Objective To study the epidemic trend,homology and the mechanism of drug resistance of Acinetobacter baumannii(MDR-Aba) in Intensive Care Units(ICU) of the hospital in which the authors served,so as to offer a reference for clinical treatment and efficient preveation of iatrogenic infection.Methods Fourteen consecutive MDR-Aba isolates were collected from ICU of General Hospital of Shenyang Command from June to Dec.2008.Drug sensitivity of these isolates to 14 antibiotic drugs,including β-lactam,aminoglycoside and fluoroquinolone,etc,was examined by K-B test.Pulsed-field gel electrophoresis(PFGE) was employed to detect the homology of Acinetobacter baumannii,and cluster analysis was carried out with GelCompar 6.3 software to group the isolated MDR-Aba.PCR was performed to amplify the genes related to drug resistance from these isolates,and the results were identified by sequencing.Results All the 14 isolates were highly resistant to cephalosporins,carbapenems,aminoglycoside and fluoroquinolone,while some of them retained susceptibility to cefoperazone/sulbactam,and most of the strains showed susceptibility to minocycline in vitro.All isolates belonged to a same PFGE pulsotype,which may be divided into 2 subtypes as Type A1(n=10) and Type A2(n=4).OXA-23-like,OXA-51-like and Int I genes were detected by PCR in all isolates.Conclusion All MDR-Aba isolates collected basically belong to the same lineom.The mechanism of antibiotic resistance may be closely related to these genes such as OXA-23-like,OXA-51-like and Int I.