What is the recommended treatment for spontaneous bacterial peritonitis in an adult with cirrhosis and ascites?

Treatment of Spontaneous Bacterial Peritonitis in Adults with Cirrhosis and Ascites

Immediate Empirical Antibiotic Therapy

Start intravenous cefotaxime 2 g every 8 hours immediately upon diagnosis (ascitic fluid PMN count >250/mm³) without waiting for culture results. 1, 2, 3

First-Line Antibiotic Regimens

• Cefotaxime 2 g IV every 8 hours is the gold-standard empirical therapy for community-acquired SBP, achieving infection resolution rates of 77–98%. 1, 2, 3
• Ceftriaxone 1–2 g IV every 12–24 hours is equally effective, with resolution rates of 73–100%. 1, 3
• A total daily cefotaxime dose of 4 g (2 g every 12 hours) is clinically equivalent to 8 g/day, though every-8-hour dosing provides more consistent coverage in severe presentations. 1, 4, 5
• Treatment duration: 5 days is sufficient for uncomplicated SBP; extending to 10 days provides no additional benefit. 1, 2, 3

Alternative Oral Therapy (Highly Selected Patients Only)

• Oral ofloxacin 400 mg twice daily may replace IV cefotaxime only in patients meeting all of these criteria: 1
  • Community-acquired SBP (not nosocomial)
  • No prior quinolone exposure or prophylaxis
  • No vomiting, shock, or septic shock
  • No grade II or higher hepatic encephalopathy
  • Serum creatinine <3 mg/dL
• This oral strategy applies to approximately 60% of SBP cases. 1
• Ciprofloxacin 500 mg PO every 12 hours is an alternative for uncomplicated cases meeting the same strict criteria. 1, 2

Nosocomial or Healthcare-Associated SBP

• Meropenem 1 g IV every 8 hours plus daptomycin 6 mg/kg/day is required for nosocomial SBP due to high rates of multidrug-resistant organisms (35% MDRO rate). 2, 6
• This combination is significantly more effective than ceftazidime (86.7% vs. 25% resolution rate; P <0.001). 6
• Consider broader coverage for patients with recent hospitalization, ICU stay, or septic shock. 1, 2

Essential Adjunctive Albumin Therapy

Administer IV albumin 1.5 g/kg body weight within 6 hours of diagnosis, followed by 1.0 g/kg on day 3, for all patients with high-risk features. 1, 2, 3

• High-risk criteria include any of the following: 1, 3
  • Serum creatinine ≥1 mg/dL
  • Blood urea nitrogen ≥30 mg/dL
  • Total bilirubin ≥4 mg/dL
• This regimen reduces mortality from 29% to 10% and prevents hepatorenal syndrome (reduces incidence from 30% to 10%). 1, 2, 3
• Albumin is superior to hydroxyethyl starch for this indication. 1

Monitoring Treatment Response

• Perform repeat diagnostic paracentesis at 48 hours to assess treatment efficacy. 1, 2, 3
• Treatment failure is defined as ascitic PMN count failing to decrease to <25% of baseline value. 1, 2, 3
• If treatment failure occurs, broaden antibiotic coverage and investigate for secondary bacterial peritonitis or resistant organisms. 1, 2
• Antibiotics can be discontinued once ascitic fluid PMN count falls below 250 cells/µL, typically by day 4–5 of appropriate therapy. 1

Distinguishing Secondary Bacterial Peritonitis

Suspect secondary peritonitis (gastrointestinal perforation) when ascitic fluid shows ≥2 of the following: 1

• Total protein >1 g/dL
• Lactate dehydrogenase > upper limit of normal for serum
• Glucose <50 mg/dL
• Polymicrobial culture growth

When secondary peritonitis is suspected, add anaerobic coverage and obtain urgent surgical consultation. 1

Long-Term Secondary Prophylaxis

All patients surviving an SBP episode require indefinite antibiotic prophylaxis until liver transplantation or death. 1, 3

• Norfloxacin 400 mg PO once daily is the most extensively studied regimen, reducing 1-year SBP recurrence from 68% to 20%. 1, 3
• Ciprofloxacin 500 mg PO once daily is an acceptable alternative when norfloxacin is unavailable. 1, 3
• Co-trimoxazole (800 mg sulfamethoxazole/160 mg trimethoprim) once daily is another alternative. 1
• The 1-year recurrence rate without prophylaxis exceeds 70%, making recurrence almost inevitable. 1

Critical Contraindications and Pitfalls

• Never delay antibiotics waiting for culture results—empirical therapy must start immediately upon diagnosis. 2, 3
• Avoid aminoglycosides (tobramycin, gentamicin) due to nephrotoxicity and inferior efficacy compared to cefotaxime. 2, 4
• Do not use quinolones as first-line therapy in patients with: 1, 2
  • Current quinolone prophylaxis (high resistance rates)
  • Septic shock, renal failure, or hepatic encephalopathy
  • Gastrointestinal bleeding or ileus
  • Nosocomial acquisition
• If SBP recurs while on quinolone prophylaxis, switch treatment to a third-generation cephalosporin due to quinolone-resistant organisms. 1
• Increasing bacterial resistance is a major concern; nosocomial SBP now has a 35% MDRO rate requiring broader initial coverage. 2, 7, 8
• Discontinue proton-pump inhibitors when feasible, as they increase SBP risk. 1, 8