Genotype identification and virulence gene analysis of Shigella flexneri4c subtype in Ma'anshan City

The objective of the present study was to understand the epidemic type of virulence gene and the characteristics of molecular typing in Shigella flexneri4c(F4c) isolates in Ma'anshan city.These strains were isolated and cultured by conventional method and the biochemical characteristics were identified by AMS.PCR was used to detect ipaH,ial,set and sen virulence genes in identified Shigellastrains and pulse-field gel electrophoresis(PFGE) was used in molecular identification.Results demonstrated that the distribution rates of ipaH,ial,set and sen virulence genes among these 76 strains was 100%,97.4%,96.1% and 90.8% respectively and the four virulence genes reacted positively in 67 ShigellaF4c strains.There were five types of virulence gene-carried pattern in this area and was dominated by TypeⅠ.Results of PFGE showed that 100% identical ShigellaF4c strains was minority.The 100% identical strains were appeared in the same generation,while the 91% identical strains were appeared cross generations.Isolates from differential generations did not have the same gene type completely and have no regional relation.It's indicated that these ShigellaF4c isolates in Ma'anshan City carried four virulence genes as ipaH,ial,set and senamong them generally with a main characteristic of strong virulence.Meanwhile,ShigellaF4c is defined as sporadic disease as there is no epidemic sign in this area.