Objective      To investigate the epidemiological characteristics of nosocomial infection by Acinetobacter baumannii (A. baumannii) and its antibiotic resistance change in our hospital

and to analyze the reason for A. baumannii outbreak and prevalence.     Methods      Five-hundred and ninety-one strains of A. baumannii isolated from our hospital from 2006 to 2009 were selected for a systematic study on A. baumannii infection distribution and change of its antibiotic resistance spectrum. The homology of 102 strains of Pandrug-resistant A. baumannii (PDR-Ab) including A. baumannii resistant to carbapenems in 2009 were studied using PFGE

and antimicrobial susceptibility test was performed using agar dilution method according to the NCCLS guidelines for MIC testing.     Results      The infection of A. baumannii in our hospital mainly occurred in pneumology department

intensive care units (ICU)

neurology department

cardiac surgery and neurosurgery department. The drug resistance rate of A. baumannii to common antibiotics increased year by year. The resistance rates to minocycline

doxycycline and polymyxin B were the lowest (43.7%

32.9%

2.5%

respectively)

while the resistance rate to carbapenems raised fast

accompanied by a dramatically increased dosage of carbapenems. PFGE results showed that an outbreak of A/B clone strains of A. baumannii in ICU and neurology department.     Conclusion      Unreasonable use of Carbapenems and prevalence of A. baumannii clone strains result in an increasing infection rate of hospital-acquired PDR-Ab. It is necessary to strengthen the control of nosocomial infection and reasonable antibiotics administration to improve the curative effect and reduce A. baumannii infection.