A 48-year-old woman with decompensated cirrhosis (Child-Pugh Class C, MELD score 28) and ascites presents with fever (38.5°C), abdominal pain, and cloudy ascitic fluid. Diagnostic paracentesis shows: total protein 1.2 g/dL, polymorphonuclear (PMN) count 350/μL, and bacterial culture is pending. What is the most appropriate immediate next step in management?

Explanation

## Spontaneous Bacterial Peritonitis (SBP) in Cirrhosis ### Diagnostic Criteria and Immediate Management **Key Point:** SBP is diagnosed when ascitic PMN count ≥250/μL in the absence of a secondary cause (perforation, abscess). Empiric antibiotic therapy must be initiated immediately—do NOT wait for culture results. **High-Yield:** The ascitic PMN count (not bacterial culture positivity) is the diagnostic criterion for SBP. Cultures are positive in only ~50% of cases, but treatment should not be delayed. ### Diagnostic Criteria for SBP | Criterion | Threshold | | --- | --- | | **Ascitic PMN count** | ≥250 cells/μL (diagnostic) | | **Total protein** | <1.5 g/dL (risk factor, not diagnostic) | | **Bacterial culture** | Positive in ~50% (not required for diagnosis) | | **Secondary peritonitis** | Multiple organisms, high protein, high LDH (exclude first) | ### Immediate Management Algorithm ```mermaid flowchart TD A[Ascites + fever/peritonitis signs]:::outcome --> B[Diagnostic paracentesis]:::action B --> C{PMN ≥250/μL?}:::decision C -->|Yes| D[SBP diagnosed]:::outcome D --> E[Start empiric antibiotics immediately]:::action E --> F[Ceftriaxone 1-2g IV 8-12 hourly]:::action F --> G[Add albumin if creatinine >1.5 or bilirubin >4]:::action G --> H[Repeat paracentesis at 48h if no improvement]:::action C -->|No| I[Consider other diagnoses]:::outcome ``` ### Antibiotic Choice **Ceftriaxone** (1–2 g IV every 8–12 hours) is the empiric agent of choice because: - Excellent ascitic penetration - Covers gram-negative organisms (E. coli, Klebsiella) and gram-positive cocci - Superior to aminoglycosides (nephrotoxicity risk in cirrhosis) **Alternative:** Cefotaxime (preferred in some centres) or fluoroquinolone if allergy. ### Adjunctive Therapy **Albumin infusion** is indicated if: - Serum creatinine >1.5 mg/dL, OR - Serum bilirubin >4 mg/dL, OR - Serum sodium <130 mEq/L **Rationale:** Albumin expands effective circulating volume and reduces hepatorenal syndrome and mortality. ### Why Other Options Are Incorrect - **Await culture results:** Delaying antibiotics increases mortality; cultures are positive in only ~50% of SBP cases and should never delay empiric therapy. - **Repeat paracentesis in 48 hours:** Repeat paracentesis is performed only if clinical deterioration occurs or no improvement after 48 hours; it is not the immediate next step. - **Albumin and transplant evaluation:** While transplant evaluation is appropriate for decompensated cirrhosis, it does not address the acute life-threatening infection; antibiotics are the immediate priority. **Clinical Pearl:** SBP carries a high mortality (20–40% in-hospital) if treatment is delayed. Empiric antibiotics must be started on clinical suspicion alone, before culture results. [cite:Harrison 21e Ch 297; Robbins 10e Ch 18]