Abstract: ObjectiveTo study the etiological analysis and molecular typing and traceability of Vibrio Parahaemolyticus isolated from a food poisoning event.MethodsAccording to "National food safety standard for food microbiological test: Vibrio Parahaemolyticus ” GB 4789.7-2013, specimens from the patients' stool, anal swabs and suspicious food in a food poisoning event were tested for Vibrio Parahaemolyticus. The strains isolated were tested for ToxR by real-time fluorescence PCR, and then the virulence gene of thermolabile hemolysin(tlh), thermostable direct hemolysin(tlh) and thermostable related hemolysin(trh) were tested by using multiplex fluorescent PCR. Electrophoresis fingerprints were obtained by pulsed field gel electrophoresis(PFGE) technique and the clustering analysis was performed by BioNumerics software.ResultsSix strains of Vibrio Parahaemolyticus were isolated from 4 patients' stool/anal swabs and 2 suspicious food. The serotypes were O1:KUT, O1:KUT, O3K6, O4:KUT, OUT:KIII, and O3:KUT, respectively. The specific ToxR gene was amplified from 6 strains of Vibrio Parahaemolyticus, all of which were positive for tlh gene. The 4 strains isolated from patient's stool/anal swabs were positive for the tdh virulence genes. One of 2 strains from the suspicious food was positive for tdh virulence gene. All strains were negative for trh virulence gene. Cluster analysis showed that the similarity of the strains was from 62.3% to 100.0%. The finger prints of strains isolated from suspicious food were different from those of strains from the specimens of the patients. Hence, they were different strains. The strains from patients with the same serotype were homologous in cloning. The strains belonging to different serotypes were different clones.ConclusionThe food poisoning event was caused by the mixed infection of different clones of Vibrio Parahaemolyticus, carrying the tdh virulence genes, with serotypes of O1, O3, and O4.