Virulence gene detection and traceability analysis of 4 Vibrio parahaemolyticus food poisoning incidents

Abstract

ObjectiveTo analyze the etiological characteristics of strains isolated from Vibrio parahaemolyticus food poisoning incidents occurred in Zibo in 2019.MethodsSerotyping and virulent genes (tlh, tdh, trh)were detected by real-time fluorescent polymerase chain reaction, antibiotic sensitivity was examined by broth microdilution method and pulsed field gel electrophoresis (PFGE) were applied to Vibrio parahaemolyticus.ResultsThe 9 strains collected from patients were all pandemic O3∶K6, and the virulence genes were tlh+ tdh+ trh-. The 2 strains collected from environmental samples were O8∶K22 and O1∶K32, and the virulence genes were all tlh+ tdh-trh-. All strains were resistant to cefazolin, and partially resistant to ampicillin and trimethoprim/sulfametho-xazole. There were 2 strains even showed multiple resistance to these three antibiotics, while all strains were sensitive to the other antibiotics. The PFGE homology from the same incident was high.ConclusionThe strains collected from patients in the 4 incidents were all pandemic O3∶K6 and the virulence genes were tdh+, some of which showed multi-antibiotic resistance, and the isolates from the same outbreak had high homology suggesting that they had been exposed to the same pollution source. The supervision of pollution sources should be strengthened to reduce the occurrence of foodborne diseases.

Keywords

• vibrio parahaemolyticus
• serotype
• virulence genes
• antibiotic sensitivity
• pulsed field gel electrophoresis