Amoebic colitis is caused by the parasite Entamoeba histolytica. This protozoan is distributed throughout the world and is commonly acquired by ingestion of contaminated food or water. It is estimated that about 40 to 50 million people infected with E. histolytica develop amoebic colitis or extraintestinal abscesses, which result in up to 100,000 deaths per year.
Metronidazole is currently the drug of choice for treating invasive amoebiasis in adults and children, but it may not be sufficient to eliminate parasite cysts in the intestine. Combinations with other drugs are therefore also used. However, the evidence to support combination therapy has not been reviewed. Also, some unpleasant adverse effects associated with metronidazole in some patients, and the possibility of parasite resistance to metronidazole has to be considered.
This review compares different drugs used against amoebic colitis, alone or in combination, and also assesses single-dose regimens versus longer regimens.
Thirty-seven trials with 4487 participants were included, and only one was of high methodological quality. Tinidazole reduced clinical failure compared with metronidazole and was associated with fewer adverse events. Combination therapy resulted in fewer parasitological failures than metronidazole alone.
The authors conclude that tinidazole appears more effective at reducing clinical failures than metronidazole, and has fewer associated adverse events. There is insufficient evidence to draw conclusions regarding the efficacy of the other antiamoebic drugs. However, the trials' methodological quality was generally inadequate. Also, the choice of antiamoebic drugs would depend largely on the availability and accessibility of drugs.
Better quality randomized trials with standardized outcomes are needed to evaluate the efficacy of drugs for treating amoebic colitis. There is also a need for improved, reliable diagnostic tests that can be used in developing countries.
Dans, L.F.; Martinez, E.G.; Gonzales, M.L.M. Antiamoebic drugs for treating amoebic colitis. Cochrane Database of Systematic Reviews (2009) (Issue 2) Art. No.: CD006085. [DOI: 10.1002/14651858.CD006085.pub2]