Genome Sequences of Four Vibrio parahaemolyticus Strains Isolated from the English Channel and the River Thames

The increased prevalence of Vibrio species and the first reporting of Vibrio jasicida and Vibrio rotiferianus at UK shellfish sites

Warming sea-surface temperature has led to an increase in the prevalence of Vibrio species in marine environments. This can be observed particularly in temperate regions where conditions for their growth has become more favourable. The increased prevalence of pathogenic Vibrio species has resulted in a worldwide surge of Vibriosis infections in human and aquatic animals. This study uses sea-surface temperature data around the English and Welsh coastlines to identify locations where conditions for the presence and growth of Vibrio species is favourable. Shellfish samples collected from three locations that were experiencing an increase in sea-surface temperature were found to be positive for the presence of Vibrio species. We identified important aquaculture pathogens Vibrio rotiferianus and Vibrio jasicida from these sites that have not been reported in UK waters. We also isolated human pathogenic Vibrio species including V. parahaemolyticus from these sites. This paper reports the first isolation of V. rotiferianus and V. jasicida from UK shellfish and highlights a growing diversity of Vibrio species inhabiting British waters.

Prevalence and Population Analysis of Vibrio parahaemolyticus Isolated from Freshwater Fish in Zhejiang Province, China

Objectives: The previous researches revealed that Vibrio parahaemolyticus has been detected in freshwater fish samples. However, the molecular characteristics of V. parahaemolyticus isolated from freshwater fish, including pathogenic and pandemic strains, are still unknown. This study aims to characterize and identify molecular properties of the bacterium. In addition, it identifies the source of V. parahaemolyticus from freshwater fish samples in Zhejiang Province, China. Methods: Four hundred and twenty-one freshwater fish samples (from fishing farms, retail markets, and restaurants) and 212 seafood samples (from retail markets) were collected in 10 cities of Zhejiang Province. V. parahaemolyticus strains were isolated from these samples and comparatively analyzed by multilocus sequence typing, serotyping, antimicrobial susceptibility test, and polymerase chain reaction, targeting common toxin genes (tdh, trh) and markers for pandemic strains (orf8, toxRS/new). Results: Sixty-eight V. parahaemolyticus strains were isolated from the 421 freshwater fish samples, and 89 V. parahaemolyticus isolates were identified out of 212 seafood samples. The detection rate of V. parahaemolyticus was significantly different (p < 0.05) between the fishing farms, the retail markets, and the restaurants. The isolates from freshwater fish samples were divided into eight O serotypes with three O3:K6 isolates, which contain three pandemic complexes (tdh⁺, orf8⁺, toxRS/new⁺). A total of 53 different sequence types (STs) were identified among the 68 isolates, including 28 novel STs. Antimicrobial susceptibility results indicated that 76.5% of the strains were resistant to ampicillin. A third (3/9) of the isolates from fishing farm sources shared the same STs with their counterparts from retail markets. Compared with the isolates from the seafood samples collected in the same sampling sites, 13.2% (9/68) freshwater fish isolates overlapped with seafood isolates. Conclusions: Our study showed that V. parahaemolyticus population in freshwater fish is genetically diverse. The V. parahaemolyticus contaminates might have come from both fishing farm sources and cross-contamination from seafood in the closed area at the markets. Freshwater fish may work as a reservoir of pathogenic and pandemic V. parahaemolyticus isolates, indicating potential public health and food safety risks associated with the consumption of freshwater fish.