Sero-Prevalence and Genetic Diversity of Pandemic V. parahaemolyticus Strains Occurring at a Global Scale

Abstract

Pandemic Vibrio parahaemolyticus is an emerging public health concern as it has caused numerous gastroenteritis outbreaks worldwide. Currently, the absence of a global overview of the phenotypic and molecular characteristics of pandemic strains restricts our overall understanding of these strains, especially for environmental strains. To generate a global picture of the sero-prevalence and genetic diversity of pandemic V. parahaemolyticus, pandemic isolates from worldwide collections were selected and analyzed in this study. After a thorough analysis, we found that the pandemic isolates represented 49 serotypes, which are widely distributed in 22 countries across four continents (Asia, Europe, America and Africa). All of these serotypes were detected in clinical isolates but only nine in environmental isolates. O3:K6 was the most widely disseminated serotype, followed by O3:KUT, while the others were largely restricted to certain countries. The countries with the most abundant pandemic serotypes were China (26 serotypes), India (24 serotypes), Thailand (15 serotypes) and Vietnam (10 serotypes). Based on MLST analysis, 14 sequence types (STs) were identified among the pandemic strains, nine of which fell within clonal complex (CC) 3. ST3 and ST305 were the only two STs that have been reported in environmental pandemic strains. Pandemic ST3 has caused a wide range of infections in as many as 16 countries. Substantial serotypic diversity was mainly observed among isolates within pandemic ST3, including as many as 12 combinations of O/K serotypes. At the allele level, the dtdS and pntA, two loci that perfectly conserved in CC3, displayed a degree of polymorphism in some pandemic strains. In conclusion, we provide a comprehensive understanding of sero-prevalence and genetic differentiation of clinical and environmental pandemic isolates collected from around the world. Although, further studies are needed to delineate the specific mechanisms by which the pandemic strains evolve and spread, the findings in this study are helpful when seeking countermeasures to reduce the spread of V. parahaemolyticus in endemic areas.

Molecular and Conventional Analysis of Acute Diarrheal Isolates Identifies Epidemiological Trends, Antibiotic Resistance and Virulence Profiles of Common Enteropathogens in Shanghai

“…This data set only marks the beginning of longitudinal studies that will help us to dissect trends pathogens’ genetic microevolution overtime. While, ST3 presented the most dominant ST in V. parahaemolyticus , consistent with previous study in Asian countries ( Han et al, 2016 ), it strikingly differs from the predominant types in Maryland, United: ST631 and ST36 ( Haendiges et al, 2015 ) not found in our study. This is not surprising since the origins of V. parahaemolyticus at both sites are linked to Pacific and Atlantic Ocean, respectively, and involve different continents.…”

Prevalence and genetic diversity of human diarrheagenic Escherichia coli isolates by multilocus sequence typing

“…STs were assigned to clonal complexes (CCs) using eBURST v3 (Imperial College, London, UK), as described previously (Han et al, 2016). A CC was defined conservatively as a cluster of STs with primary founders positioned centrally in an eBURST diagram in which all STs are linked as single-locus variants (SLVs, two STs differing from each other at a single locus) to at least one other ST. For each CC, eBURST identifies the ST that is most likely to represent the founding genotype (the primary founder).…”

Simultaneous Identification of Clinically Common Vibrio parahaemolyticus Serotypes Using Probe Melting Curve Analysis

“…Therefore, the current assay presents a simple and pragmatic scheme for the rapid and accurate identification of V. parahaemolyticus serotypes, which is especially suited for real-time applications such as outbreak situations involving large number of samples be processed quickly in a short period of time. In developing this assay, we chose 11 V. parahaemolyticus serotypes that represented 90% of all serotypes isolated from human infections over a 10-year period (2007–2017) in Shenzhen, China; many of which are also commonly reported among infections domestically (Han et al, 2017) and worldwide (Velazquez-Roman et al, 2014; Han et al, 2016). Given its clinical relevance, the current assay could serve as an invaluable tool for clinical and public health laboratories.…”

“…In 1996, the emergence of a more virulent serotype O3:K6 was subsequently being recognized as a pandemic clone owing to its rapid dissemination and the cause of numerous gastroenteritis outbreaks globally (Nair et al, 2007). To date, the pandemic clone and its serovariants are known to represent 49 serotypes, which are widely distributed among 22 countries in Asia, Europe, America and Africa (Han et al, 2016). In China, up to 27 pandemic serovariants have been found amongst clinical samples, in which O3:K6, O4:K68, and O1:KUT predominated (Han et al, 2017).…”