Content area
Full Text
Amoebiasis caused by Entamoeba histolytica, is a major public health problem in developing countries. Morphologically similar E. dispar is non pathogenic. Because of the redefinition of E. histolytica and E. dispar, and the limited number of antiamoebic drugs available, a new approach to treat such individuals is necessary. The cost of treating asymptomatic individuals is highly exorbitant and not justifiable. The indiscriminate use of antiamoebic drugs can result in increased minimum inhibitory concentration (MIC) values against Entamoeba species, and treatment failure may emerge as an important public health problem. Development of new antiamoebic drugs is still in infancy and vaccine development appears to be distant dream. In future, the development of drug resistance may seriously affect the control of disease. This review discusses the factors involved in drug resistance mechanisms developed by the parasite.
Key words Amoebiasis * emetine * in vitro sensitivity * metronidazole * multidrug resistance mechanism
Entamoeba histolytica, associated with high morbidity and mortality continues to be a major public health problem throughout the world. Asymptomatic individuals account tor almost 90 per cent of the infections1. Poverty, ignorance, overcrowding, poor sanitation and malnutrition favour transmission and increased disease burden2. Prevalence varies from country to country and within a country3-6. In India, it was estimated to be 2-55 per cent in early nineties7. Identification of two morphologically similar Entamoeba sp., pathogenic E. histolytica and non pathogenic E. dispar responsible for asymptomatic infection, have raised the question of treating all such cases8. The recommendation is that E. histolytica should be specifically identified, treated with antiamoebic drugs. In individuals with only E. dispar, the treatment is unnecessary. Treating asymptomatic individuals indiscriminately may lead to drug resistance. Though it does not appear to be a serious problem now, reports of failed treatment with metronidazole19 and differences in drug susceptibilities10-13 do suggest that this could probably herald the development of drug resistance clinically. Therefore, understanding the mechanisms involved in multi drug resistance of different antiamoebic drugs is essential.
Antiamoebic drugs
Antiamoebic drugs are classified into three groups: luminal, tissue, and mixed amoebicides. Metronidazole is the major drug of choice and other nitroimidazole derived compounds like tinidazole. secnidazole and ornidazole are equally effective. Diloxanide furcate, diiodohydroxyquin, paromomycin, emetine and chloroquine have also been used as alternate...