Abstract: OBJECTIVE To understand the predisposing factors for lower respiratory tract infections caused by multidrug-resistant gram-negative bacteria（MDRB）in patients with severe chronic obstructive pulmonary disease（COPD）and analyze the distribution of pathogens so as to provide guidance for prevention and control of emergence of the multidrug-resistant strains.METHODS A total of 277 severe COPD patients with gram-negative bacteria lower respiratory tract infections who were hospitalized from Jan 2013 to Nov 2015 were enrolled in the study.The incidence of MDRB infection,predisposing factors,and distribution of pathogens were observed.RESULTS The incidence of MDRB infection was 28.52%in the patients with severe COPD.The predisposing factors included the hospital-acquired infection,complication with diabetic mellitus,hypoalbuminemia,invasive operations,third generation cephalosporins,use of fluoroquinolones,and combined use of antibiotics no less than 3days.The Acinetobacter baumannii,Pseudomonas aeruginosa,Klebsiella pneumoniae,and Escherichia coli were dominant among the 79 strains of multidrug-resistant gram-negative bacteria.CONCLUSION It is necessary to strengthen the surveillance and control of the pathogens causing the lower respiratory tract infections in the patients with severe COPD and reasonably use antibiotics based on the results of the drug susceptibility testing so as to prevent the emergence of the drug-resistant strains.