Characterization and epidemiological analysis of Vibrio parahaemolyticus isolated from different marine products in East China

Vibrio parahaemolyticus is a major foodborne pathogen with a wide distribution in the world that causes economic and public health problems. Here, we isolated 152 V. parahaemolyticus strains from shellfish, shrimp, crab, and snails from 5 provinces in East China, and analyzed the genetic diversity, population structure, and virulence profiles of these isolates. Our results showed that the 152 V. parahaemolyticus strains belong to 84 different sequence types (STs), of which 69 (82.14 %) STs and 60 alleles were newly identified. The thermostable direct hemolysin (TDH) and the TDH-related hemolysin (TRH) were present in 4 V. parahaemolyticus isolates (2.63 %) respectively, while toxRS/new, a distinctive toxRS sequence that was associated with pandemic V. parahaemolyticus strains, is present in 52 isolates (34.21 %). Thereinto, both the ZJ11 and ZJ12 strains measure up to the standard of toxRS/new+, tdh+, and trh-, which was widely used marker for the rapid screening of pandemic strains, and thus these strains may have the risk of infectious outbreaks. In addition, we observed that all the 152 V. parahaemolyticus isolates encode type III secretion systems 1 and type VI secretion system (T6SS) 2, while 119 isolates (78.29 %) of them also contain T6SS1. The genetic relatedness of our isolates to the human V. parahaemolyticus collection was explored, which showed that ST6, ST79, ST162, ST1060, and ST1061 were all identified in both human isolates (7 isolates) uploaded in the PubMLST database and our marine products isolates (7 isolates). Our findings expand the views of the genetic diversity of V. parahaemolyticus and will contribute to understanding the potential risk of the transboundary spread of this bacterium.