摘要：It is obvious that some of resident gastrointestinal bacterial flora represented by Lactobacilli have protective role in pathogenic infections. There are many examples of probiotic effect of Lactic Acid bacteria on enteropathgens. Lactic acid bacteria are derived from the intestinal microbiota of healthy humans or dairy products. These bacteria interact with the diet and the host, contributing to protection against intestinal pathogens through colonization resistance and providing nutritional and colonic health benefits via their metabolic activities. In this study we isolated strains of Lactobacilli from Iranian traditional yogurts and identified by biochemical tests. We tested antibacterial activity of strains against Escherchia coli and salmonella typhi by spot test method. Then we assayed zone of pathogenic bacteria . Also, we determined death kinetic of pathogenic bacteria . Most of Lactobacilli strains had potential activity against the entero pathogenic bacteria of E. coli and Salmonella . This antagonistic effect against E. coli was more than Salmonella . Lactobacillus Casei showed the most preventive effect. Activity of probiotics in prevention and treatment of infections by E. coli and salmonella are effective.
