Intrinsic susceptibility of Giardia duodenalis assemblage subtypes A(I), A(II), B and E(III) for nitric oxide under axenic culture conditions.

The antigiardial effects of nitric oxide (NO·) have been reported in vitro, but only for assemblage A(I) lab strains. This study investigated the intrinsic NO· susceptibility of different assemblage subtypes. The susceptibility (IC₅₀) for NO· released by MAHMA NONOate was studied for three lab (WB, G1 and GS/M-83-H7) and six field isolates of assemblage subtypes A(I), A(II), B and E(III).

Infectivity of Giardia duodenalis Assemblages A and E for the gerbil and axenisation of duodenal trophozoites.

Establishing in vitro cultures of Giardia duodenalis trophozoites from faecal cysts remains very difficult due to poor excystation and bacterial contamination. This study investigated an alternative approach starting from duodenal trophozoites of gerbils that were artificially infected with field isolates from humans (Assemblages A and B) and cattle (Assemblage E and mixed E/A). Gerbil infection was successful for Assemblages A (1/1) and B (1/3) from humans, and for E (1/2) and mixed E/A (6/6) from cattle.

A new quantitative in vitro microculture method for Giardia duodenalis trophozoites.

A reliable, rapid and low-cost method for drug sensitivity determination of Giardia duodenalis trophozoites (WB-strain) was developed in a 96-well plate. Using a standard inoculum of 5 x 10(4) trophozoites per well (300 microl), good growth was obtained after sealing the plate with an air-tight adhesive tape and incubation at 37 degrees C for 72 h in modified TYI-S-33 medium. Viable burdens were quantified using the formazan dyes MTT (100 microg/well) and XTT (20 microg/well) and the fluorescent substrate resazurin (2.