What antibiotics should be ordered for an adult patient with cirrhosis and ascites diagnosed with Spontaneous Bacterial Peritonitis (SBP)?

Antibiotic Treatment for Spontaneous Bacterial Peritonitis

For adults with cirrhosis and SBP, start intravenous cefotaxime 2 grams every 8 hours immediately upon diagnosis—this is the gold standard first-line treatment with Class I, Level A evidence. 1

First-Line Empiric Therapy

Community-Acquired SBP:

• Cefotaxime 2g IV every 8 hours for 5-7 days is the preferred agent, achieving infection resolution rates of 77-98% 2, 3
• Ceftriaxone 1-2g IV every 12-24 hours is an equally effective alternative with resolution rates of 73-100% 2, 3
• Both third-generation cephalosporins provide excellent coverage against the most common pathogens (E. coli, Klebsiella, Streptococcus species) 2, 4

Dosing specifics from FDA labeling:

• Cefotaxime is approved for intra-abdominal infections including peritonitis at 1-2 grams every 6-8 hours IV for moderate to severe infections 4
• The guideline-recommended dose of 2g every 8 hours falls within this approved range and has been validated in multiple studies 1

Alternative Oral Therapy (Highly Selective Use Only)

Oral ofloxacin 400mg twice daily can substitute for IV therapy ONLY if the patient meets ALL of these criteria: 1

• No prior quinolone exposure
• No vomiting
• No shock or sepsis
• Grade I or lower hepatic encephalopathy
• Community-acquired (not nosocomial) infection
• Clinically stable presentation

This is a narrow exception—most patients require IV therapy initially. 3

Hospital-Acquired/Nosocomial SBP

For nosocomial SBP, use broader-spectrum coverage due to high rates of multidrug-resistant organisms (35% MDRO rate): 3, 5

• Meropenem 1g IV every 8 hours PLUS daptomycin 6mg/kg/day is significantly more effective than ceftazidime (86.7% vs 25% resolution rate, P<0.001) 5
• This combination should be used for patients with recent hospitalization, ICU stay, or septic shock 2
• Carbapenems may be superior to third-generation cephalosporins in critically ill patients with CLIF-SOFA scores ≥7 6

Critical Adjunctive Therapy: IV Albumin

Albumin administration is mandatory and dramatically reduces mortality: 2, 3, 7

• 1.5 g/kg IV within 6 hours of diagnosis, followed by 1.0 g/kg on day 3 2, 3
• This reduces hepatorenal syndrome from 30% to 10% and mortality from 29% to 10% 2, 3, 7
• Albumin should be given to all patients with SBP, particularly those with creatinine ≥1 mg/dL, BUN ≥30 mg/dL, or bilirubin ≥4 mg/dL 2

Treatment Duration and Monitoring

Standard treatment course: 2, 3, 8

• 5 days is sufficient for uncomplicated cases (as effective as 10 days) 2
• Extend to 7-10 days if clinical response is inadequate or resistant organisms are identified 2, 3

Repeat paracentesis at 48 hours to assess response: 2, 3

• Treatment failure is suspected if PMN count fails to decrease to <25% of baseline 2, 3
• If inadequate response, broaden coverage and investigate for secondary peritonitis or resistant organisms 2, 3

Secondary Peritonitis Considerations

If secondary peritonitis is suspected (atypical presentation, multiple organisms, or treatment failure): 1

• Add anaerobic coverage to the third-generation cephalosporin 1
• Obtain imaging (CT scan, contrast studies) to evaluate for gut perforation 1
• Surgical consultation for potential laparotomy 1

Long-Term Prophylaxis After SBP

All patients who survive SBP require indefinite prophylaxis until transplant or death: 1, 2, 3

• Norfloxacin 400mg PO daily reduces 1-year recurrence from 68% to 20% 1, 2, 3
• Alternative: Trimethoprim-sulfamethoxazole (800mg/160mg daily) or ciprofloxacin 500mg daily 1, 2
• Without prophylaxis, 70% of patients experience recurrence within one year 2, 7

Key Clinical Pitfalls

Never delay antibiotics waiting for culture results—start empiric therapy immediately upon diagnosis (PMN >250 cells/mm³). 1, 3

Avoid these common errors: 2, 3, 9

• Do not use aminoglycosides (nephrotoxic in cirrhotic patients) 3
• Do not use quinolones as first-line if patient is on quinolone prophylaxis (high resistance rates) 2
• Do not forget albumin—it is as important as antibiotics for reducing mortality 2, 3
• Do not assume community-acquired flora in hospitalized patients—nosocomial SBP requires broader coverage 5

Resistance patterns are evolving: 1, 2

• Quinolone-resistant bacteria are usually still sensitive to cefotaxime 1
• Long-term quinolone prophylaxis selects for gram-positive organisms and resistant flora 1
• Local antibiograms should guide prophylaxis choices 2, 3