## Empiric Antibiotic Coverage in Acute Cholangitis **Key Point:** Acute cholangitis requires broad-spectrum coverage of gram-negative aerobes, gram-positive cocci, and anaerobes pending culture results. ### Rationale for Ceftriaxone + Metronidazole - **Ceftriaxone:** Third-generation cephalosporin with excellent biliary penetration and broad gram-negative coverage (E. coli, Klebsiella, Enterobacter) - **Metronidazole:** Covers anaerobes (Bacteroides, Clostridium) that are frequently cultured from infected bile - **Combined regimen:** Covers the polymicrobial flora typical of ascending cholangitis ### Alternative Regimens (Context-Dependent) | Regimen | Indication | Notes | |---------|-----------|-------| | Piperacillin-tazobactam | Monotherapy option | Single agent covering gram-negative, gram-positive, and anaerobes | | Carbapenems (meropenem) | Severe sepsis or β-lactamase producers | Reserve for critically ill or resistant organisms | | Fluoroquinolone + metronidazole | Penicillin allergy | Less preferred due to lower anaerobic coverage | **Clinical Pearl:** Antibiotics should be started immediately after blood cultures (do not delay for culture results). Definitive treatment (ERCP ± sphincterotomy or percutaneous transhepatic cholangiography) follows once sepsis is controlled. **High-Yield:** The classic triad of Charcot's triad (fever, jaundice, RUQ pain) indicates acute cholangitis and mandates emergency decompression after antibiotic initiation.
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