What is the recommended prophylaxis for Spontaneous Bacterial Peritonitis (SBP)?

Spontaneous Bacterial Peritonitis (SBP) Prophylaxis

Norfloxacin 400 mg once daily is the first-line antibiotic for SBP prophylaxis in high-risk cirrhotic patients with ascites, with ciprofloxacin 500 mg once daily or trimethoprim-sulfamethoxazole 800/160 mg daily as alternatives. 1

Indications for SBP Prophylaxis

SBP prophylaxis should be administered in three specific high-risk populations:

1. Primary Prophylaxis (patients with no prior SBP):

   • Patients with low ascitic fluid protein (<1.5 g/dL) AND advanced liver disease (Child-Pugh score ≥9 with serum bilirubin >3 mg/dL, impaired renal function, or serum sodium <130 mEq/L) 2, 1

2. Secondary Prophylaxis (patients with previous SBP):

   • All patients who have recovered from an episode of SBP should receive indefinite antibiotic prophylaxis until liver transplantation or resolution of ascites 2, 1

3. Patients with Acute Gastrointestinal Bleeding:

   • All cirrhotic patients with ascites and gastrointestinal bleeding should receive short-term prophylaxis (5-7 days) 2, 1

Antibiotic Options for SBP Prophylaxis

Antibiotic	Dosage	Indication	Recommendation Level
Norfloxacin	400 mg once daily	Primary & secondary prophylaxis	First choice [2,1]
Ciprofloxacin	500 mg once daily	Alternative to norfloxacin	Strong alternative [2,1]
Trimethoprim-Sulfamethoxazole	800/160 mg daily	Alternative option	Alternative option [2,1]
Rifaximin	Various dosing	Emerging alternative	Emerging evidence suggests superior efficacy [1,3,4]

Special Considerations

1. For Gastrointestinal Bleeding:

   • Short-term prophylaxis (5-7 days) is recommended
   • Cefotaxime has been widely studied but choice should be guided by local resistance patterns 2
   • Norfloxacin 400 mg twice daily for 7 days is an established regimen 1, 5

2. For Secondary Prophylaxis:

   • Recent evidence suggests rifaximin may be more effective than norfloxacin with fewer adverse events and lower mortality 3, 4
   • Long-term prophylaxis should continue until liver transplantation or resolution of ascites 1

3. Monitoring During Prophylaxis:

   • Regular assessment of renal function (every 1-3 months)
   • Periodic cultures to detect resistant organisms
   • Monitor for antibiotic side effects, particularly with long-term use 1

Clinical Pitfalls and Caveats

• Underutilization of Prophylaxis: Studies show that SBP prophylaxis is frequently underused, with gastrointestinal hemorrhage being the most commonly overlooked indication 6
• Antibiotic Resistance: Long-term quinolone prophylaxis may lead to resistant infections, requiring careful monitoring 1, 4
• PPI Avoidance: Acid suppressants (PPIs, H2-blockers) should be avoided in patients with SBP risk as they may increase infection risk 1
• Transplant Evaluation: Patients who develop SBP have poor long-term prognosis and should be evaluated for liver transplantation 1

Treatment of Active SBP

While not the focus of the question, it's worth noting that when active SBP occurs:

• Immediate empirical antibiotic therapy should be initiated
• Cefotaxime 2g IV every 8 hours for 5 days is the standard treatment 2, 5
• Albumin infusion (1.5 g/kg on day 1 g/kg on day 3) should be added for patients with renal dysfunction or hyperbilirubinemia to reduce mortality and prevent hepatorenal syndrome 2, 1

The most recent guidelines emphasize the importance of appropriate prophylaxis in high-risk patients, with norfloxacin remaining the first-line agent while acknowledging emerging evidence for rifaximin's potential superiority in certain scenarios.