The antibacterial effect mechanisms of Laurus nobilis extracts on carbapenem-resistant Acinetobacter baumanii isolates

Carbapenem-resistant Acinetobacter baumannii infections are becoming increasingly difficult to treat. Thus, this paper focused on identification of carbapenemase genes in carbapenem-resistant A. baumanii isolates, determining the antibacterial activities of Laurus nobilis L. leaves extracts in both carbapenem-sensitive and resistant strains, and comparing MIC values in strains with various carbapenemase genotypes. Besides, the components of Laurus nobilis extracts and the theoretical calculation of the antibacterial effect mechanisms of Laurus nobilis extracts on A. baumanii isolates were investigated. The MIC value of Laurus nobilis extracts was found to be 250 μg/ml in A. baumanii isolates carrying one or two carbepenemase genes, while the MIC value was found to be 500 μg/ml in strains carrying three or more carbapenemase genes. The extracts of Laurus nobilis had the highest concentration of rutin, followed by ferulic acid. The interaction of the major component of the extract, rutin, with OXA-51 was explored by molecular docking to demonstrate its binding potential. Its interaction was then compared to the interaction of a standard drug (doripenem). The binding potential of rutin was found to be slightly higher than that of doripenem that reflected the limited activity of the extract on the carbapenem-resistant strains. Consequently, new treatment drugs have needed to limit the spread of carbapenem-resistant A. baumannii.