In vitro Efficacy of Metronidazole and Secnidazole combination against clinical isolates of E. histolytica

Abstract

Entamoeba histolytica is the etiological agent of amoebic dysentery and amoebic liver abscess (ALA). Worldwide, 40–50 million symptomatic cases of amoebiasis occur annually and 70,000 to 100,000 deaths are due to this infection. In amoebiasis Metronidazole, a 5-nitroimidazole drug is the drug of choice for intestinal disease caused by Entamoeba histolytica. However, the random use of Metronidazole can result in increased minimum inhibitory concentration (MIC) against Entamoeba species. As a result treatment failure may occur when treated with antiamoebic drug. Therefore, the aim of the study is to determine the efficacy of combination of Metronidazole & Secnidazole against clinical isolates of E.histolytica. The clinical isolates of E. histolytica were treated individually with Metronidazole & Secnidazole at different concentrations (2.56, 1.28, 0.64, 0.32, 0.16, 0.08 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 observed under microscope using haemocytometer. Viable counts of the E. histolytica treated with different concentration of drugs were compared with the control. The viable parasites in Control were 7.7X105 cell/ml and 5.7X105 cell/ml for testing the Metronidazole and Secnidazole respectively. Viable cell counts of E. histolytica were 3X105, 3.5X105 & 4X105 cell/ml when different concentrations of Metronidazole (2.56, 1.28 & 0.64 μg/ml) were used. Viable cell counts of E. histolytica were 2.5X105, 3.9X105 & 4.6X105 cell/ml when different concentrations of Secnidazole (2.56, 1.28 & 0.64 μg/ml) were used. Cell inhibition was maximum at the highest concentration of individual treatment (Metronidazole and Secnidazole). The parasite inhibition was occurred in a dose dependent manner. Cell inhibition of parasite was 3X105 cell/ml when treated with 2.56 μg/ml of combination drug (Metronidazole+Secnidazole). The results indicate that both Metronidazole & Secnidazole showed adequate efficacy individually against E. histolytica. However, Combination (Metronidazole+Secnidazole) of these drugs didn‟t show any synergestic effect against E. histolytica.