What are the indications and medications for primary and secondary prophylaxis of Spontaneous Bacterial Peritonitis (SBP)?

Indications and Medications for SBP Prophylaxis in Cirrhosis

Norfloxacin 400 mg daily is the first-line agent for secondary prophylaxis of SBP, while primary prophylaxis should be offered to high-risk patients with ascitic fluid protein <15 g/L combined with advanced liver disease or impaired renal function. 1

Primary Prophylaxis

Indications

• Patients with low ascitic fluid protein (<15 g/L) AND one of the following: 1, 2
  • Child-Pugh score ≥9 with serum bilirubin ≥3 mg/dL 1
  • Impaired renal function (serum creatinine ≥1.2 mg/dL, BUN ≥25 mg/dL) 1, 2
  • Hyponatremia (serum sodium ≤130 mEq/L) 1, 2

Medications

• First choice: Norfloxacin 400 mg orally once daily 1, 2
• Alternatives:
  • Ciprofloxacin 500 mg orally once daily 1, 2
  • Co-trimoxazole (800 mg sulfamethoxazole and 160 mg trimethoprim) orally once daily 1, 3

Efficacy

• Norfloxacin reduces one-year probability of developing SBP from 61% to 7% 1
• Three-month survival probability improves from 62% to 94% 1, 3
• Reduces risk of hepatorenal syndrome (28% vs 41%) 1

Secondary Prophylaxis

Indications

• All patients who have recovered from a previous episode of SBP 1, 3
  • Without prophylaxis, recurrence rate at 1 year is approximately 70% 1
  • One-year survival after SBP without prophylaxis is only 30-50% 1, 3

Medications

• First choice: Norfloxacin 400 mg orally once daily 1, 3
• Alternatives:
  • Ciprofloxacin 500 mg orally once daily 1, 3
  • Co-trimoxazole (800 mg sulfamethoxazole and 160 mg trimethoprim) orally once daily 1, 3
  • Rifaximin 550 mg twice daily (emerging evidence) 4

Efficacy

• Norfloxacin reduces probability of SBP recurrence from 68% to 20% 1, 3
• Recent evidence suggests rifaximin may be superior to norfloxacin for secondary prophylaxis (7% vs 39% recurrence rate) 4
• Rifaximin also reduces hepatic encephalopathy episodes compared to norfloxacin (23.1% vs 51.5%) 4

Important Considerations and Pitfalls

Antibiotic Resistance

• Long-term fluoroquinolone use increases risk of bacterial resistance 3, 2
• Weekly ciprofloxacin regimens may lead to higher rates of quinolone-resistant organisms 3, 5
• Consider local bacterial resistance patterns when selecting antibiotics 3

Adverse Effects

• Fluoroquinolones carry risks of tendon inflammation and damage, particularly in patients with renal impairment 1, 3, 2
• Monitor for signs of tendon pain or inflammation and discontinue at first sign 1
• Increased risk of Clostridium difficile infection with long-term antibiotic use 1, 2

Concomitant Medications

• Restrict proton pump inhibitor (PPI) use when possible, as PPIs may increase SBP risk 1, 3
• Carefully assess indications for long-term PPI use in cirrhotic patients 1
• Monitor non-selective beta-blockers (NSBBs) closely in end-stage liver disease with hemodynamic derangement 1

Follow-up

• All patients with a history of SBP should be considered for liver transplantation evaluation due to poor long-term survival 1, 3
• Regular monitoring of renal function is recommended in patients on prophylactic antibiotics 3, 2
• Perform diagnostic paracentesis if clinical deterioration occurs 1

Emerging Therapies

• Rifaximin shows promise for both primary and secondary prophylaxis of SBP 4, 6, 7
• In secondary prophylaxis, rifaximin may be more effective than norfloxacin (7% vs 39% recurrence) 4
• Addition of probiotics to norfloxacin does not improve efficacy in SBP prevention 8