Background: Entamoeba histolytica infection is common in developing countries, and up to 100,000 individuals with severe disease die every year. Adequate therapy for amoebic colitis is necessary to reduce the severity of illness, prevent development of complicated disease and extraintestinal spread, and decrease transmission.
Objectives: To evaluate antiamoebic drugs for treating amoebic colitis.
Search strategy: In September 2008, we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (2008, Issue 3), MEDLINE, EMBASE, LILACS, mRCT, and conference proceedings. We contacted individual researchers, organizations, and pharmaceutical companies, and checked reference lists.
Selection criteria: Randomized controlled trials of antiamoebic drugs given alone or in combination, compared with placebo or another antiamoebic drug for treating adults and children diagnosed with amoebic colitis.
Data collection and analysis: Two authors independently assessed the eligibility and methodological quality of trials, and extracted and analysed the data. We calculated clinical and parasitological failure rates, relapse, and adverse events as risk ratios (RR) with 95% confidence intervals (CIs), using a random-effects model. We determined statistical heterogeneity and explored possible sources of heterogeneity using subgroup analyses. We carried out sensitivity analysis using trial quality to assess the robustness of the results.
Main results: Thirty-seven trials, enrolling 4487 participants, met the inclusion criteria. Only one trial used adequate methods for randomization and allocation concealment, was blinded, and analysed all randomized participants. Only one trial used a E. histolytica stool antigen test. Tinidazole reduced clinical failure compared with metronidazole (RR 0.28, 95% CI 0.15 to 0.51; 477 participants, eight trials) and was associated with fewer adverse events. Compared with metronidazole, combination therapy resulted in fewer parasitological failures (RR 0.36, 95% CI 0.15 to 0.86; 720 participants, 3 trials).
Authors' conclusions: Tinidazole is more effective in reducing clinical failure compared with metronidazole and has fewer associated adverse events. Combination drug therapy is more effective in reducing parasitological failure compared with metronidazole alone. However, these results are based on trials with poor methodological quality so there is uncertainty in these conclusions. Further trials of the efficacy of antiamoebic drugs, with better methodological quality, are recommended. More accurate tests to detect E. histolytica are needed, particularly in countries where concomitant infection with other bacteria and parasites is common.