Inhibitory effect and disinfectant activity of Syzygium aromaticum L. and Ocimum gratissimum L. essential oils against Escherichia coli and Staphylococcus aureus isolated from sheep carcasses

Abstract

Syzygium aromaticum L. and Ocimum gratissimum L. essential oils were tested for their effectiveness in reduction the counts of inoculated Staphylococcus aureus and Escherichia coli in sheepmeat. The inhibitory effect was analysed by disk diffusion and broth macrodilution method with four strains and seven concentrations. Disinfectant activity of the oils was assessed using the suspension test with two strains and two concentrations. The inhibition was observed at concentrations 400, 200 and 100 μL/mL. Syzygium aromaticum L. oil was better than Ocimum gratissimum L. against bacteria isolated from sheep carcasses. The minimum bactericidal concentration of the essential oils aginst inocula ranged from 50 to 200 μL/mL. The suspension test showed that after 5 minutes of contact, Syzygium aromaticum L. disinfectant at 400 μL/mL deactivated the inoculants completely. The results demonstrated that essential oils exerted a significant bactericidal and bacteriostatic action against pathogens.