Antiamoebic drugs for treating amoebic colitis

09 Jan 2019

What is the aim of this review?

This Cochrane Review aims to determine the effectiveness and safety of drugs used to treat people with amoebic colitis, which is an infection of the large intestines caused by the parasite, Entamoeba histolytica. Cochrane researchers searched for all relevant studies to answer this question and included 41 relevant studies in this review.

Key messages

Tinidazole may be more effective than metronidazole for reducing clinical symptoms and may be associated with fewer adverse events. Combination therapy resulted in fewer parasitological failures than occurred with metronidazole alone. Evidence is insufficient to allow conclusions regarding the efficacy of other antiamoebic drugs. Better quality randomized trials using accurate diagnostic methods and standardized outcomes are needed to evaluate the efficacy of drugs for treating individuals with amoebic colitis.

What was studied in the review?

Entamoeba histolytica is distributed throughout the world and is commonly acquired by ingestion of contaminated food or water. An estimated 40 to 50 million people infected with E histolytica develop amoebic colitis or extraintestinal abscesses, resulting in up to 100,000 deaths per year.

Metronidazole is currently the standard therapy for treating adults and children with invasive amoebiasis, but it may not be sufficient to eliminate amoebic cysts from the intestine. Some unpleasant adverse effects have been associated with metronidazole, and the possibility of parasite resistance to metronidazole has led to the development of alternative drugs. Combinations of metronidazole with other drugs that eradicate surviving cysts in the intestines have been recommended, so evidence to support this approach needs to be assessed.

This review compares different drugs used against amoebic colitis, alone or in combination, and also assesses single‐dose regimens versus longer regimens.

What are the main results of the review?

This review included 41 studies, most of which were conducted in countries considered to be highly endemic for amoebiasis. Most trials were old: 30 were conducted before 1998. Trials varied in the inclusion criteria used to enrol participants and in the definition and timing of measured outcomes. Stool microscopy with direct wet saline smear was the method used most often to detect the presence of E histolytica in stools. Study participants ranged in age from seven months to 80 years. Included trials reported a variety of comparisons and involved 25 individual drugs, two herbal products, and 15 different combinations.

The review shows that in individuals with amoebic colitis, tinidazole may be better for reducing clinical symptoms (low‐certainty evidence) and probably results in fewer adverse events when compared with metronidazole (moderate‐certainty evidence). However, we do not know whether it is more effective for eradicating amoebae from the stools. Combination drug therapy may be more effective than metronidazole alone for eradicating amoebae (low‐certainty evidence), but we are uncertain which drug combination is most effective, and if combination treatment will lead to more rapid resolution of clinical symptoms or in more adverse events (very low‐certainty evidence). Evidence is insufficient to allow conclusions regarding efficacy of the other antiamoebic drugs.

How up‐to‐date is this review?
The review authors searched for studies that had been published up to 22 March 2018.