Treatment of Amoebiasis
Recommended Treatment Regimen
For symptomatic or invasive amoebiasis, treat with metronidazole 750 mg three times daily for 5-10 days (or tinidazole 2 grams once daily for 3-5 days as a superior alternative), followed by mandatory luminal therapy with paromomycin 30 mg/kg/day in 3 divided doses for 10 days to prevent relapse. 1, 2
Diagnostic Confirmation Before Treatment
- Do not initiate treatment unless microscopic examination of fresh feces demonstrates Entamoeba histolytica trophozoites, or two different antibiotics for shigellosis have failed after 4 days total 1
- Examine at least 3 stool samples, as organism shedding can be intermittent 3
- Fresh stool microscopy must be performed within 15-30 minutes of passage for optimal trophozoite detection 3
- For suspected amoebic liver abscess, perform indirect hemagglutination testing (>90% sensitivity) and ultrasound imaging 1
- If dysentery is present but microscopy is unavailable, treat for shigellosis first with ampicillin or TMP-SMX before considering amoebiasis 1
Critical pitfall: Distinguish large white cells (nonspecific indicator of dysentery) from actual trophozoites, as amebic dysentery tends to be misdiagnosed 1
Primary Tissue-Active Treatment
First-Line Options
Tinidazole (preferred):
- Adults: 2 grams once daily for 3-5 days 2
- Children ≥3 years: 50 mg/kg once daily (maximum 2 grams) for 3-5 days 2
- Superior efficacy and fewer side effects compared to metronidazole 2, 4
- In comparative trials, tinidazole achieved 96.5% cure rates versus 55.5% for metronidazole 4
Metronidazole (alternative):
- Adults: 750 mg three times daily for 5-10 days 1
- Children: 30 mg/kg/day divided into three doses for 5-10 days 1, 3
- Same regimen applies for both intestinal amoebiasis and amoebic liver abscess 1
Mandatory Luminal Agent (Essential Follow-Up)
After completing tissue-active therapy, all patients must receive a luminal amebicide to eliminate intestinal cysts and prevent relapse 1, 2
Luminal Agent Options
- Paromomycin: 30 mg/kg/day orally in 3 divided doses for 10 days 1, 2
- Diloxanide furoate: 500 mg orally three times daily for 10 days 1
Critical pitfall: Failure to provide luminal therapy after metronidazole/tinidazole is the most common cause of relapse 1. Studies show 72% of patients with amoebic liver abscess have asymptomatic intestinal colonization with pathogenic strains, and metronidazole alone fails to eradicate the organism from the bowel in 56% of cases 5. These carriers have propensity for recurrent invasive disease 5.
Expected Clinical Response
- Most patients with amoebic liver abscess respond within 72-96 hours of treatment initiation 1, 2
- If no improvement occurs within 2 days (intestinal disease) or 4 days (liver abscess), consider alternative diagnoses or drug resistance 1
- For persistent symptoms despite appropriate treatment, evaluate for complications or extraintestinal disease 3
Special Considerations for Amoebic Liver Abscess
- Use the same drug regimens as intestinal amoebiasis 1
- Surgical or percutaneous drainage is rarely required (only ~15% of cases) 6
- Consider drainage only for: diagnostic uncertainty, persistent symptoms after 4 days of treatment, or radiological risk of imminent rupture 1, 2
- If fever persists or systemic inflammatory response develops, perform abdominal ultrasound to evaluate for hepatic involvement 3
- Start empirical metronidazole immediately while awaiting serologic confirmation if liver abscess is suspected 3
Pediatric Dosing
- Metronidazole: 30 mg/kg/day divided into three doses for 5-10 days 1, 3
- Tinidazole: 50 mg/kg once daily (maximum 2 grams) for 3-5 days, approved for children ≥3 years 2
- Paromomycin: 30 mg/kg/day in 3 divided doses for 10 days 3
- Tinidazole tablets can be crushed for administration to children 2
- Use antimotility agents with extreme caution in young children 3
Prevention Strategies
- Emphasize hand washing after using the bathroom and before preparing or eating food 1
- Avoid consuming untreated water or uncooked food in endemic areas 1
- For patients with recent travel to endemic areas presenting with acute severe ulcerative colitis, consider adding metronidazole pending stool microscopy if amoebiasis is suspected 1