Abstract: OBJECTIVE To investigate the distributions of OXA,AdeABC,CarO genes and biofilm in clinical imipenem-resistant and imipenem-sensitive Acinetobacter baumannii isolates,so as to further explore the imipenemresistant mechanism.METHODS A total of 106 strains of imipenem-resistant and 102 strains of imipenem-sensitive clinical AB strains were isolated from the General Hospital of Ningxia Medical University from Nov.2014 to Oct.2015.The drug-resistant genes OXA,AdeABC,and CarO were detected with PCR technology,and biofilm formation and quantitative experiment were carried out with microtiter plate method.RESULTS The detection rates of OXA-23 gene were respectively 99.1% and 2.9%in imipenem-resistant and imipenem-sensitive strains,with significant difference（P＜0.05）.The OXA-24 gene was found in one imipenem-resistant isolate.The OXA-51 gene was detected in all tested clinical isolates,while the OXA-58 gene was not detected in all examined strains.The distribution of AdeABC efflux pump genes showed a significant variation between resistant and sensitive isolates.CONCLUSION The OXA-23 gene was the most prevalent gene in these imipenem-resistant strains,and was the most important OXA subtype of imipenem-resistant strains in hospital.The majority of these examined A.baumannii infection in clinic was related to the formation of biofilm,which can provide scientific basis for clinical treatment.