In vitro Screening of Antibacterial Activities of Selected Ethiopian Medicinal Plants

In vitro antibacterial activity of hydro-alcoholic extract of four selected medicinal plants was screened using agar well diffusion and broth dilution techniques. The four medicinal plants were leaf of Buddleja polystachya and Cordia Africana, stem bark of Albizia gummifera and areal part of Thymus schimperi. Antibacterial activity was assessed against: Pasteurella gallinarum, Salmonella gallinarum, Escherchia coli, Manhemia haemolytica, Staphylococcus aureus and Streptococcus dysagalactae. The result of agar well diffusion showed that, hydro-alcoholic extract of A. gummifera was active against all tested bacteria, B. polystachya and C. africana did not inhibit growth of all test organisms. The highest zone of inhibition was exhibited by A. gummifera against E.coli (23.5mm) and T. schimperi against S. dysagalactae (23mm). The results of broth dilution method showed that plant extracts exhibited minimum inhibitory concentration (MIC) which varied from 10-10,000 μg/ml. The plant extract B. polystachya and C. Africana did not show MIC at 10,000 μg/ml against all test organisms. The good antibacterial activity of A. gummifera and T. schimperi observed in the current study suggests that there is a potential for discovery of novel broad spectrum antimicrobial agents from indigenous medicinal plants of Ethiopia.