Abstract: OBJECTIVE To explore the drug resistance of multidrug-resistant Acinetobacter baumannii and β-lactamases related genes and analyze the drug resistance mechanisms to β-lactams so as to provide guidance for reasonable clinical use of antibiotics. METHODS The specimens were collected from the patients with clinical infectious diseases who were treated in Shanxi Dayi Hospital from Sep 2013 to Mar 2014, then the isolated strains were identified by using VITEK-2 system, the drug susceptibility testing was performed, the extended-spectrum β-lactamases (ESBLs) were detected by means of K-B disc diffusion method, the AmpC enzyme-producing strains were screened out, and the β-lactamases genes were analyzed with the use of PCR and sequence analysis method. RESULTS Of 55 strains of A.baumannii, 41 were the multidrug-resistant A.baumannii.The drug resistance rate of the multidrug-resistant A.baumannii to β-lactams or β-lactamases inhibitors (ampicillin-sulbactam, piperacillin-tazobactam) varied from 87.8% to 90.2%; the drug resistance rates to other β-lactams, aminoglycosides, and fluoroquinolones varied from 85.4% to 100.0%.Of the 41 strains of multidrug-resistant A.baumannii, 27 ESBLs-producing strains were detected positive, with the positive rate of 65.9%.Totally 30 AmpC enzyme-producing strains were screened out, with the positive rate of 73.2%.The TEM gene was detected positive in 25 ESBLs-producing strains, with the positive rate of 92.6%; the ampC gene was detected positive in 8 AmpC enzyme-producing strains, with the positive rate of 26.7%. CONCLUSION A.baumannii strains isolated from Shanxi Dayi Hospital are multidrug-resistant, and the drug resistance to β-lactams is closely associated with the TEM and ampC genes.