Abstract:To analyze the homology of E. coli O157 strains from several regions of Jiangsu province in these years. Polymerase Chain Reaction-restriction fragment length polymorphism (PCR-RFLP) was used for the molecular subtyping of one hundred and eight E. coli O157 strains, which showed distributional diversity in different areas and years. EcoRV restriction patterns were divided into ten types named JS01-JS10. 64.9% of all the E. coli O157 belonged to JS01, which was very similar to JS02 in digest pattern. Almost half of 12 strains named JS03 and JS04 were isolated from human samples. Most of the EcoRV restriction patterns were observed in 1999, whereas strains from Tongshan had great variety. The strains tested were mainly grouped according to cultivars origins, while pathogenicity differed in restriction patterns. From the above observations, it is evident that PCR-RFLP is easy and repeatable, providing a brand-new method for epidemiological study of E. coli O157.