Background:Carbapenem-resistant Acinetobacter baumannii (CRAB) have been a challenging conc of health-care associated infections.The aim of the current study was to investigate the molecular epidemiology and clonal dissemination of CRAB isolates in a Chinese teaching hospital.Methods:Non-duplicate clinical A.baumannii isolates were collected from inpatients,and we measured the minimal inhibitory concentrations to determine antimicrobial susceptibility.Polymerase chain reaction (PCR) and sequencing were performed to detect carbapenem-resistance genes and occurrence of transposons among CRAB isolates.Moreover,the genetic diversity among isolates and clonal dissemination were determined by repetitive element PCR-mediated DNA fingerprinting (rep-PCR) and multilocus sequence typing (MLST).Results:A total of 67 CRAB isolates displayed resistance to most of the antibiotics tested in this study,except tigecycline.We detected blaOXA-23,blaOXA-51,blaOXA-58,and blaVIM genes in 94.0 ％,100.0 ％,1.5 ％,and 80.6 ％ of the CRAB isolates,respectively.Nevertheless,74.6％ of the CRAB isolates co-harbored the blaOXA-23 and blaVIM.Only one type of transposons was detected:Tn2008 (79.1％,53/67).Although 12 distinctive types (A-L) were determined (primarily A type) ST195 was the most prevalent sequence type (ST).ST368,ST210,ST90,ST829,and ST136 were also detected,and all belonged to clonal complex 208 (CC208)and global complex 2 (GC2).Conclusion:The blaOXA-23 and blaVIM genes contributed to the resistance among CRAB isolates collected in our study.Notably,most of the CRAB strains co-harbored blaOXA-23 and blavVIM genes,as well as Tn2008,which could contribute to clonal dissemination.The prevalence of such organisms may underlie hospital acquired infections.