Objective To observe the expressions of efflux pump gene cluster adeAB in acinetobacter baumannii isolated from the burn patients and the expression changes of its upstream regulatory genes adeR and adeS and determine the influence of those genes on drug resistance of acinetobacter baumannii.Methods Nine drug-resistant strains and nine sensitive strains of acinetobacter baumannii isolated from the burn patients treated between June 2012 and March 2013 were used.After strain identification using 16SrDNA sequencing,acinetobacter baumannii standard strain ATCC19606 was employed as the control.mRNA expressions of efllux pump genes adeA and adeB and their upstream regulatory genes adeR and adeS were detected by real-time quantitative PCR.Results (1) adeA and adeB genes presented higher expressions in drug-resistant strains (3.71 ±0.95,76.16 ± 8.75) than in sensitive strains (0.92 ± 0.94,0.72 ± 0.78) (F =38.71,663.65 respectively,both P ＜ 0.05).(2) adeS and adeR genes showed higher expressions in drug resistant strains (18.02 ± 6.71,3.02 ± 2.69) than in sensitive strains (1.64±1.51,0.76±0.61) (F =51.04,5.57 respectively,bothP＜0.05).Conclusions The over-expression of efflux pump gene cluster adeAB induced by the expression alteration of its upstream regulatory genes adeR and adeS is closely associated with the drug resistance of acinetobacter baumannii in the burn patient.Besides,the regulatory genes may depend on adeS to sense the nosocomial environment condition,activate or inactivate adeR and hence regulate efflux pump expression.