EVALUATION OF THE EFFECTS OF ALBENDAZOLE AND METRONIDAZOLE ON THE ULTRASTRUCTURE OF GIARDIA-DUODENALIS, TRICHOMONAS-VAGINALIS AND SPIRONUCLEUS-MURIS USING TRANSMISSION ELECTRON-MICROSCOPY

The three closely related parasitic protozoa, Giardia duodenalis, Tric homonas vaginalis and Spironucleus muris, all have very different sens itivities to albendazole and metronidazole. Ultrastructural studies re veal that the cytoskeletal elements of the ventral disk in G. duodenal is are affected by albendazole, whereas the other two parasites, neith er of which possess this structure, are not affected by albendazole to the same extent. This suggests that albendazole may be having its pri mary affect on G. duodenalis by binding to cytoskeletal proteins and u ltimately causing death of the parasite. Death may be occurring as the parasite loses its ability to adhere to the intestinal villi and obta in nutrients. Metronidazole showed a different pattern of activity aga inst the three parasites. The evidence obtained from these ultrastruct ural studies supports the current theory that metronidazole adversely affects protozoa by disrupting inner cell membranes.