Antibacterial effects of extracts of Ocimum gratissimum and piper guineense on Escherichia coli and Staphylococcus aureus

The upsurge in the prevalence of side effects of many synthetic antimicrobial agents and incidence of multidrug resistant bacteria has spurred scientists on the research for plant based antimicrobial of therapeutic potentials. Ocimum gratissimum and Piper guineense present such potential of high medicinal value. These plants are used in Nigeria traditionally as condiments and for treatment of various ailments such as pyorrhea, dysentery and bronchitis. Aqueous and ethanol extracts of O. gratissimum and P. guineense leaves were screened for antibacterial activity against Escherichia coli and Staphylococcus aureus. Both extracts were found to exhibit selective inhibition against the isolates. The diameter zones of inhibition exhibited by the extracts were between 2 + 0.01 – 10 + 0.10 mm. The minimum inhibitory concentration (MIC) determined by the agar diffusion method was between 10.00 and 2.50 mg/ml-1. Ethanol extracts showed more inhibitory effect compared to the aqueous extracts. Results obtained show that the extracts of O. gratissimum and P. guineense possess some level of antibacterial activities against E. coli and S. aureus. Key words: Ocimum gratissimum, Piper guineense, antibacteria