In vitro antimicrobial activity of selected Ethiopian medicinal plants against some bacteria of veterinary importance

Due to rapid development of resistance and high cost of the new generation antibiotics, lots of efforts are being made to discover new antimicrobial agents from different sources. In the current study aqueous and hydro-alcoholic extracts of leaves of Jasminium abyssinicum, Myrsine africana, Foenicum vulgare and aerial part of Leonotis ocymifolia were screened for antibacterial activity using agar well diffusion and broth dilution methods. Species of bacteria that cause various diseases in domestic animals namely, Escherichia coli, Pasteurella gallinarum, Manhaemia haemolytica, Salmonella gallinarum, Salmonella typhimurium, Staphylococcus aureus and Streptococcus agalactae were used for investigation of antibacterial activity. Except for aqueous extract of L. ocymifolia, all of the plant extracts demonstrated remarkable antibacterial activity on most of the bacterial species tested. The three highest zones of inhibition was exhibited by aqueous extracts of M. africana against S. aureus (19.5 mm), J. abyssinicum against M. haemolytica (19 mm) and F. vulgare against P. gallinarium (19 mm). The minimum inhibitory concentration (MIC) exhibited by the plants against test organisms varied from 10 - 1000 mu g /ml. However, no plant extract has shown antibacterial effect against E. coli using both agar well diffusion and broth dilution methods at concentrations tested. Further detailed in vitro and in vivo evaluation of these medicinal plants should be carried out.