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

Indications for Spontaneous Bacterial Peritonitis (SBP) Prophylaxis

Three distinct clinical scenarios mandate SBP prophylaxis in cirrhotic patients: (1) prior history of SBP (secondary prophylaxis), (2) acute gastrointestinal hemorrhage, and (3) high-risk ascites with low protein content combined with markers of advanced disease (primary prophylaxis). 1, 2

Secondary Prophylaxis (Prior SBP)

All patients who have recovered from an episode of SBP require indefinite antibiotic prophylaxis due to the exceptionally high recurrence risk of 68% at one year without treatment. 2, 3

• Norfloxacin 400 mg orally once daily is the first-line agent, reducing recurrence from 68% to 20% at one year. 2, 3
• Ciprofloxacin 500 mg orally once daily serves as an acceptable alternative, particularly where norfloxacin is unavailable. 1, 2
• Prophylaxis should continue until liver transplantation or complete resolution of ascites. 3
• All patients with prior SBP warrant liver transplantation evaluation given poor long-term survival. 2

Prophylaxis During Acute Gastrointestinal Hemorrhage

Every cirrhotic patient with acute gastrointestinal bleeding requires antibiotic prophylaxis regardless of whether ascites is present, as bacterial infections (including SBP) occur in 25-65% of these patients and significantly increase rebleeding rates and mortality. 4, 2

• IV ceftriaxone 1g daily for 7 days is recommended for patients with advanced liver disease. 2
• Norfloxacin 400 mg orally twice daily for 7 days is an alternative for less severe disease. 4
• This represents the most frequently overlooked indication for prophylaxis in clinical practice. 5

Primary Prophylaxis (High-Risk Patients Without Prior SBP)

Primary prophylaxis is indicated for patients with ascitic fluid protein <15 g/L (or <1.5 g/dL) PLUS at least one of the following high-risk features: 1, 2

• Child-Pugh score ≥9 with serum bilirubin ≥3 mg/dL 1
• Impaired renal function (creatinine ≥1.2 mg/dL or BUN ≥25 mg/dL) 1
• Hyponatremia (serum sodium ≤130 mEq/L) 1

Recommended Regimen for Primary Prophylaxis

• Norfloxacin 400 mg orally once daily reduces one-year SBP probability from 61% to 7% and improves three-month survival from 62% to 94%. 1
• Ciprofloxacin 500 mg orally once daily is an alternative in regions with limited norfloxacin availability. 1
• Norfloxacin also reduces hepatorenal syndrome risk from 41% to 28%. 1

Critical Pitfalls and Considerations

The most common error is failing to initiate prophylaxis during gastrointestinal hemorrhage, which accounted for 44% of preventable SBP cases in one analysis. 5 A retrospective study found that 62% of SBP cases were preventable through adherence to guidelines, with GI hemorrhage being the most frequently overlooked indication. 5

Emerging Resistance Concerns

• Long-term fluoroquinolone use increases risk of gram-positive infections (including MRSA) and multidrug-resistant organisms. 2, 6
• The epidemiology has shifted toward more gram-positive cocci and quinolone-resistant bacteria. 4, 6
• Consider local resistance patterns when selecting antibiotics. 2

Monitoring Requirements

• Regular clinical assessment for fever, abdominal pain, or encephalopathy. 1
• Periodic renal function monitoring given fluoroquinolone nephrotoxicity risk, particularly in patients with baseline renal impairment. 1
• Vigilance for Clostridium difficile infection with long-term antibiotic use. 1

Additional Risk Modification

• Strongly consider discontinuing or avoiding proton pump inhibitors in patients on SBP prophylaxis, as acid suppression increases SBP risk. 3, 6
• Discontinue beta-blockers in patients with refractory ascites or end-stage disease, as they are associated with increased SBP risk. 6

Alternative Agents (Not Currently Guideline-Recommended)

While rifaximin showed promise in a network meta-analysis ranking it highest for SBP prevention 7, current EASL, AASLD, and BSG guidelines do not endorse rifaximin for SBP prophylaxis due to insufficient evidence from high-quality trials. 3 Trimethoprim-sulfamethoxazole has been studied but is not a first-line recommendation. 8