Primary Prophylaxis for Spontaneous Bacterial Peritonitis (SBP)
For primary prophylaxis of SBP, norfloxacin 400 mg daily is recommended for high-risk cirrhotic patients with ascites who have low ascitic fluid protein (<15 g/L) combined with advanced liver disease or impaired renal function. 1
Patient Selection for Primary Prophylaxis
Primary prophylaxis should be targeted to specific high-risk patients:
- Patients with ascitic fluid protein <15 g/L (1.5 g/dL) AND one of the following 1:
- Child-Pugh score ≥9 with serum bilirubin ≥3 mg/dL, OR
- Impaired renal function (serum creatinine ≥1.2 mg/dL, BUN ≥25 mg/dL), OR
- Hyponatremia (serum sodium ≤130 mEq/L)
Recommended Antibiotic Regimens
- First choice: Norfloxacin 400 mg orally once daily 1, 2
- Alternative: Ciprofloxacin 500 mg orally once daily (especially in regions where norfloxacin availability is limited) 1, 3
- Duration: Until resolution of ascites or liver transplantation 1
Evidence Supporting Prophylaxis
Primary prophylaxis with norfloxacin has shown significant benefits:
- Reduces the one-year probability of developing SBP (7% vs. 61%) 1
- Improves three-month survival probability (94% vs. 62%) 1, 3
- Reduces the risk of hepatorenal syndrome (28% vs. 41%) 1
Important Considerations and Pitfalls
- Fluoroquinolones carry risks of side effects including tendon inflammation and damage, particularly in patients with renal impairment 1, 3
- Long-term antibiotic use can lead to bacterial resistance and increased risk of Clostridium difficile infection 1, 2
- The MHRA (UK) has issued warnings about fluoroquinolone side effects - discontinue at first sign of tendon pain or inflammation 1
- Consider restricting proton pump inhibitor use as they may increase SBP risk 1, 3
- Monitor for development of multidrug-resistant organisms, especially with prolonged use 1, 4
Alternative Approaches
- Recent research suggests rifaximin may be effective for primary prophylaxis with similar efficacy to norfloxacin 5, 6
- Weekly ciprofloxacin has been studied as an alternative to daily norfloxacin, but this regimen may increase the risk of developing resistant organisms 7, 6
- Trimethoprim-sulfamethoxazole (800/160 mg daily) is another alternative but may have more adverse events 3, 6
Special Situations
- All cirrhotic patients with gastrointestinal bleeding should receive antibiotic prophylaxis regardless of ascitic fluid protein levels 2, 4
- For patients with severe liver disease and GI bleeding, IV ceftriaxone 1g daily for 7 days is preferred 2, 4
- All patients receiving primary prophylaxis should be considered for liver transplantation evaluation due to poor long-term prognosis 2, 3