Antagonism of Lactobacillus johnsonii La1 against Giardia intestinalis: an in vivo study.

4 HUMEN, M. A.; DE ANTONI, G. L.; BENYACOUB, J.; COSTAS, M. E.; CARDOZO, M. I.; KOZUBSKY, L.; SAUDAN, K-Y.; BOENZLI-BRUAND, A.; BLUM, S.; SCHIFFRIN, E. J. AND PÉREZ, P. F.

Buenos Aires

Congreso; XVII Congreso Latinoamericano de Microbiología. X Congreso Argentino de Microbiología.; 2004

Giardia intestinalis is the etiological agent of giardiasis, an intestinal infection leading to diarrhea and malabsorption in humans and animals. Treatment of giardiasis is generally conducted through antibiotics (e. g. nitroimidazoles and nitrofurans) but the occurrence of resistant strains leads to clinical failures worldwide. In addition, several side effects of anti-Giardia drugs have been reported. Colonization by Giardia strongly depends on the intestinal microflora and in vitro studies shows that some probiotic lactobacilli (e. g. Lactobacillus johnsonii La1) interfere with the cell cycle of Giardia intestinalis. This anti-giardial effect does not seems to be a general property of lactobacilli and encourages further research on an ecological approach for the prevention and treatment of giardiasis by means of selected probiotic strains. In the present study, we sought to gain further insight on the inhibitory properties of Lactobacillus johnsonii La1 (NCC533) against Giardia intestinalis by means of an in vivo model of giardiasis (Meriones unguiculatus). Animals were allowed to drink bacterial suspensions (around 108 CFU per animal per day) ad libitum starting at day –7 prior infection with 5 x 105 trophozoites of Giardia intestinalis strain WB clone C6 grown in TYI-S-33 medium. At days 7, 14 and 21 post-infection, samples were taken in order to determine trophozoite load in duodenum, intestinal sucrase activity, fecal antigens (GSA65 protein), proliferation of spleen cells and cysts in feces. Also, histological analysis of mesenteric lymph nodes, Peyer patches and small intestine were performed. Administration of lactobacilli efficiently prevents Giardia intestinalis strain WB clone C6 from infecting gerbils. A diminution of the ratio of animals showing active trophozoites in their small intestine was observed. Also, shedding of fecal giardia antigens (GSA65 protein) was diminished in the La1-treated group and no signs of infection were evident in treated gerbils at 21 days post-infection. Probiotic administration was associated with protection of the mucosal damage induced by the parasite as assessed by histological analysis and enzymatic markers of microvillus membrane integrity. In addition, a stimulation of the response against giardia antigens was found in spleen cells of the La1-treated gerbils. Results show for the first time, the anti-giardial effect of a probiotic lactobacilli in vivo and add further insight on the antagonistic properties of lactic acid bacteria against protozoa involved in intestinal infections. is the etiological agent of giardiasis, an intestinal infection leading to diarrhea and malabsorption in humans and animals. Treatment of giardiasis is generally conducted through antibiotics (e. g. nitroimidazoles and nitrofurans) but the occurrence of resistant strains leads to clinical failures worldwide. In addition, several side effects of anti-Giardia drugs have been reported. Colonization by Giardia strongly depends on the intestinal microflora and in vitro studies shows that some probiotic lactobacilli (e. g. Lactobacillus johnsonii La1) interfere with the cell cycle of Giardia intestinalis. This anti-giardial effect does not seems to be a general property of lactobacilli and encourages further research on an ecological approach for the prevention and treatment of giardiasis by means of selected probiotic strains. In the present study, we sought to gain further insight on the inhibitory properties of Lactobacillus johnsonii La1 (NCC533) against Giardia intestinalis by means of an in vivo model of giardiasis (Meriones unguiculatus). Animals were allowed to drink bacterial suspensions (around 108 CFU per animal per day) ad libitum starting at day –7 prior infection with 5 x 105 trophozoites of Giardia intestinalis strain WB clone C6 grown in TYI-S-33 medium. At days 7, 14 and 21 post-infection, samples were taken in order to determine trophozoite load in duodenum, intestinal sucrase activity, fecal antigens (GSA65 protein), proliferation of spleen cells and cysts in feces. Also, histological analysis of mesenteric lymph nodes, Peyer patches and small intestine were performed. Administration of lactobacilli efficiently prevents Giardia intestinalis strain WB clone C6 from infecting gerbils. A diminution of the ratio of animals showing active trophozoites in their small intestine was observed. Also, shedding of fecal giardia antigens (GSA65 protein) was diminished in the La1-treated group and no signs of infection were evident in treated gerbils at 21 days post-infection. Probiotic administration was associated with protection of the mucosal damage induced by the parasite as assessed by histological analysis and enzymatic markers of microvillus membrane integrity. In addition, a stimulation of the response against giardia antigens was found in spleen cells of the La1-treated gerbils. Results show for the first time, the anti-giardial effect of a probiotic lactobacilli in vivo and add further insight on the antagonistic properties of lactic acid bacteria against protozoa involved in intestinal infections.