Abstract: To explore the role of efflux pump in resistance to antibacterial drugs and the relationship between the extended-spectrum β-lactamase and efflux pump in Escherichia coli.Activities of 10 antibacterial drugs were detected by using 2-fold agar dilution method with or without efflux pump inhibitors,carbonylcyanidem chlorophenylh-dra—zone(CCCP) and Reserpine,in E.coli.After treated with efflux pump inhibitor,Reserpine,the MICs of the positive ESBLs strains decreased on Ampicillin,Ceftriaxone,Cefotaxime and Fosfomycin.The decline in the antimicrobial resistance ranged from 7.7% to 30.7%.But the MICs declined on Ceftriaxone,Cefotaxime,Amikacin and Fosfomycin in the positive ESBLs strains with the addition of CCCP.The decline in the antimicrobial resistance ranged from 15.4% to 46.12%.The rate,which associated with the positive efflux pump,had statistically significant differences in the positive ESBLs strains as compared to Reserpine with CCCP.However,it had no statistically significant differences in the negative ESBLs bacteria.CCCP and Reserpine differed greatly on screening the efflux pump.The rate of postive efflux pump in the positive ESBLs strain was significantly higher than that in the negative ones.There appeared a correlation between the ESBLs and efflux pump.