Effectiveness of Beilschmiedia ugandensis against Staphylococcus aureus and Escherichia coli

Abstract

The study was carried out to assess the effectiveness of Beilschmiedia ugandensis extract, a traditional tree on two pathogens, Escherichia coli (gram negative) and Staphylococcus aureus (gram positive) commonly known to be etiological agents of diarrheal diseases. Crude extracts were obtained using solvent extraction technique with ethanol used as extracting solvent. Antibacterial activity of the extract was tested using agar-well diffusion technique on Mueller Hinton (MH) media and broth dilution in nutrient broth. Of the two bacteria tested, Staphylococcus aureus turned out to be relatively more susceptible than Escherichia coli with mean diameter zone of inhibition of 21.78mm for Escherichia coli and 29.89mm for Staphylococcus aureus using methanolic extracts, while Escherichia coli was more susceptible than Staphylococcus aureus with the aqueous extracts with mean diameter zone of inhibition of 26.00mm and 23.78mm respectively. From analysis of variance, methanolic leaf extracts had lower antibacterial activity compared to aqueous leaf extracts of Beilschmiedia ugandensis on Escherichia coli with a P-value 0.000355 at 95% level of confidence. For Staphylococcus aureus, aqueous leaf extracts exhibited more activity compared to methanolic extract with a P-value 0.000444 at 95% level of confidence. In conclusion, Beilschmiedia ugandensis methanolic and aqueous extracts possessed antibacterial activity against Escherichia coli and Staphylococcus aureus whose values of zone of inhibition are close to those of the positive control having a zone of inhibition of 32.89mm for E.coli and 36.67mm for S.aureus.