AmpC β-lactamases of the Klebsiella pneumoniae were detected and their resistance was analyzed

Objectives The AmpC β-lactamases and extended-spectrum β-lactamases(ESBLs)had been detected in Klebsiella pneumoniae,and their resistance was analyzed.So their main mechanism of resistance was revealed,which will help us medicate reasonably in clinic.Methods Adopting a modified three dimensional extract test,which was used to detect phenotypically isolates which harbor depressed AmpC β-lactamases and production of ESBLs.ln the test,the surface of a Mueller-Hinton agar plate was inoculated with E.coli ATCC 25922 as described in NCCLS for disk diffusion method.Results The rate of AmpC β-lactamases was 2.5% and the rate of ESBLs was 45.5%,and the rate of AmpC+ESBLs was 0.8% in 121 strains of Klebsiella pneumoniae.The resistant rate of penicillins,cephlosporins,cephamycins,monobactams,fluoroquinolones,sulfanilanides and some β-lactam/β-lactam inhibitor combinations was from 50%~100%.The resistant rate of Piperacillin/tazobactam was less than 50%,and the resistance of imipenam had not been detected.Conclusions ESBLs and AmpC β-lactamases are the most important reistant mechanisms of Klebsiella Pneumoniae to cephalosporins.Producing ESBLs and AmpC β-lactamases Klebsiella pneumoniae were highly resistant to more antibiotics.β-lactamases should be detected timely and treated carefully.