ObjectiveTo investigate the causes of a healthcareassociated lower respiratory tract infection(HALRTI) outbreak due to Enterobacter cloacae(E. cloacae), and provide basis for clinical prevention and control of HAI. MethodsEpidemiological data of patients with E. cloacae HALRTI following bronchoalveolar lavage(BAL) in the departments of respiratory disease and thoracic surgery of a hospital were collected, antimicrobial resistance analysis on isolated pathogens from patients and environment was performed, pulsedfield gel electrophoresis (PFGE) was used for genotyping. ResultsOn March 8-16, 2013, a total of 15 patients underwent BAL in the fiberobronchoscopy room in the departments of respiratory disease and thoracic surgery of a hospital, 13 of whom developed E. cloacae LRTI, 4 cases were community-associated infection (the initial case was included), the other 9 cases were HAI; 8 environmental specimens were detected 2 strains of E. cloacae, the strains were from vacuum suction joint of fiberbronchoscope and scissors used for trimming disposable controllable sputum suction pipeline. 15 strains of E. cloacae from environment and patients were screened by antimicrobial susceptibility testing, 11 strains were with similar antimicrobial susceptibility testing result, 2 of which were environmental strains, 6 were from inpatients, and 3 were from patients in community. PFGE typing of 11 strains revealed that there were 8 strains with the same genotype, 6 of which were from patients in department of thoracic surgery, 2 were from vacuum suction joint of fiberbronchoscope and scissors used for disposable controllable sputum suction pipeline; the other 3 strains were of the same genotype, and from departments of respiratory disease and thoracic surgery. ConclusionThis outbreak is due to contamination of bronchofibroscope by the same E. cloacae strain, the strain is susceptible to the clinic commonly used antimicrobial agents, such events should be paid attention in clinic, the key to control infection is to take necessary measures for cutting off the spread of the epidemic.