What is the treatment for amebic dysentery?

Treatment of Amebic Dysentery

Treat confirmed amebic dysentery with metronidazole 750 mg orally three times daily for 5-10 days (adults) or 30 mg/kg/day for 5-10 days (children), followed by a luminal amebicide such as paromomycin or diloxanide furoate to prevent relapse. 1, 2, 3

Critical Diagnostic Considerations Before Treatment

Do not treat for amebiasis without microscopic confirmation or documented failure of two different antibiotics for shigellosis. 2 This is essential because:

• Amebic dysentery is frequently misdiagnosed, leading to inappropriate treatment and delays in proper management of bacterial dysentery 2
• Stool specimens must be examined microscopically for Entamoeba histolytica trophozoites, ideally within 15-30 minutes of passage 4, 2
• Large white blood cells (nonspecific indicators of dysentery) are commonly mistaken for amebic trophozoites 2
• If microscopy is unavailable or trophozoites are not definitively seen, treat initially for shigellosis with cephalosporins or fluoroquinolones 4

First-Line Treatment Algorithm

Step 1: Tissue Amebicide (Metronidazole or Tinidazole)

Adults: 1, 2, 3

• Metronidazole 750 mg orally three times daily for 5-10 days
• Alternative: Tinidazole (same regimen as metronidazole) 4, 5

Children: 1

• Metronidazole 30 mg/kg/day for 5-10 days

Expected response: Most patients respond within 72-96 hours of treatment initiation 1

Step 2: Luminal Amebicide (Mandatory Follow-up)

After completing metronidazole or tinidazole, all patients must receive a luminal amebicide to eliminate intestinal cysts and prevent relapse, even if follow-up stool microscopy is negative. 1, 2 Options include:

• Paromomycin: 30 mg/kg/day orally in 3 divided doses for 10 days 1, 6
• Diloxanide furoate: 500 mg orally three times daily for 10 days 1

Critical Pitfall to Avoid

Failure to follow tissue amebicide with luminal amebicide results in treatment failure and relapse. 2 This is the most common error in amebic dysentery management, as metronidazole alone has poor efficacy against intestinal cysts despite excellent cure rates (>90%) for invasive disease 1, 7.

Treatment Failure Management

If no improvement occurs within 2 days of treatment initiation: 1

• Reconsider the diagnosis (bacterial dysentery is more common)
• Consider drug resistance (rare)
• Ensure proper medication adherence

Special Considerations for Amoebic Liver Abscess

• Use the same drug regimens as intestinal amebiasis 1
• Most patients respond within 72-96 hours 1
• Surgical or percutaneous drainage is rarely required and should only be considered for diagnostic uncertainty, persistent symptoms after 4 days of treatment, or risk of imminent rupture 1
• Indirect hemagglutination testing has >90% sensitivity and should be performed in suspected cases 1

Quinolone Resistance Consideration

When treating empirically for bacterial dysentery (before confirming amebiasis), note that quinolone resistance is increasingly reported in campylobacter isolates from Asia; in these cases, consider a macrolide instead 4.