Combined antibacterial effect of Origanum essential oils and antibiotics against multiresistant foodborne Salmonella isolated from poultry and shellfish in Morocco

Abstract The present study aims to assess the antibacterial activity of endemic Moroccan Origanum essential oils (Origanum elongatum and Origanum compactum) alone and in association with antibiotics against multidrug resistant foodborne Salmonella. The well diffusion and microdilution procedures were used to evaluate the antibacterial activity. The synergistic interactions between antibiotics and EOs were determined using the checkerboard assay. The results of the antibacterial activity indicated that all of Salmonella serovars isolates that were examined were highly inhibited by EOs. This effect was confirmed by the microdilution technique, where 0.125% was noted as the smallest MIC value. Based on the obtained MBC values, O. elongatum shown a bactericidal action against the tested strains as indicated by the acquired MBC values. While O. compactum showed this effect against different serovars of Salmonella isolates. Origanum EOs could be employed as an alternative to the former protocols against resistant infectious diseases.