In-vitro Screening of Antimicrobial Activities of Ocimum gratissimum on Clinical Isolates

This study was undertaken to evaluate the antimicrobial activities of crude ethanol and methanol extracts of the leaves of Ocimum gratissimum L. (scent leaf) on Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus auerus and Candida albicans.The antimicrobial activities were carried out using agar well diffusion method. The Minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) of the plant extracts on the test isolates were determined by the agar dilution method. Ciprofloxacin and fluconazole (positive controls) were used in comparison with crude extract of O. gratissimum leaves and also, Dimethyl sulfoxide (DMSO) was used as the negative control. The ethanolic extract of O. gratissimum showed antibacterial activity with the mean inhibitory zone diameter of 3 -7mm against S. auerus, 2 mm against E. coli, 2 – 12 mm against K. pneumoniae, 2 mm against P.aeruginosa. Ethanol and methanol crude extracts of O. gratissimum leaves showed no effect on C.albicans. O. gratissimum extracts showed the lower antimicrobial activity than the commercially available antibiotics (ciprofloxacin and fluconazole). The minimum Inhibitory Concentration and Minimum Bactericidal Concentration of the extracts on the test organisms also increased in the following order; methanol < ethanol. Hence, this extract could only serve as antibacterial agent in the management of bacterial infection because it has no antifungal activities on Candida isolates used in this study.