Anti-bacterial effect and its mechanism of lavender essential oil against multi-drug resistant Acinetobacter baumannii

To investigate the antibacterial effect and its preliminary mechanism of lavender essential oil on multi-drug resistant Acinetobacter baumannii.

Micro-dilution method was used to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of lavender essential oil against multi-drug resistant Acinetobacter baumannii, and bactericidal kinetic study was employed to determine the onset and maintenance time of lavender essential oil. Meanwhile, the promoting and therapeutic effects of lavender essential oil on wound healing were observed in a mouse model of infection. Subsequently, crystal violet staining was used to determine the inhibition and clearance of multi-drug resistant Acinetobacter baumannii biofilm by lavender essential oil, and laser confocal microscopy was utilized to observe the survival of bacteria in biofilms. NanoDrop instrument was utilized to quantify the leakage of bacterial DNA nucleic acid and protein after intervention with 3 and 6 mg/mL lavender essential oil, and the leakage of bacterial potassium ion was measured by potassium ion test kit. Proteomics technology combined with bio-informatics were applied to explore the action mechanism of lavender essential oil against multi-drug resistant Acinetobacter baumannii.

The MIC and MBC of lavender essential oil were both 6 mg/mL, which could kill almost all multi-drug resistant Acinetobacter baumannii at the time point of 120 min, and showed an obvious dose- and time-dependent manner. The overall animal model evaluation showed that both 3 and 6 mg/mL lavender essential oil could promote wound healing, and the curative effect was obvious. Further studies confirmed that 3 mg/mL lavender essential oil had a certain biofilm inhibitory effect on multi-drug resistant Acinetobacter baumannii, and 6 mg/mL also had a certain biofilm clearance effect under the same conditions. Meanwhile, when incubated at 37 ℃ for 1 h, the dose of 3 mg/mL could increase the leakage of DNA nucleic acid and protein, and significantly promote the efflux of potassium ions. Proteomic analysis suggested that the antibacterial effect of lavender essential oil may be related to affecting the oxidorereductase activity and cell metabolic process of multi-drug resistant Acinetobacter baumannii, and interfering with the biosynthesis of cell wall/membrane/envelope and other structures.

Lavender essential oil at 3 mg/mL can play an antibacterial effect against multi-drug resistant Acinetobacter baumannii, and its mechanism may be related to the destruction of bacterial biofilm and interference with bacterial metabolism.