Laboratory detection of food poisoning caused by Vibrio parahaemolyticus

Objective To understand the serotypes, virulence genes and molecular types of Vibrio parahaemolyticus causing a food poisoning event and provide evidence for the infection source identification. Methods Serotypes, three genes (tlh,tdh,tdh) of V. parahaemolyticus strains were detected by serum agglutination and multiplex polymerase chain reaction (PCR) respectively. The molecular types were detected by enterobacterial repetitive intergenic consensus sequence (ERIC) PCR. Results O3:K6 (33.3%) was the predominant serogroup. All V. parahaemolyticus strains were positive for tlh gene and negative for trh gene. Totally 66.7% of V. parahaemolyticus strains were positive for tdh gene, all O3:K6 serogroup strains were positive for tdh gene. Three clone clusters were typed by ERIC PCR. E1 clone cluster included 4 serogroup O1 strain, 2 serogroup O2 strains, 1 serogroup O4 strain and 1 serogroup O5 strain. E2 clone cluster included 3 serogroup O1 strains, 2 serogroup O5 strains, 1 serogroup O2 strain, 1 serogroup O4 strain and 1 serogroup O10 strain. E3 clone cluster included 8 serogroup O3 strains. Conclusion The food poisoning was caused by several serogroups of V. parahaemolyticus. O3:K6 was the major serogroup, which were isolated from food and patient samples and in same clone cluster by ERIC PCR. E1 and E2 clone clusters included all serogroups except O3. The laboratory detection indicated that the food poisoning was associated with the contamination of foods by several serogroups of V. parahaemolyticus.