What is the recommended treatment for a patient with suspected Spontaneous Bacterial Peritonitis (SBP)?

Treatment of Suspected Spontaneous Bacterial Peritonitis

Start empirical antibiotic therapy immediately upon diagnosis with a third-generation cephalosporin—either cefotaxime 2g IV every 8-12 hours or ceftriaxone 1-2g IV every 12-24 hours for 5-7 days—without waiting for culture results. 1, 2

Diagnostic Confirmation Before Treatment

• Perform diagnostic paracentesis in all hospitalized cirrhotic patients with ascites, even without symptoms, as 16% of SBP cases are asymptomatic 3
• Diagnose SBP when ascitic fluid polymorphonuclear (PMN) count exceeds 250/mm³, regardless of culture results 1, 3
• Inoculate at least 10 mL of ascitic fluid into blood culture bottles at bedside before starting antibiotics to increase culture sensitivity to >90% 3
• Obtain blood cultures simultaneously before antibiotic initiation 3
• Do not delay treatment waiting for culture results—the PMN count alone is sufficient to initiate therapy 1, 3

First-Line Antibiotic Regimens for Community-Acquired SBP

Cefotaxime remains the gold standard:

• Cefotaxime 2g IV every 6-8 hours achieves 77-98% resolution rates 1, 2, 4
• A dose of 4g/day (2g every 12 hours) is as effective as 8g/day (2g every 6 hours) 2, 5
• Five days of treatment is as effective as 10 days for uncomplicated cases 1, 2, 4

Ceftriaxone is equally effective:

• Ceftriaxone 1-2g IV every 12-24 hours achieves 73-100% resolution rates 1, 2, 4
• Recent 2023 multicenter RCT showed no significant difference between cefotaxime, ceftriaxone, and ciprofloxacin when using response-guided therapy 6

Alternative regimens for specific situations:

• Amoxicillin-clavulanic acid 1g/0.2g IV every 8 hours achieves 87% resolution, similar to cefotaxime 1, 2
• Oral ofloxacin 400mg every 12 hours can be used ONLY in uncomplicated SBP without renal failure, hepatic encephalopathy, GI bleeding, ileus, or shock 1, 2
• Oral ciprofloxacin 500mg every 12 hours for 5-7 days is acceptable for clinically stable patients or as step-down therapy after 2 days of IV treatment 2

Critical Caveat: When NOT to Use Quinolones

Avoid quinolones as first-line therapy in these situations: 1, 2, 4

• Patients already on quinolone prophylaxis (high resistance rates)
• Areas with high quinolone-resistant bacteria prevalence
• Nosocomial or healthcare-associated SBP
• Use cefotaxime or amoxicillin-clavulanic acid instead 1

Nosocomial SBP Requires Broader Coverage

For hospital-acquired or healthcare-associated SBP, third-generation cephalosporins have unacceptably high failure rates due to multidrug-resistant organisms (35% MDRO rate). 2, 7

• 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) 2, 7
• Consider this regimen for patients in ICU, recent hospitalization, or septic shock 2

Essential Adjunctive Therapy: IV Albumin

Administer IV albumin in addition to antibiotics—this is NOT optional: 1, 2, 4, 3

• 1.5 g/kg body weight 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% 1, 2, 3
• Albumin is particularly critical for high-risk patients with serum creatinine ≥1 mg/dL, BUN ≥30 mg/dL, or total bilirubin ≥4 mg/dL 4

Monitoring Treatment Response

• Perform repeat paracentesis at 48 hours to assess treatment efficacy 1, 2, 3
• Treatment success is defined as ascitic PMN count decreasing to <25% of pre-treatment value 1, 2, 3
• Clinical improvement should accompany laboratory response 3

Suspect treatment failure if: 1

• PMN count fails to decrease by at least 25% or increases
• Worsening clinical signs and symptoms
• No clinical improvement by 48-72 hours 4

Management of Treatment Failure

When treatment fails, consider two possibilities:

1. Resistant bacteria: 1, 3

• Modify antibiotics based on culture sensitivities
• Empirically escalate to broader-spectrum agents (e.g., meropenem plus daptomycin)

2. Secondary bacterial peritonitis (intestinal perforation or abscess): 1

• Suspect if PMN count >1,000/mm³
• Multiple organisms on Gram stain or culture
• Ascitic total protein ≥1 g/dL
• Ascitic LDH above normal serum upper limit
• Ascitic glucose ≤50 mg/dL
• Ascitic CEA >5 ng/mL or alkaline phosphatase >240 U/L
• Obtain abdominal CT imaging immediately and consider surgical consultation 1, 3

Secondary Prophylaxis After SBP Episode

All patients surviving an SBP episode require indefinite long-term antibiotic prophylaxis until liver transplantation or death: 2, 4

• Norfloxacin 400mg PO daily reduces 1-year SBP recurrence from 68% to 20% 2, 4
• Ciprofloxacin 500mg PO daily is an acceptable alternative 2, 4
• Without prophylaxis, 1-year recurrence rate is approximately 70% 4

Common Pitfalls to Avoid

• Never delay antibiotics waiting for culture results—each hour of delay increases mortality by 3.3% 3
• Never use aminoglycosides (e.g., tobramycin) due to nephrotoxicity in cirrhotic patients 2
• Never forget IV albumin—antibiotics alone are insufficient 1, 2, 3
• Never use quinolones in patients already on quinolone prophylaxis 1, 2
• Culture-negative neutrocytic ascites (PMN >250/mm³ with negative culture) should be treated identically to culture-positive SBP 3
• Recognize that nosocomial SBP has shifted toward MDROs, requiring broader initial coverage than community-acquired cases 2, 7