Abstract: Objective: To investigate DHA plasmid-mediated AmpC β-lactamases in the clinical isolation of Pseudomonas aeruginosa(Pa) from patients in Huaibei Miner's General Hospital.Methods: Thirty-six Pa isolated from clinical specimens were collected and analyzed drug-resistance to clinical common antibiotics with K-B method,and detected the resistance phenotypes by modified three-dimensional test.After extraction of genomic DNA,DHA-1 gene was amplified by polymerase chain reaction(PCR) and sequenced.Homology analysis of these sequences was carried out by compared with DHA genes of enterobacteriaceae in gene bank.Results: DHA-1 gene was amplified by PCR in 69.4%(25/36) Pa isolations.The resistant rate of 25 Pa to 10 types of antibiotics was more than 50%,and ERIC-PCR analysis was shown DHA-1 was prevailed in the same or different departments in our hospital.Conclusions: The detection rate of DHA-1 is much higher than that in other regions;Pa isolated with DHA-1 gene showed powerful activities with resistance to cephalosporin and monocyclic lactam antibiotics.The prevalence of Pa in the same or different departments should be noted seriously.