A 48-year-old woman with decompensated cirrhosis develops spontaneous bacterial peritonitis (SBP) confirmed by ascitic fluid analysis (polymorphonuclear count >250 cells/μL, positive culture for E. coli). What is the drug of choice for empiric treatment?

Explanation

## Spontaneous Bacterial Peritonitis (SBP) Treatment **Key Point:** Ceftriaxone is the first-line empiric antibiotic for SBP in cirrhotic patients, covering gram-negative organisms (E. coli, Klebsiella) and gram-positive cocci. ### Rationale for Ceftriaxone **High-Yield:** Ceftriaxone achieves excellent penetration into ascitic fluid and covers >90% of SBP pathogens (predominantly gram-negative aerobic bacteria). It is the guideline-recommended first-line agent [cite:Harrison 21e Ch 308]. ### Antibiotic Comparison for SBP | Agent | Class | Coverage | Ascitic Penetration | Status | |-------|-------|----------|-------------------|--------| | **Ceftriaxone** | 3rd-gen cephalosporin | GNB, GPC | Excellent | **First-line** | | Ciprofloxacin | Fluoroquinolone | GNB | Moderate | Prophylaxis only; not empiric | | Amoxicillin-clavulanate | Beta-lactam + inhibitor | Limited GNB | Poor | Inadequate for SBP | | Piperacillin-tazobactam | Extended-spectrum | Broad | Good | Reserved for resistant/nosocomial SBP | ### Clinical Protocol 1. **Diagnostic criteria:** Ascitic PMN ≥250 cells/μL (or ≥500 if secondary peritonitis suspected) 2. **Empiric dosing:** Ceftriaxone 1–2 g IV every 8–12 hours 3. **Duration:** 7–10 days (or until clinical improvement and negative repeat culture) 4. **Adjuncts:** - Albumin (1.5 g/kg on day 1, 1 g/kg on day 3) if creatinine >1 mg/dL or bilirubin >4 mg/dL (reduces renal failure and mortality) - Repeat paracentesis at 48 hours if no improvement 5. **Secondary prophylaxis:** Norfloxacin or trimethoprim-sulfamethoxazole after SBP episode **Clinical Pearl:** Ciprofloxacin is used for *prophylaxis* in high-risk patients (ascitic protein <1.5 g/dL + impaired synthetic function), not empiric treatment of active SBP. **Mnemonic:** **CEFT-SBP** — Ceftriaxone is Empiric First-line Treatment for Spontaneous Bacterial Peritonitis. **Warning:** Do not use oral fluoroquinolones (ciprofloxacin) as empiric therapy for SBP; they are suboptimal for acute infection and reserved for prophylaxis only.