How to prevent and treat spontaneous bacterial peritonitis (SBP) in a patient with liver disease and gross ascites?

Prevention and Treatment of Spontaneous Bacterial Peritonitis (SBP)

Immediate Treatment of Suspected or Confirmed SBP

Start empirical IV antibiotics immediately when ascitic fluid polymorphonuclear (PMN) count exceeds 250 cells/mm³, before culture results are available. 1

First-Line Antibiotic Selection

Community-Acquired SBP:

• IV cefotaxime 2g every 8-12 hours is the gold standard first-line treatment with resolution rates of 77-98% 1, 2
• Alternative: IV ceftriaxone 1-2g once daily (resolution rates 73-100%) 2
• Treatment duration: 5-7 days for uncomplicated cases, with 5 days sufficient for most patients showing appropriate clinical response 2

Hospital-Acquired or Critically Ill Patients:

• Use broader coverage with carbapenems (meropenem 1g IV every 8 hours) immediately in septic shock or ICU patients, as inappropriate initial therapy increases mortality risk 10-fold 1, 3
• This is critical because multidrug-resistant organisms (MDROs) represent 35% of infections in cirrhotic patients, and cephalosporins have become less effective in these settings 1, 3

Critical Adjunctive Therapy: IV Albumin

Administer IV albumin 1.5 g/kg within 6 hours of SBP diagnosis, followed by 1.0 g/kg on day 3 in patients with high-risk features (creatinine ≥1 mg/dL, BUN ≥30 mg/dL, or bilirubin ≥4 mg/dL) 2, 3

• This reduces mortality from 29% to 10% and prevents hepatorenal syndrome (reduces from 30% to 10%) 2, 3
• Never give antibiotics alone without albumin in high-risk patients—the combination is essential 3

Monitoring Treatment Response

• Perform repeat diagnostic paracentesis at 48 hours to assess treatment efficacy, especially if clinical response is inadequate 1, 2
• Treatment failure is defined as PMN count decrease <25% from baseline, which should prompt investigation for secondary peritonitis or resistant organisms 2, 3

---

Diagnostic Approach

Every cirrhotic patient with ascites admitted to the hospital requires immediate diagnostic paracentesis to rule out SBP, even without symptoms of infection. 1

When to Perform Paracentesis:

• All hospital admissions with ascites 1
• Fever, abdominal pain/tenderness, or signs of systemic inflammation 1
• Hepatic encephalopathy, renal failure, acidosis, or peripheral leukocytosis 1
• GI bleeding or shock 1
• Worsening liver or renal function 1

Culture Technique:

• Inoculate at least 10 mL of ascitic fluid into blood culture bottles at bedside before starting antibiotics, which increases culture sensitivity to >90% 1
• Obtain simultaneous blood cultures to increase organism isolation rates 1, 3

---

Prevention Strategies

Secondary Prophylaxis (After SBP Episode)

All patients who survive an episode of SBP require indefinite long-term prophylaxis until liver transplantation or death, as the 1-year recurrence rate without prophylaxis is approximately 70% 1, 4

Recommended regimens:

• Norfloxacin 400 mg once daily (most extensively studied, reduces recurrence from 68% to 20%) 1, 4
• Ciprofloxacin 500 mg once daily (acceptable alternative, commonly used in UK where norfloxacin availability is limited) 1, 4
• Co-trimoxazole 800 mg sulfamethoxazole/160 mg trimethoprim once daily 1

Primary Prophylaxis (High-Risk Patients Without Prior SBP)

Offer prophylaxis to patients with ascitic fluid protein <1.5 g/dL and advanced liver disease, as this significantly improves 3-month survival and reduces SBP development 1, 4

• Use same antibiotic regimens as secondary prophylaxis 1, 4
• Continue indefinitely until liver transplantation or death 4

Prophylaxis During GI Bleeding

All cirrhotic patients with GI bleeding require antibiotic prophylaxis, as bacterial infections occur in 25-65% of these patients and significantly increase rebleeding rates and mortality 1, 4

Regimen selection based on disease severity:

• Advanced/severe liver disease: IV ceftriaxone 1g daily for 7 days (preferred due to better coverage against quinolone-resistant organisms) 2, 4
• Less severe disease: Norfloxacin 400 mg twice daily for 7 days 4
• Continue until hemorrhage resolves and vasoactive drugs are discontinued 2

---

Important Caveats and Pitfalls

Antibiotic Resistance Concerns:

• Never use quinolones (ciprofloxacin/norfloxacin) as first-line treatment in patients already on quinolone prophylaxis due to high resistance rates 2
• There has been a shift toward gram-positive and multidrug-resistant organisms, particularly in nosocomial and healthcare-associated SBP (35% of infections) 1
• Long-term quinolone prophylaxis increases risk of gram-positive infections including MRSA 4

Treatment Failures:

• If no clinical improvement by 48-72 hours, suspect resistant organisms or secondary bacterial peritonitis 2
• Secondary peritonitis (from gut perforation) requires anaerobic coverage plus surgical consultation 1
• Suspect secondary peritonitis if ascitic fluid shows: protein >1 g/dL, LDH greater than upper limit of normal for serum, glucose <50 mg/dL, or polymicrobial culture 1

Critical Don'ts:

• Never delay antibiotics waiting for culture results—start empirically once PMN >250/mm³ 3
• Avoid aminoglycosides due to nephrotoxicity in patients already at high hepatorenal syndrome risk 3
• Do not place chest tube for spontaneous bacterial empyema (pleural fluid PMN >250/mm³), despite the term "empyema"—treat with antibiotics only 1
• Temporarily hold non-selective beta-blockers if mean arterial pressure <65 mmHg or acute kidney injury develops 3

Prophylaxis Stewardship:

• Reserve prophylaxis only for truly high-risk patients to minimize development of resistance 2, 4
• Consider local bacterial resistance patterns when selecting prophylactic antibiotics 4
• All patients with prior SBP should be evaluated for liver transplantation due to poor long-term survival 4