaired renal function: Serum creatinine ≥1.2 mg/dL, blood urea nitrogen ≥25 mg/dL, or serum sodium ≤130 mEq/L 1
Evidence for Primary Prophylaxis:
- In patients meeting these criteria, norfloxacin reduced the 1-year probability of first SBP from 60% to 7% 1
- Norfloxacin also reduced the incidence of hepatorenal syndrome (28% vs 41%) 1
- Three-month survival improved from 62% to 94% with prophylaxis 1
Recommended Regimen:
- Norfloxacin 400 mg once daily is the standard regimen 1
- Continue indefinitely until liver transplantation or resolution of high-risk features 1
Important Caveats and Pitfalls
Antibiotic Resistance Concerns:
- Long-term quinolone prophylaxis increases risk of quinolone-resistant gram-negative infections and gram-positive infections (including MRSA) 1, 2
- Consider local resistance patterns when selecting prophylactic antibiotics 3, 2
- Avoid quinolones as empiric treatment for suspected SBP in patients already on quinolone prophylaxis 3
When NOT to Use Primary Prophylaxis:
- Do not use prophylaxis indiscriminately in all patients with ascites—reserve only for those at highest risk 1
- Patients with ascitic fluid protein <1.5 g/dL but WITHOUT advanced liver disease or renal impairment have a lower risk (20% at one year) and prophylaxis is not routinely recommended 1
Monitoring Requirements:
- Perform diagnostic paracentesis if clinical deterioration occurs despite prophylaxis 2, 5
- Monitor for quinolone-associated tendon complications, especially with renal impairment 2, 5
- Regular renal function monitoring is recommended 5