Probiotic inhibits the cytopathic effect induced by Escherichia coli O157:H7 in Vero cell line model.

AIMS: The effectiveness of four strains of Bifidobacteria against enterohemorrhagic Escherichia coli O157:H7 infection was studied using a Vero cell model. METHODS AND RESULTS: E. coli O157 was inoculated on the Vero cell line before and after treatment with probiotic. The cytopathic effect (CPE) was evaluated during 24 h of incubation. The results indicated that Shiga toxin activity was inhibited by the probiotic. To prevent a Stx2 CPE, the probiotic needs one log more than the Stx1. CONCLUSION: The Vero cell assay, in particular, is a good model to evaluate the effect of Bifidobacteria inhibiting bacterial attachment because of soluble substances and the competitive aspect and could be used in a variety of foods like milk and yoghurt to protect pathogen bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: Probiotics could control pathogenic bacteria and Vero cell introduce as a model for evaluation of probiotics against pathogen bacteria.

Experimental infection of embryonated eggs of chicken with Besnoitia caprae.

Knowledge on parasites of the genus Besnoitia, especially Besnoitia caprae, is sparse. Besnoitia caprae, an obligate intracellular protozoan parasite belonging to the phylum Apicomplexa, is the causative agent of caprine besnoitiosis. This experiment was conducted to determine the infectivity of the bradyzoites and the resultant histopathological lesions after inoculation of B. caprae bradyzoites in the embryonated egg. Eight groups, each having six embryonated eggs, were assigned in this experiment. Seven groups were inoculated with different doses of B. caprae bradyzoite inoculums (1x10(3), 1x10(4), 1x10(5), 1x10(6), 5x10(6), 1x10(7) and 2x10(7)) via the allantoic cavity route. The 8th group was considered as control. The embryos inoculated with higher doses showed mortality between 14 and 21 days of incubation (5-12 days post-infection). Those embryos that received lower doses were hatched on day 21 of incubation; however, they presented loss of feathers and paralysis and showed hyperemia in the skin of the feet regions. Histopathological sections of the skin revealed the presence of hemorrhages, hyperemia and inflammatory responses. Some of the chickens were euthanized after 50 days postinfection (DPI) and histopathological examination of their tissues revealed haemorrhages and coagulative necrosis with the presence of mononuclear cells infiltration in the liver and heart with interstitial pneumonia. It seems that the embryonated eggs could be a useful model to study the parasite's biology.