The cost of orthodox drugs and incidence of antibiotic resistance among bacteria has inspired scientists to search for natural alternatives like plants extracts as they are safer in biological system. The leaf extracts of Bryophyllum pinnatum has been used in folklore medicine in the treatment of varieties of diseases in Nigeria, India and China. Ethanol and methanol extracts of leaf of B.pinnatum were analyzed and their antibacterial activities were also tested against pathogenic bacteria isolated from cow dung. The six pathogenic bacteria isolated were identified as Salmonella entrica, Proteus mirabilis, Staphylococcus aureus, Pseudomonas aeruginosa, Vibro cholerae and E.coli. The result showed that the ethanol and methanol extracts have antibacterial properties. The pathogenicity of the isolates was studied by infecting the mice with them. There were death of two mice infected with Pseudomonas aeruginosa and Vibro cholera. Other mice in the same group with them were asymptomatic carriers. For the mice infected with Salmonella entrica, Proteus mirabilis, Pseudomonas aeruginosa, E.coli, Staphylococcus aureus and Vibro cholerae, 50×108, 20×108, 25×108, 10×108, 10×108, 2×108 cfu/ml of the infected organisms were recovered from the intestine respectively. The bacterial load in the intestine reduced drastically after the ethanol and methanol treatment.