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

Oral Antibiotics for SBP Prophylaxis

For SBP prophylaxis, oral ciprofloxacin 500 mg daily is the recommended first-line oral antibiotic, particularly for secondary prophylaxis in patients with prior SBP episodes. 1

Patient Selection for Prophylaxis

SBP prophylaxis should be administered in the following scenarios:

Secondary Prophylaxis (Prior SBP Episode)

• All patients who have recovered from an episode of SBP should receive long-term prophylaxis until liver transplantation or resolution of ascites 1
• This group has a very high risk of recurrence (68% at 1 year without prophylaxis) 1

Primary Prophylaxis (No Prior SBP)

Primary prophylaxis should be targeted to high-risk patients:

• Patients with low ascitic fluid protein (<1.5 g/dL) AND advanced liver failure (Child-Pugh score ≥9 with serum bilirubin ≥3 mg/dL) OR impaired renal function 1
• Patients with cirrhosis and acute gastrointestinal bleeding (short-term prophylaxis) 1

Antibiotic Options and Dosing

First-line Options:

1. Ciprofloxacin 500 mg daily - Recommended alternative to norfloxacin (which was withdrawn from US market in 2014) 1
2. Trimethoprim-sulfamethoxazole - Alternative option advocated by some experts, though high-quality data are limited 1, 2
3. Rifaximin - Emerging evidence suggests it may be more effective than fluoroquinolones for secondary prophylaxis with fewer adverse events 1, 2

Alternative Dosing Regimens:

• Weekly ciprofloxacin (750 mg once weekly) has shown non-inferiority to daily norfloxacin in preventing SBP with similar survival rates 3

Duration of Prophylaxis

• Secondary prophylaxis: Continue indefinitely until liver transplantation or resolution of ascites 1
• Primary prophylaxis: Continue until resolution of risk factors or liver transplantation 1
• GI bleeding: Short-term (5-7 days) until bleeding resolves and vasoactive drugs are discontinued 1

Monitoring and Considerations

Antibiotic Resistance

• Monitor for development of resistant organisms, especially with long-term use 1
• Consider local resistance patterns when selecting antibiotics 1
• Quinolone prophylaxis is less effective in patients colonized with multidrug-resistant organisms 1

Adverse Effects

• Fluoroquinolones carry risk of tendon damage, particularly in patients with renal impairment 1
• Monitor for Clostridium difficile-associated diarrhea 1
• Discontinue at first sign of tendon pain or inflammation 1

Common Pitfalls

1. Failure to provide prophylaxis to high-risk patients - Secondary prophylaxis reduces SBP recurrence from 68% to 20% at one year 1

2. Overuse in low-risk patients - Indiscriminate use increases antibiotic resistance and adverse effects 1

3. Inadequate monitoring for resistance - Efficacy may decrease over time due to emerging resistance 1

4. Not adjusting therapy when breakthrough infections occur - Patients who develop SBP while on prophylaxis need broader coverage for treatment 1

5. Continuing prophylaxis when no longer indicated - Reassess need periodically, especially if ascites resolves 1

By following these guidelines, SBP prophylaxis can significantly reduce morbidity and mortality in cirrhotic patients with ascites who are at high risk for this serious complication.