INTRODUCTIONEndogenesis infection plays an important role innosocomial infection.By studying progress ofbacteria translocation from intestinal tract,theconcept of gut-origin infection has been acceptedgradually.Because of no ideal tracing method,there were some controversies.In order to solve theproblem,the PUC19 plasmid vector tracing method INTRODUCTIONEndogenesis infection plays an important role innosocomial infection. By studying progress of bacterium translocation from intestinal tract, theconcept of gut-origin infection has been acceptedgradually.Because of no ideal tracing method, there were some controversies.In order to solve theproblem, the PUC19cophory vector tracing method