Vibrio parahaemolyticus Strains of Pandemic Serotypes Identified from Clinical and Environmental Samples from Jiangsu, China.

Jingjiao Li,Feng Xue,Yuan Jiang,Guoxiang Chao,Baoguang Li,Xiaoping Zhang,Zhenquan Yang,Dexin Zeng

doi:10.3389/fmicb.2016.00787

Abstract

Vibrio parahaemolyticus has emerged as a major foodborne pathogen in China, Japan, Thailand, and other Asian countries. In this study, 72 strains of V. parahaemolyticus were isolated from clinical and environmental samples between 2006 and 2014 in Jiangsu, China. The serotypes and six virulence genes including thermostable direct hemolysin (TDR) and TDR-related hemolysin (TRH) genes were assessed among the isolates. Twenty five serotypes were identified and O3:K6 was one of the dominant serotypes. The genetic diversity was assessed by multilocus sequence typing (MLST) analysis, and 48 sequence types (STs) were found, suggesting this V. parahaemolyticus group is widely dispersed and undergoing rapid evolution. A total of 25 strains of pandemic serotypes such as O3:K6, O5:K17, and O1:KUT were identified. It is worth noting that the pandemic serotypes were not exclusively identified from clinical samples, rather, nine strains were also isolated from environmental samples; and some of these strains harbored several virulence genes, which may render those strains pathogenicity potential. Therefore, the emergence of these “environmental” pandemic V. parahaemolyticus strains may poses a new threat to the public health in China. Furthermore, six novel serotypes and 34 novel STs were identified among the 72 isolates, indicating that V. parahaemolyticus were widely distributed and fast evolving in the environment in Jiangsu, China. The findings of this study provide new insight into the phylogenic relationship between V. parahaemolyticus strains of pandemic serotypes from clinical and environmental sources and enhance the MLST database; and our proposed possible O- and K- antigen evolving paths of V. parahaemolyticus may help understand how the serotypes of this dispersed bacterial population evolve.

Highlights

Vibrio parahaemolyticus is a Gram-negative, halophilic bacterium that inhabits global coastal waters and rivers, and in seafood, such as fish and shellfish (Kelly and Stroh, 1988)
Based on the epidemiological surveillance data from countries in Southeast Asia, V. parahaemolyticus infections have become a majority of foodborne pathogen (Pan et al, 1997; Wong et al, 1999; Obata et al, 2001; Liu et al, 2004; Cho et al, 2008; Letchumanan et al, 2014)
multilocus sequence typing (MLST) analysis confirmed that O3:K6 and its derivatives belong to the same genetic lineage (Chowdhury et al, 2000, 2004; Matsumoto et al, 2000)

Summary

Introduction

Vibrio parahaemolyticus is a Gram-negative, halophilic bacterium that inhabits global coastal waters and rivers, and in seafood, such as fish and shellfish (Kelly and Stroh, 1988). V. parahaemolyticus was initially discovered in 1950 (Parveen et al, 2008; Letchumanan et al, 2015b). V. parahaemolyticus can cause three major clinical syndromes: gastroenteritis, wound infections, and septicemia (Daniels et al, 2000), and is considered as the causative agent of the most prevalent food poisoning in Asia since the outbreak in 1959 (Miyamoto et al, 1962). V. parahaemolyticus infections usually resulted from consumption of raw or undercooked seafood, mostly causing gastroenteritis (Miyamoto et al, 1969). V. parahaemolyticus has been identified as a major foodborne pathogen in food poisoning incidents in China, raising public health concern (Ma et al, 2014; Zhang et al, 2015)

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