Resistant phenotype and genotype of extended spectrum β-lactamase(ESBLs) produced by Escherichia coli iso1ated from urinary infection in Guangzhou area

Objective To study the resistant phenotype and genotype of extended spectrum β-lactamase(ESBLs) produced by Escherichia coli isolated from urinary infections in Guangzhou.Methods The organisms of clinical infection were identified by automatic microbial system(Vitek) and the bacterial susceptibility was tested by Kirby-Bauer(K-B) method as described in NCCLS.ESBLs was detected by disk diffusion confirmatory test and CTX-M or SHV genotype of ESBLs were determined by specific PCR.Results Of the tested E.coli 33.4% produced ESBLs.Of the 208 ESBLs-producing strains 112 (53.8%) expressed CTX-M genotype of β-lactamase and 43 ( 20.7%) expressed SHV genotype.The resistant rates of ESBLs-producing isolates against penicillins,ciprofloxacin and the third generation cephalosporins were from 84.1% to 97.6%.When the lactamase inhibitors,tazobactam and clavulanic acid,were added for combined administration the resistant rates decreased obviously.Conclusion It was showed in this study that E.coli produced ESBLs was multi-resistance and CTX-M-type were the predominant genotypes of ESBLs in urinary infections of Guangzhou area.