What are the indications for Spontaneous Bacterial Peritonitis (SBP) prophylaxis?

Indications for Spontaneous Bacterial Peritonitis (SBP) Prophylaxis

SBP prophylaxis should be administered to three specific high-risk patient populations: patients with prior SBP (secondary prophylaxis), patients with cirrhosis and gastrointestinal bleeding, and selected patients with low ascitic fluid protein and advanced liver disease (primary prophylaxis). 1, 2

Secondary Prophylaxis (Prior SBP)

• All patients who have survived an episode of SBP should receive long-term antibiotic prophylaxis due to the high recurrence rate (approximately 70% at 1 year without prophylaxis) 1, 2
• These patients should also be considered for liver transplantation evaluation due to poor long-term survival (30-50% at 1 year, 25-30% at 2 years) 2

Prophylaxis for Cirrhotic Patients with Gastrointestinal Bleeding

• All cirrhotic patients with ascites and acute gastrointestinal hemorrhage should receive short-term antibiotic prophylaxis 1, 2
• This intervention reduces infection rates, decreases rebleeding risk, and improves survival 1
• Prophylaxis should be administered until bleeding resolves and vasoactive drugs are discontinued 1

Primary Prophylaxis (No Prior SBP)

Primary prophylaxis should be offered to patients with low ascitic fluid protein (<1.5 g/dL) AND at least one of the following:

• Child-Pugh score ≥9 points with serum bilirubin >3 mg/dL 1
• Impaired renal function (serum creatinine >1.2 mg/dL, BUN >25 mg/dL) 1
• Serum sodium <130 mEq/L 1

These criteria identify patients at highest risk of developing SBP, with 1-year probability of SBP ranging from 20-60% depending on severity of liver and kidney dysfunction 1.

Recommended Prophylactic Regimens

Secondary Prophylaxis:

• First choice: Norfloxacin 400 mg once daily 1, 2
• Alternatives:
  • Ciprofloxacin 500 mg once daily 1, 2
  • Trimethoprim-sulfamethoxazole 800/160 mg daily 1, 2

For Gastrointestinal Bleeding:

• IV ceftriaxone for 7 days 1
• Alternative: Norfloxacin 400 mg twice daily for 7 days 1

Primary Prophylaxis:

• Same regimens as secondary prophylaxis 1, 2

Important Considerations and Caveats

• Prophylaxis should generally be continued indefinitely until liver transplantation or resolution of ascites 2
• Long-term antibiotic use carries risks of developing resistant organisms, especially with fluoroquinolones 1
• Fluoroquinolones may rarely cause disabling side effects affecting musculoskeletal and nervous systems 1, 2
• Regular monitoring is essential: renal function every 1-3 months and periodic cultures to detect resistant organisms 2
• Norfloxacin is no longer available in some countries (including the US since 2014), making alternatives necessary 1
• Patients receiving continuous antibiotic prophylaxis have higher risk of resistant flora when they develop infection 1

Emerging Evidence

Recent evidence suggests changing patterns of bacterial infections in cirrhosis, with increasing gram-positive and multi-drug resistant organisms 1, 3. This may affect the choice of prophylactic antibiotics in the future.

The NORFLOCIR trial showed norfloxacin did not reduce 6-month mortality in patients with advanced cirrhosis overall, but post-hoc analyses suggested benefit in patients with low ascitic fluid protein 1. This highlights the importance of careful patient selection for primary prophylaxis.

Human albumin administration (1.5 g/kg at diagnosis and 1g/kg on day 3) in addition to antibiotics for active SBP decreases the frequency of hepatorenal syndrome and improves survival 1.