OBJECTIVE To analyze resistance and detect plasmid-mediated AmpC genes in Klebsiella pneumoniae.METHODS The susceptibility of the K.pneumoniae to 13 antibiotics was tested by K-B method.Modified three-dimensional extract test was adopted to detect AmpC lactamases in K.pneumoniae.The genotypes of AmpC lactamases were determined by polymerase chain reaction and sequencing.RESULTS Among the 105 isolates,the rate of extended spectrum ?-lactamases(ESBLs) was 41.90%,the rate of AmpC ?-lactamases was 0.95% strains,and the rate of ESBLs and AmpC ?-lactamases was 2.86%.DNA sequence analysis conformed that AmpC lactamases positive isolates were DHA AmpC gene.The resistance rate to penicillins,cephalosporins,?-lactam/?-lactam inhibitors,monobactams,and fluoroquinolones was very high.The susceptibility rate to imipenem was 100.00%.CONCLUSIONS The plasmid-mediated AmpC gene is present in clinically isolated K.pneumoniae.The resistance can be transferred to homologous or different genera of bacteria.