Résumé
The ethanolic extracts of the leaves of Lemon grass and Polyalthia Longifolia were subjected to antibacterial activity study. The study indicated that the extract of the leaves of Lemon grass was very active against Klebsiella pneumonia and Staphylococcus aureus at 25mg/ml but has no activity with Bacillus subtilis and Escherichia coli at the same concentration. The extract of Polyalthia Longifolia leaves was very active against Bacillus subtilis and Staphylococcus aureus at 25mg/ml but has no activity with Klebsiella pneumonia and Escherichia coli at the same concentration. The extracts when combined together can act synergistically with one another against Staphylococcus aureus, where one extract can potentiate the activity of another extract against Staphylococcus aureus.The minimum inhibitory concentration (MIC) of the crude extracts were determined for the various organisms which ranged between 0.01 and 2.5mg/ml,while the minimum bactericidal concentration (MBC) ranged between 0.02 and 2.5mg/ml.