The antimicrobial activities of flower and leaf extract of Ocimum gratissimum obtained from the garden of the Faculty of Pharmacy and Pharmaceutical Sciences, Kwame Nkrumah University of Science and Technology Ghana, was tested against Staphylococcus aureus, Bacillus subtilis (Gram positive bacteria), Klebsiella pneumonia, Pseudomonas aeruginosa, Escherichia coli (Gram negative bacteria) and Candida albicans (fungi). These extracts were produced from cold extraction of petroleum ether and ethanol solutions at room temperature. Zones of inhibition were obtained using the disc diffusion method. The extracts showed varied level of antimicrobial activities against the tested microorganism. The activity spectrum indicates wide coherence towards Gram positive and negative bacteria and the fungi tested. Petroleum ether flower extract exhibited great activity against C. albicans, while petroleum flower extract exhibited the least activity against B. subtilis.

Keywords: Antimicrobial activity, Ocimum gratissimum, disc diffusion method, plant extract, Knust, Ghana.