ASSESSMENT OF THE ANTIMICROBIAL ACTIVITY OF OLIVE OIL AGAINST SOME BACTERIAL FOOD PATHOGENS

Abstract

Extra virgin olive oil sample was screened against isolates of Staphylococcus aureus, Escherichia coli, Enterobacter aerogenes, and Yersinia enterocolitica using the agar well diffusion method. Most of the microorganisms screened were sensitive to the olive oil and this was dose dependent. The most sensitive organism at 100% dilution was S. aureus with a zone of inhibiton of 36 mm, followed by E. coli and E. aerogenes both having 26 mm inhibiton. The least sensitive was Y. enterocolitica with a zone of 18 mm while absolute resistance was observed in A. niger (0 mm) even at the highest concentration of the olive oil. Varying multiple resistance to conventional antibiotics was observed from test isolates with maximum zones of inhibition of 20 mm, 19 mm, and 16 mm for S. aureus, E. coli, both E. aerogenes and Y. enterocolitica respectively. With a minimum inhibitory concentration of 0.013mg/ml against S. aureus, E. coli and Y. enterocolitica, it can be concluded that olive oil has good antibacterial effect at low concentrations. This suggests that olive oil may represent a better therapeutic agent to control infections of the Gastro-intestinal Tract (GIT)