Abstract:To observe the antibacterial effect of essential oils on multidrug-resistant Acinetobacter baumannii (MDRAB) in vitro, the inhibitory zone diameter and the minimum inhibitory concentration (MIC) of seven essential oils on MDRAB were measured by disk diffusion method and micro-broth dilution method, the strongest antibacterial essential oil was found and then its dynamic germicidal curve against MDRAB was drawn. The combinatory effect of the two lowest MIC essential oils on MDRAB was studied by the checkerboard dilution method. The results showed that cinnamon essential oil has the strongest antibacterial effect on MDRAB. The inhibition zone diameter is 29.30±1.16 mm, the MIC value is 0.62 μL/mL, and the antibacterial activity against MDRAB is dependent on the drug concentration. A synergistic effect was observed with the combination of cinnamon oil with peppermint oil. Additive effect was observed with the combination of cinnamon oil and lavender oil. Furthermore, peppermint oil and lavender oil had stronger antibacterial effect, MIC value were 1.25 μL/mL and 2.50 μL/mL, respectively. Clove oil had moderate antibacterial activity on MDRAB, the MIC value was 10 μL/mL. The antibacterial effect of wintergreen oil and green tea oil on MDRAB were relatively weak, the MIC value was 20 μL/mL. The inhibitory effect of benzoin essential oil on MDRAB was weak or not detected. It was concluded that cinnamon oil had the strongest antibacterial effect on MDRAB and was concentration-dependent. In addition, cinnamon essential oil and lavender essential oil as well as cinnamon essential oil and peppermint essential oil had synergistic anti-MDRAB effect, providing effective guidance for clinical use.
