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Browsing by Author "Sousa, M. Isaura"

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  • Comparison between two common methods for measuring Giardia lamblia susceptibility to antiparasitic drugs in vitro
    Publication . Cruz, Agostinho; Sousa, M. Isaura; Azeredo, Zaida; Silva, M. Carolina; Sousa, J.C. Figueiredo de; Manso, Olga; Cabral, Miguel
    In this study a comparison between two different methods for measuring the susceptibility of Giardia lamblia trophozoites to metronidazole and albendazole is performed. Modifications of Meloni’s method, based on the loss of adherence of parasites to surfaces, and the Hill method, based on the loss of parasite division capacity, are compared. A logistic model was used to calculate the inhibitory concentrations IC10, IC50 and IC90 that were further compared using the respective standard errors. The results obtained, after contact of parasites with the antiparasitic drugs for 24 h, show that the adherence method is more sensitive than the multiplication method for low and moderate inhibitory concentrations of albendazole. Conversely for metronidazole the multiplication method seems to be more sensitive for high inhibitory concentrations of the drug. For screening the IC50, both methods seem to be effective, however, the inhibition of adherence method have even better performance for the benzimidazole like drugs.
    2003-10Journal article Open access Show more
  • Isolation, excystation and axenization of Giardia lamblia isolates: in vitro susceptibility to metronidazole and albendazole
    Publication . Cruz, Agostinho; Sousa, M. Isaura; Azeredo, Zaida; Leite, Emilia; Sousa, J. C. Figueiredo de; Cabral, Miguel
    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 µM for metronidazole and 0.027 and 0.192 µM 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.
    2003-04-01Journal article Open access Show more