Objective To establish a method of knocking out drug-resistant genes on plasmid contained by clinical Klebsiella pneumonia drug-resistant isolates. Methods Polymerase chain reaction( PCR) was used to amplify the upstream and downstream fragments of target gene blaKPC-2of the test isolates and hygromycin resistance gene fragments on plasmid pMQ300,respectively. Gene splicing by overlap extension polymerase chain reaction( SOE-PCR) was used to construct the fusion fragments,and apramycin resistance lambda red...