present invention the inventors have hypothesized that an ecological approach in the treatment and or prevention of giardiasis could be a colonization of the intestine with bacteria that might be able to antagonize with the parasite attachment of giardia intestinalis trophozoites to epithelial cells is deemed to be a key step for infection in humans and animals although the mechanisms for giardia adhesion are not fully understood evidence supports the ventral disk trophozoite contractile elements hydrodynamic and mechanical forces and lectin mediated binding to be involved taking into account that lactic acid is an important factor in giardia 39 s life cycle the interaction between giardia intestinalis and lactic acid bacteria has been studied using enterocyte like cells in culture to this end the following microbial parasite strains and culture media have been used bacterial strains la1 lactobacillus johnsonii i 1225 and la10 lactobacillus acidophilus i 2332 were from nestec collection lausanne switzerland and have been deposited according to the budapest treaty with the institute pasteur 28 rue du docteur roux f 75724 paris cedex 15 france on jun 30 1992 and oct 12 1999 respectively strains cidca 536 bifidobacterium bifidum and ciidca 538 bifidobacterium infantis were from the collection of centro de investigacion y desarrollo en criotecnologia de alimentos universidad nacional de la plata argentina and.