A 42-year-old woman from West Bengal presents with fever, right upper quadrant pain, and hepatomegaly. Ultrasound abdomen shows a 6 cm hypoechoic lesion in the right lobe of liver with a 'granular' appearance. Serology is positive for E. histolytica. Stool examination is negative for cysts. What is the drug of choice for amoebic liver abscess?

Explanation

## Treatment of Amoebic Liver Abscess **Key Point:** Amoebic liver abscess (ALA) is a **tissue-invasive form** of E. histolytica infection. The primary pathology is in the liver parenchyma, not the intestinal lumen. Treatment requires a **tissue-acting amoebicide**, not a luminal agent. ### Site-Specific Drug Selection in Amoebiasis | Clinical Form | Primary Site | Drug of Choice | Rationale | |---|---|---|---| | **Asymptomatic cyst passer** | Luminal | Diloxanide furoate | Eliminate cysts before invasion | | **Acute dysentery** | Intestinal mucosa | Metronidazole + diloxanide | Tissue invasion + luminal clearance | | **Amoebic liver abscess** | **Hepatic parenchyma** | **Metronidazole** | **High liver penetration, kills trophozoites in abscess cavity** | | Chronic colitis | Intestinal | Metronidazole + diloxanide | Tissue + luminal | ### Why Metronidazole for Liver Abscess 1. **Excellent hepatic penetration**: Achieves high concentrations in liver tissue and abscess fluid 2. **Kills trophozoites** in the abscess cavity (anaerobic environment) 3. **Rapid clinical response**: Fever and pain resolve within 3–5 days 4. **Standard regimen**: Metronidazole 750 mg TDS × 7–10 days (or 2.4 g daily × 5–10 days) 5. **Followed by luminal agent**: After abscess resolution, give diloxanide furoate to eliminate intestinal cysts and prevent relapse **High-Yield:** Chloroquine was historically used but is now **second-line** because metronidazole has superior efficacy and faster response. Chloroquine is reserved for patients who cannot tolerate metronidazole or have contraindications. **Clinical Pearl:** Amoebic liver abscess often occurs **without active dysentery** (stool may be negative for cysts). The abscess is a consequence of prior intestinal invasion, not ongoing luminal colonization. **Warning:** Do NOT confuse the drug for intestinal amoebiasis (diloxanide) with the drug for hepatic amoebiasis (metronidazole). The site of disease determines the drug choice.