in vitro culture and isoenzyme analysis of giardia lamblia

difficult to produce viable cultures.
Use of surrogate animals as excystation hosts proved to be superior to in vitro
excystment. Viable cultures of Giardia have been established using this model.
Subsequently six local strains have been axenised for the first time in South
Africa. The greater numbers of trophozoites available for culture initiation as well
as the reduction of contaminating faecal organisms are considered to be key
factors in the efficacy of this method.
In the present study only a limited number of in vivo excysted trophozoites
resulted in the establishment of a successful culture. Therefore the establishment
of viable cultures of Giardia through mice inoculations can be considered to be
dependant on many complex factors such as: Giardia isolate variations, mouse
strain variations, selection pressures placed by both in vivo and in vitro conditions
and the fact that Giardia is fastidious with no defined medium being available for
these organisms. Little is known about the growth dynamics of populations of
Giardia. Furthermore, previous studies reflect that multiple attempts are required
to successfully initiate viable cultures of a single isolate. For example, Kasprzak &
Majewska (1985) reported that up to 107 consecutive attempts were required to
isolate strains (from faecal cysts or duodenal aspirates) in vitro. Owing to the
limited numbers of cysts available for simultaneous in vitro and in vivo
experiments, few faecal samples allowed for repeated attempts in the current
work.
While working with Giardia it became clear that establishment of these organisms
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