Objective:To analyze the epidemic characteristics and gene type of the Extended-Spectrum β-Lactamases(ESBLs)-producing Gram-negative bacterium in Chong-qing area from 2002 to 2004

and investigate its distribution of gene typing and drug resistance.Methods:There were 4022 Gram-negative bacterium isolated in clinic from 2002 to 2004

and they were identified and done the drug sensitivity by the microscan walkaway-4.0.ESBLs-producing strains were detected by K-B method and amplified by PCR.The DNA of 108 chosen ESBLs-producing strains were genotyped by Tripure Isolation Reagent.Results:1468 ESBLs-producing strains were detected.The rates of Escherichia.coli and Klebsiella.pneumoniae were 52.5% and 65.8% respectively.The general positive rate of ESBLs-producing was 58.0%.And the rates in year 2002

2003 and 2004 were 68.2%

56.9% and 50.8% 2002 to 2004 respectively.The result of PCR showed that 3 types of gene typing

TEM

SHV and CTX were detected in 108 chosen ESBLs-producing strainsThe TEM type was the main type in E.coli(56/59)

E.asburiane(12/13)and P.aeruginosa(6/7)while the SHV type was the main type in K.pneumoniae(28/29).TEM type was the main type for year 2002(75%)

both TEM(40%)and SHV(57.1%)for 2003

and TEM for 2004(90.9%)with CTX as infrequent type(3.7%).The resistance rates of ESBLs-producing isolates against penicillins

aztreonam and the third generation cephalosporins were about 56.2%-100%

and almost multi-resistant.Conclusion:The incidence of ESBLs-producing isolates was decreasing by year

and ESBLs-Producing isolates mainly carried TEM and SHV types of β-Lactamases with the TEM one as the major.Their drug resistances were not so good.Those indicated that it is necessany to strengthen the understanding about bacterium resistance and gene type change

administer medicines reasonably to decrease the resistant ones and control the infection in hospital better.