Abstract: Objective　To investigate the distribution and prevalence characteristics of extended-spectrum beta-lactamases (ESBLs) and plasmidmediated AmpC genes among Pseudomonas aeruginosa, and provide the reference for monitoring the drug resistance.  Methods　Retrospective survey was performed to get the information of the distribution and resistance of Pseudomonas aeruginosa during 5 years. A total of 169 isolates were collected at the same period of each year. Polymerase chain reaction (PCR) was used to detect the genes of betalactamases including TEM，SHV，VEB，PER，GES，TLA，IBC，CTXM and OXA and the AmpC genes， and the homology of the isolates was identified by the pulsedfield gel electrophoresis (PFGE).  Results　Most isolates were from respiratory tract specimens (sputum) which accounted for 75.7%. A high resistance rate of compound sulfamethoxazole and ceftriaxone among Pseudomonas aeruginosa were identified， which was up to 91.9% and 91.7%. The resistance rates of ceftazidime， imipenem， levofloxacin， ciprofloxacin and amikacin were 46.7%， 38.2%， 30.2%， 28.3% and 5.0%， respectively . Among the 169 isolates, the production genes of betalactamase TEM, CTXM, OXA and GES and AmpC were 49.7% (84 isolates) and 13.6% (23 isolates)， respectively. PFGE showed that there were 3 isolates of Pseudomonas aeruginosa with homology and crosstransmission.  Conclusions　The prevalence of ESBLs and AmpC among Pseudomonas aeruginosa is high. They are mostly multiresistant isolates, and that also exists the phenomenon of the crosstransmission.

Key words: Pseudomonas aeruginosa, Extended-spectrum beta-lactamase, AmpC beta-lactamase, Plasmid, Pulsed-field gel electrophoresis