What is the initial management for a patient with spontaneous bacterial peritonitis (SBP)?

Management of Spontaneous Bacterial Peritonitis

Immediately initiate empirical antibiotic therapy with a third-generation cephalosporin (cefotaxime 2g IV every 8 hours or ceftriaxone 1-2g IV every 12-24 hours) plus intravenous albumin (1.5 g/kg at diagnosis, then 1.0 g/kg on day 3) as soon as the diagnosis is confirmed by ascitic fluid neutrophil count >250/mm³. 1

Immediate Diagnostic Steps

Before initiating treatment, perform these essential diagnostic procedures:

• Obtain diagnostic paracentesis in all patients with cirrhosis and ascites presenting with fever, abdominal pain, altered mental status, worsening ascites, GI bleeding, shock, or any signs of systemic inflammation 1
• Send ascitic fluid for cell count with differential (diagnosis requires neutrophil count >250/mm³) 1
• Inoculate ascitic fluid into blood culture bottles at bedside to maximize culture yield 1
• Obtain blood cultures before starting antibiotics 1

First-Line Antibiotic Therapy

Community-Acquired SBP

Use third-generation cephalosporins as first-line therapy, which achieve infection resolution rates of 77-98%:

• Cefotaxime 2g IV every 8 hours (or 4g/day total, as effective as 8g/day) for 5 days 1, 2
• Ceftriaxone 1-2g IV every 12-24 hours for 5-7 days (resolution rates 73-100%) 3, 4, 5

These agents provide optimal coverage for the most common causative organisms (E. coli, Klebsiella, Streptococcus species) and achieve high ascitic fluid concentrations 1, 6

Hospital-Acquired or Healthcare-Associated SBP

Broaden coverage immediately due to high rates of multidrug-resistant organisms (35% MDRO rate):

• Meropenem 1g IV every 8 hours plus daptomycin 6mg/kg/day in settings with high MDRO prevalence, particularly for ICU patients, recent hospitalizations, or septic shock 7, 4
• Piperacillin-tazobactam is an alternative broad-spectrum option 7, 8

Alternative Regimens (Community-Acquired Only)

• Amoxicillin/clavulanic acid (1g/0.2g IV every 8 hours, then switch to 0.5g/0.125g PO every 8 hours) achieves 87% resolution rate, though concerns exist regarding drug-induced liver injury 1, 4
• Oral ofloxacin 400mg every 12 hours for uncomplicated SBP only (without renal failure, hepatic encephalopathy, GI bleeding, ileus, or shock) 1
• Ciprofloxacin (200mg IV every 12 hours for 7 days, or switch therapy with 200mg IV every 12 hours for 2 days then 500mg PO every 12 hours for 5 days) 1, 3

Critical caveat: Never use quinolones in patients already on quinolone prophylaxis, in areas with high quinolone resistance, or in nosocomial SBP 1, 3

Mandatory Adjunctive Therapy: Intravenous Albumin

Administer IV albumin to all patients with SBP, which reduces hepatorenal syndrome from 30% to 10% and mortality from 29% to 10%:

• 1.5 g/kg body weight at diagnosis (within 6 hours) 1, 7, 4
• 1.0 g/kg on day 3 1, 7, 4

Albumin is particularly critical in patients with baseline serum bilirubin ≥4 mg/dL or serum creatinine ≥1 mg/dL 1, 3

The benefit of albumin is independent of antibiotic therapy and cannot be replaced by crystalloids or other colloids 1

Monitoring Treatment Response

• Perform repeat paracentesis at 48 hours to assess treatment efficacy 1, 7, 4
• Treatment failure is defined as ascitic neutrophil count failing to decrease to <25% of pre-treatment value 1, 3
• If inadequate response, suspect resistant bacteria or secondary bacterial peritonitis and broaden antibiotic coverage 1, 7

Duration of Therapy

• 5 days of treatment is as effective as 10 days for uncomplicated SBP with appropriate clinical response 1, 3
• Extend therapy beyond 5 days if clinical response is inadequate or cultures reveal resistant organisms 3
• Adjust antibiotics based on culture results once available, narrowing spectrum when possible for antibiotic stewardship 7, 4

Critical Pitfalls to Avoid

• Never delay antibiotics waiting for culture results—empirical therapy must start immediately upon diagnosis 1, 7, 4
• Never use aminoglycosides (e.g., tobramycin) due to nephrotoxicity in cirrhotic patients 1, 7, 4
• Never omit albumin administration—it provides mortality benefit independent of antibiotics and is not optional 1, 7, 4
• Never assume SBP in patients with surgical drains or recent abdominal procedures—always rule out secondary bacterial peritonitis first with CT imaging 7

Distinguishing Secondary Bacterial Peritonitis

Suspect secondary peritonitis (requiring surgical intervention) if:

• Multiple organisms on ascitic culture 1
• Very high ascitic neutrophil count 1
• High ascitic protein concentration (>1 g/dL) 7
• Inadequate response to appropriate antibiotic therapy 1
• Ascitic fluid glucose <50 mg/dL or LDH greater than serum LDH 7

Obtain prompt CT scanning and early surgical consultation in these cases 1, 7

Secondary Prophylaxis After SBP

All patients surviving an episode of SBP require indefinite secondary prophylaxis until ascites resolves or liver transplantation occurs:

• Norfloxacin 400mg PO daily (reduces 1-year recurrence from 68% to 20%) 7, 3, 4
• Ciprofloxacin 500mg PO daily as alternative 7, 3, 4

The 1-year recurrence rate without prophylaxis is approximately 70%, making long-term prophylaxis essential 3