What medication is used for prophylaxis of Spontaneous Bacterial Peritonitis (SBP)?

Medication for Spontaneous Bacterial Peritonitis (SBP) Prophylaxis

Norfloxacin 400 mg once daily is the first-line medication for SBP prophylaxis in cirrhotic patients, recommended by both the European Association for the Study of the Liver and the American Association for the Study of Liver Diseases for both primary and secondary prophylaxis. 1, 2, 3

Secondary Prophylaxis (After Prior SBP Episode)

All patients who have recovered from an episode of SBP require continuous prophylaxis indefinitely until liver transplantation or resolution of ascites. 1, 2

First-Line Options:

• Norfloxacin 400 mg once daily orally - This is the most extensively studied agent and reduces SBP recurrence from approximately 70% to 20%, while improving 3-month survival from 62% to 94% 1, 2
• Ciprofloxacin 500 mg once daily orally - An acceptable alternative, particularly in regions where norfloxacin is unavailable 1, 2, 3

Alternative Options:

• Co-trimoxazole (800 mg sulfamethoxazole/160 mg trimethoprim) once daily - Can be used in patients who cannot tolerate fluoroquinolones, though it carries higher risk of adverse events 1, 4
• Rifaximin 550 mg twice daily - Superior to norfloxacin for secondary prophylaxis, reducing SBP recurrence from 39% to 7% and also decreasing hepatic encephalopathy episodes 5

Primary Prophylaxis (High-Risk Patients Without Prior SBP)

Primary prophylaxis is indicated when patients meet both of the following criteria 3:

1. Ascitic fluid protein <15 g/L (some guidelines use <10 g/L cutoff) 2, 3

AND at least one of:

• Child-Pugh score ≥9 with serum bilirubin ≥3 mg/dL 3
• Impaired renal function (creatinine ≥1.2 mg/dL or BUN >25 mg/dL) 3
• Hyponatremia (serum sodium ≤130 mEq/L) 3

Medication Regimen:

• Norfloxacin 400 mg once daily - Reduces 1-year probability of developing SBP from 61% to 7% and improves 3-month survival from 62% to 94% 3
• Ciprofloxacin 500 mg once daily - Acceptable alternative 3

Special Situation: Gastrointestinal Bleeding

All cirrhotic patients with acute gastrointestinal bleeding require antibiotic prophylaxis regardless of other risk factors. 2

Medication Regimen:

• Advanced liver disease: IV ceftriaxone 1g daily for 7 days 2
• Less severe disease: Norfloxacin 400 mg orally twice daily for 7 days 2

Critical Warnings and Pitfalls

Antibiotic Resistance Concerns:

• Long-term quinolone prophylaxis increases risk of gram-positive infections, including MRSA, and selects for quinolone-resistant organisms 1, 2, 3
• Avoid weekly ciprofloxacin regimens - Despite one study showing non-inferiority 6, guidelines warn that intermittent dosing may promote resistance 1
• Always consider local bacterial resistance patterns when selecting antibiotics 1, 2

Monitoring Requirements:

• Regular renal function monitoring is essential, as fluoroquinolones carry nephrotoxicity risk 1, 3
• Monitor for tendon pain or inflammation and discontinue immediately if it occurs 1, 3
• Perform diagnostic paracentesis if any clinical deterioration occurs despite prophylaxis 3

Drug Interactions:

• Restrict proton pump inhibitor (PPI) use in cirrhotic patients, as PPIs increase SBP risk 1, 2, 3

Transplant Evaluation:

• All patients requiring SBP prophylaxis should be evaluated for liver transplantation, as they have poor long-term survival (1-year mortality 50-70% after SBP without transplant) 1, 2