In Vitro Efficacy Study of Ornidazole against Clinical Isolates of E. histolytica and E. Bangladeshi

Abstract

Entamoeba histolytica and Entamoeba Bangladeshi both parasites are the member of Entamoeba group. E. bangladeshi is a novel species which is identified very recently and E. histolytica is a common parasite which is the main cause of amoebiasis. The drugs of choice for invasive amoebiasis are tissue active agents, like metronidazole, Ornidazole and chloroquine or the more toxic emetine derivatives, including dehydroemetine. Ornidazole is derived from 5-nitroimdazole which kill the trophozoites by alterations in the protoplasmic organelles of the amoeba. The aim of the study is to determine the efficacy of Ornidazole against clinical isolates of E. histolytica and E. bangladeshi. The clinical isolates of E. histolytica and E. bangladeshi were treated with Ornidazole at different concentrations (0.96, 0.48, 0.24, 0.12, 0.06, 0.03 µg/ml). Drug sensitivity assay of the samples was carried out by using microtiter plates containing 100μl of parasite suspension (1×106 parasites/ml). Plates were incubated at 37ºC. After 4 hours the viable parasites were counted by haemocytometer under microscope. Viable counts of the E. histolytica and E. bangladeshi in each concentration of drugs were compared with the control. Result shows that after treatment with Ornidazole, the cell count of E. bangladeshi is higher than E. histolytica when both parasites are compared with the control (p<0.05). There is also a significant difference in percent cell inhibition between the two clinical isolates. The percent cell inhibition of E. histolytica is 30% whereas only 18% cell inhibiton is observed for E. bangladeshi. We conclude that Ornidazole is sensitive against E. bangladeshi. However, the efficacy of Ornidazole to inhibit the parasites is significant in E. histolytica than E. bangladeshi. In this study the parasite inhibition was occurred in a dose dependent manner.