Antibacterial activity of crude extract of Ocinum gratissimum (African basil) on clinical strains of Escherichia coli, Salmonella typhi and Klebsiella pneumoniae

Abstract

Ocimum gratissimum is a local plant used traditionally in Nigeria to treat ailments such as diarrheoa, pneumonia, fever etc. The antibacterial properties of ethanolic extract of Ocimum gratissimum against Escherichia coli, Salmonella typhi and Klebsiella pneumoniae were investigated using agar well/cup plate diffusion method. The percentage yield of the extract was calculated to be eighty one percent (81%) after the extraction. The result of the phytochemical screening revealed the presence of alkaloids, cardiac glycosides, saponins, tannins and steroids while flavonoids were absent. The antibacterial activity of ethanolic extract of Ocimum gratissimum revealed the greatest zone of inhibition at a concentration of 1000 μg/ml against Escherichia coli, followed by Salmonella typhi. The least zone of inhibition was observed against Klebsiella pneumoniae. At 100 μg/ml, Ocimum gratissimum exhibited the greatest zone of inhibition against Escherichia coli, followed by Salmonella typhi while Klebsiella pneumoniae had the least zone of inhibition. The MIC was determined using tube dilution technique and was found to be 100 μg/ml while the MBC was 1000 μg/ml of the extract.