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

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.

Prevalence, Virulence Characterization, AMR Pattern and Genetic Relatedness of Vibrio parahaemolyticus Isolates From Retail Seafood of Kerala, India

“…The results of our study revealed that there is no consensus among the results of three methods employed for the detection of pandemic isolates. Similar observations of variance in results among the methods used for detection of pandemic strains were made by Li et al (2016) where the prevalence of GS-PCR, PGS PCR, Orf8, and HUα positive isolates were reported to be 81.9, 38.9, 16.9, and 18.9%, respectively. Another study conducted in the eastern coastal region of India reported PGS-PCR and GS-PCR positive isolates to be, respectively, 6.5% and 2.4% of pathogenic isolates (Parthasarathy et al, 2016).…”

Genetic and virulence characterisation of Vibrio parahaemolyticus isolated from Indian coast

“…Another striking observation is the appearance of tdh − trh + isolates carrying the toxRS/ new + pandemic marker. Pandemic strains of V. parahaemolyticus are mostly associated with the tdh gene with few reports of GS-positive trh-containing isolates from clinical cases [23,37,38]. Data pertaining to the pandemic status of environmental trh-positive V. parahaemolyticus is lacking.…”

Serology, virulence and molecular characteristics of Vibrio parahaemolyticus isolated from seafood in Zhejiang province

“…PCR assays to amplify the pandemic markers were performed using specific primers previously reported to detect toxRS/new [ 11 ] and orf8 sequence [ 18 ]. The PCR cycling parameters for these assays were as follows: for the toxRS/new gene, initial denaturation at 94°C for 3 min, followed by 25 cycles of 30s at 94°C, 30s at 45°C, and 1 min at 72°C, with a final extension of 5 min at 72°C, and for the orf8 gene, denaturation at 96°C for 5 min, followed by 25 cycles of 1 min at 94°C, 1 min at 53°C, and 1 min at 72°C, with a final extension of 7 min at 72°C.…”