The Serotype,Virulence Genes and Molecular Type of Vibrio Parahaemolyticus in Sichuan Province in 2009

Objective To understand the Vibrio parahaemolyticus strains' serotype distribution,pathogenicity and molecular characteristics isolated from food poisoning outbreak and food safety surveillance in Sichuan region in 2009,so as to support the work of outbreak forecast and policy-making on Vibrio parahaemolyticus disease control.Methods By using the slide serum agglutination method to detect the serotypes of the Vibrio parahaemolyticus strains isolated from food poisoning outbreaks and routine surveillance on food safety in 2009 and by using PCR method to detected thermostable direct hemolysin gene(TDH) and thermostable direct hemolysin gene(TRH).The mice were conducted intraperitoneal injection of virulence experiments and with pulsed-field gel electrophoresis(PFGE) and were analyzed with aspect of molecular typing.Results There were five serogroups in the 40 strains and they were isolated from outbreaks belonged to the O3 and O4 groups;the main serogroup of the surveillance food isolated strains was O1,with a rate of 43.75%(7/16).There were multiple serotypes isolated strains in the same outbreaks;all strains TRH gene were negative and 20 of them carried the TDH virulence gene.The virulence experiment showed that the strains carrying TDH virulence gene and the strains carried no virulence genes were virulence.A total of 29 banding type were isolated from same outbreak by PFGE typing.Conclusion There is no apparent relationship between the Vibrio parahaemolyticus strains isolated from food and the outbreaks;the serotype and PFGE type of Vibrio parahaemolyticus strains isolated from food were diverse.The relationship between the various strains and the outbreaks needs to be confirmed.