Research on ESBLs and AmpC beta-lactamase genes in Enterobacter cloacae and their epidemiology

OBJECTIVE To investigate the distribution and drug resistance of AmpC beta-lactamases and ESBLs-producing Enterobacter cloacae from 2008 to 2010.METHODS The modified three dimensional test was used to detect AmpC beta-lactamases.ESBLs were detected by using disk diffusion phenotypic confirmatory test.And the polymerase chain reaction(PCR) was adopted to test the genotype of AmpC beta-lactamases and ESBLs.Broth dilution method was employed to analyze the bacterial resistance,and bonding plasmid test was carried out to analyze the spread of resistant genes.RESULTS The drug resistant rates of ESBLs and AmpC-producing isolates to the third,fourth generation of cephalosporins,or the antibiotics containing enzyme inhibitor were higher than 50.0%;there were 45 AmpC-producing strains by the method of modified three-dimensional experiment and 14 ESBLs-producing were identified via confirmatory test;there were 25 ESBLs-positive strains and 38 AmpC-positive strains,TEM-1 as well as MIR-3 was the main genotype,followed by CTX-M-3 and DHA-1,there were 2 SHV-11 ESBLs-producing isolates,no strains that produced AmpC genotypes of CIT,MOX,FOX and ACC were detected,five isolates were successed in conjugation experiments.CONCLUSION Drug resistance of E.cloacae which mainly carries TEM-1 ESBLs and MIR-3 AmpC beta-lactamase is severe.It is necessary to take effective measures to prevent the dissemination and prevalence of multidrug-resistant isolates.