Abstract: Objective To analyze the resistant pattern and the extended-spectrum β-lactamase genotypes of clinical isolates and homologous analysis of Shigella flexneri in Tangshan. Methods Susceptibility testing was perfomed by K-B disk diffusion method ESBLs confirmation experiment. The MICs against ESBLs-producting were determined by trace broth dilution method..PCR method was employed to detect the genotypes of ESBLs producing strains. The PCR products were analyzed by DNA sequencing. Through the variable number tandem repeats (VNTR) homology analysis. Results ESBLs were idenitified in 44.2%(19/43) of Shigella flexneri isolates. So did MICs. 95~100% of these isolates were susceptible to ceftriaxone, cefotaxime, cefoperazone, Piperacillin, amoxicillin- clavulanate.More than 84% these isolates were susceptible to other antibiotics. The genotypes of these stains included CTX-M-14, CTX-M-3、CTX-M-57 and TEM-1. Homology analysis 19 strains of shigella's blessing is divided into four clones.Conclusions The Shigella flexneri isolates in Tangshan were multi-drug resistant. It is increasing on the third generation cephalosporin antibiotic. The main genotypes of ESBLs were CTX-M-14. The first detected CTX-M-57 genotype.Both genetic-related clones and non-related clones of Shigella flexneri in Tangshan.

Key words: Shigella flexneri, extended-spectrum β-lactamase, genotype, VNTR, Homology