Abstract: AIM: To evaluate the drug fast mecha-nism of bacteria gowing in biofilm，and to provide the theoretical basis for selecting antimicrobial agents in clinic. METHODS: The model of klebsiella pneu-moniae bacterial biofilm were built up with the modifed flat-board method and identified with the method stain-ing with AgNO₃ and confocal scanning laser microscopy. The ESBLs and AmpC were detected by improved three dimensional test. RESULTS: The detection rates of AmpC，ESBLs and AmpC plus ESBLs in isolated klebsiella pneumoniae were 2.5%(1/40)，20.0%(8/40) and 2.5%(1/40),whereas the detection rates of AmpC，ESBLs and AmpC plus ESBLs in biofilm kleb-siella pneumoniae were 20.0%(840)，45.0%(18/40)and 22.5%(940). The resistance rates of the biofilm klebsiella pneumoniae producting AmpC and ESBLs to eight kinds of antibiotics were higher. CONCLUSION: The synergetic effect of the formation of biofilm and the pioduction of ESBLs and AmpC is one of the main reasons that klebsiella pneumoniae resists antibiotics.

Key words: klebsiella pneumoniae, biofilm, ESBL, AmpC