Synergistic antibacterial effects of Moroccan Artemisia herba alba, Lavandula angustifolia and Rosmarinus officinalis essential oils

Purpose The antibacterial effects of three essential oils were tested against three bacterial strains (ATCC: Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa) commonly known for their implication on wound healing infections. Methods The disc diffusion method and the determination of the Minimal Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) were carried out to evaluate their antibacterial activity. The combined effect of essential oils against the tested bacteria was assessed by the checkerboard method and the Fractional Inhibitory Concentration Index (FICI) calculation. Results The results of the dissemination method demonstrated that the three EOs have antibacterial activity against the three tested bacteria at 20 μl. Concerning the MIC, Lavender, Rosemary and Wormwood essential oils inhibited the bacterial growth at 1.33, 3.33 and 42.67 μl/ml; 1.33 1.67 and 42.67 μl/ml ; and 4.00, 6.67 and 42.67 μl/ml for S. aureus, E. coli and P. aeruginosa, respectively. The evaluation of the essential oils in combination revealed that the maximum of required concentration were 0.5 μl/ml for Artemisia herba alba and 1 μl/ml for Lavandula angustifolia and Rosmarinus officinalis. Conclusions These results indicate a synergism for the combination of lavender, wormwood and rosemary essential oils at very low concentrations compared to MICs.