Objective To investigate the antibiotic resistance of extended-spectrum β-lactamases (ESBLs)-producing bacteria,and the risk factors for patients with hospital-acquired lower respiratory tract infections caused by these bacteria.Methods The clinical data of 80 cases of hospital-acquired lower respiratory tract infections caused by ESBLs + bacteria in the People's Hospital of Qingtian in Zhejiang Province from July 2008 to December 2011 were collected; and 160 cases of nosocomial infection caused by ESBLs- bacteria were randomly selected as controls.Univariate analysis and multivariate logistic regression were used to analyze the risk factors for ESBLs + bacteria infection.The resistance of sixteen antibiotics was detected by K-B method.Results Univariate analysis revealed that the risk factors for nosocomial lower respirator tract infection caused by ESBLs+ bacteria were hospitalization ≥ 10 d,readmission to hospital,oxygen inhalation,invasive operations,using antacid ＞ 7 d,using glucocorticoids ＞ 7 d,using immunosuppressant ＞ 7 d,using third-generation cephalosporins,using fluoroquinolone antibacterials,and the combined use of antibiotics≥3 d.Multivariate logistic regression analysis identified five independent risk faetors:oxygen inhalation (OR =8.613,95％ CI:1.870-39.659),invasive operations (OR =5.900,95％CI:1.885-18.467),using third-generation cephalosporins (OR =7.465,95％ CI:2.364-23.578),using fluoroquinolone antibacterials (OR =4.481,95％ CI:1.197-16.781) and combined use of antibiotics≥3 d (OR =5.346,95％ CI:1.717-16.643).ESBLs + Escherichia coli and Klebsiella pneumoniae strains were sensitive to imipenem,meropenem,cefoperazone /sulbactam and piperacillin/tazobactam (with the resistance rates lower than 30.00％),but were highly resistant to most β-lactam,aminoglycoside,fluoroquinolone and sulfonamide antibacterials.Conclusion ESBLs + isolates were highly resistant to most antibacterials,and hospital-acquired lower respiratory tract infections with ESBLs+ bacteria are mainly related with invasive operations and the use of antibiotics.