Abstract: To explore the antibacterial effects of flavonoids on resistant Acinetobacter baumannii.In this research,the antibacterial effects and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 40 kinds of traditional Chinese medicine flavonoids on three strains of Acinetobacter baumannii were tested by micro broth dilution method in vitro.Biofilm-forming ability was detected by crystal violet staining assay.The antimicrobial tests of flavonoids combined with Cefoperazone/sulbactam were also conducted.The flavonoids showed antibacterial effect in vitro at different degrees on Acinetobacter baumannii.Most of them have faint inhibitions,and their MICs were 0.5 mg/mL.Baicalein and wogonoside have significant antibacterial effect,of which the mean MICs were 0.062 5 and 0.125 mg/mL,respectively.Meanwhile,baicalein also showed obvious inhibitory effect on biofilm formation.Besides,inhibitory effect of baicalein combined with Cefoperazone /sulbactam on resistant Acinetobacter baumannii reduced compared with single baicalein or cefoperazone /sulbactam.In summary,baicalein has a good antibacterial effect on drug resistant Acinetobacter baumannii,which provides new ideas and directions for the treatment of resistant Acinetobacter baumannii infection.

Key words: resistant Acinetobacter baumannii, traditional Chinese medicine flavonoids, antibacterial effect, biofilm