Anti-Giardia lamblia activity of ginger (Zingiber officinale) extract in an improved modified axenic culture

Abstract

Background Giardiasis is an important common intestinal infection that occurs as a result of ingestion of cysts of the protozoan parasite Giardia lamblia. Several medications are available to treat giardiasis. Metronidazole and other chemical drugs currently used for treatment cause side effects, whereas ginger has been used for centuries as a herbal medicine, without harmful side effects. Objective With regard to the above-mentioned properties of ginger we were prompted to evaluate its anti-Giardia activity, as compared with nitazoxanide (NTZ) and phosphate buffer saline (PBS) as controls, and to establish a G. lamblia axenic culture that yields a large number of trophozoites. Materials and methods Fresh clinical isolates of G. lamblia were obtained from different patients with acute giardiasis. Trophozoites were cultured using Stone’s modification of Locke’s solution as an axenic culture medium modified by supplementing with bovine bile and heat-inactivated bovine serum. Ginger extract was prepared to give a final concentration of 20 mg/ml. In vitro assessment of effect of ginger was carried out after 24 and 48 h. For post-treatment evaluation, the viability of G. lamblia trophozoites was tested by their morphological criteria and dye staining (eosin stain 0.01%). Results The culture yielded a rich growth of G. lamblia trophozoites. Dead trophozoites stained pink with eosin and showed loss of morphological criteria. NTZ treatment significantly lowered the number of the parasites after 48 h (mean: 42.5±3.53/ml; P≤0.002), with a reduction rate of 92.93%, compared with PBS. Ginger treatment significantly lowered the number of the parasites after 48 h (mean: 55±7.07/ml, P≤0.004), with a reduction rate of 94.4%, compared with PBS. Conclusion The present study confirmed that ginger extract is equally active against G. lamblia as NTZ. More research studies are needed to highlight the physiological and molecular mechanisms of action of ginger and provide more scientific evidence of its effectiveness. Moreover, this simple G. lamblia axenic culture medium proved beneficial for evaluation of the susceptibility of isolates to antiparasitic drugs.