Isolation, excystation and axenization of Giardia lamblia isolates:: in vitro susceptibility to metronidazole and albendazole

From 53 samples of human faeces containing Giardia lamblia cysts, 18 isolates were successfully excysted in vitro, and cultivated axenically in TYI-S-33 modified medium. The in vitro effects of metronidazole and albendazole on these isolates were evaluated by the trophozoite adherence inhibition method. The IC50 was between 2.4 and 11.5 muM for metronidazole and 0.027 and 0.192 muM for albendazole. These IC50 values were similar to those found for the ATCC 30888 and 30957 reference isolates. All isolates were susceptible to the antiparasitic drugs tested. These results suggest that resistance of G. lamblia to metronidazole and albendazole does not seem to be a significant problem in our population.