What is the recommended treatment for a patient suspected of having amoebiasis?

Treatment of Amoebiasis

For suspected amoebiasis, treat with metronidazole 750 mg three times daily for 5-10 days (adults) or 30 mg/kg/day for 5-10 days (children), followed by a luminal agent such as paromomycin 30 mg/kg/day in 3 divided doses for 10 days to prevent relapse. 1

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
• If dysentery is present but microscopy is unavailable or trophozoites are not definitively identified, treat for shigellosis first with ampicillin or TMP-SMX before considering amoebiasis. 1
• Take care to distinguish large white cells (nonspecific indicator of dysentery) from actual trophozoites, as amebic dysentery tends to be misdiagnosed. 1
• For amoebic liver abscess, indirect hemagglutination testing has over 90% sensitivity and should be performed in suspected cases. 1
• Ultrasound should be performed in all patients with suspected amoebic liver abscess; consider CT scan if ultrasound is negative but clinical suspicion remains high. 1

Treatment Regimens

Intestinal Amoebiasis and Amoebic Liver Abscess

Tissue-active agent (first phase):

• Adults: Metronidazole 750 mg orally three times daily for 5-10 days 1
• Children: Metronidazole 30 mg/kg/day for 5-10 days 1
• Same drug regimens are used for both intestinal amoebiasis and amoebic liver abscess. 1
• Most patients with amoebic liver abscess will respond within 72-96 hours of treatment initiation. 1

Luminal agent (second phase - critical to prevent relapse):

• After completion of metronidazole treatment, all patients must receive a luminal amebicide to eliminate intestinal cysts and prevent relapse. 1
• Paromomycin: 30 mg/kg/day orally in 3 divided doses for 10 days 1, 2
• Alternative: Diloxanide furoate 500 mg orally three times daily for 10 days 1

Alternative Tissue-Active Agent

• Tinidazole 2 g once daily for 3 days is FDA-approved for intestinal amebiasis and amebic liver abscess in adults and children >3 years. 3
• Research shows tinidazole achieves 90-96.5% cure rates compared to 53-58% for metronidazole in short-course regimens, though these studies used 3-day courses rather than the standard 5-10 days. 4, 5, 6
• Tinidazole is better tolerated with fewer side effects than metronidazole. 4, 5, 6

Treatment Monitoring and Failure

• If no improvement occurs within 2 days of treatment initiation, consider alternative diagnoses or drug resistance. 1
• For amoebic liver abscess, surgical or percutaneous drainage is rarely required and should only be considered in cases of diagnostic uncertainty, persistent symptoms after 4 days of treatment, or risk of imminent rupture. 1

Critical Pitfalls to Avoid

• Failure to provide a luminal agent after metronidazole/tinidazole therapy is the most common cause of relapse. 1
• Misdiagnosis between amebic and bacterial dysentery leads to inappropriate treatment. 1
• Metronidazole and tinidazole alone are ineffective for asymptomatic cyst passage due to rapid absorption and short duration of treatment. 7
• Tinidazole is not indicated for asymptomatic cyst passage. 3
• For acute severe ulcerative colitis with recent travel to endemic areas, consider adding metronidazole pending stool microscopy if amoebiasis is suspected. 1

Prevention

• 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