Abstract:
Objective To obtain the sequence distribution characteristics of Vibrio parahaemolyticus strains isolated from four outbreaks in Fuzhou, Fujian province, and analyze genetic correlations among different strains.
Methods The 19 strains of V. parahaemolyticus were sequenced with whole genome sequencing (WGS). Genome assembly and gene prediction for sequenced strains were performed using corresponding bioinformatics software. Multilocus sequence typing, antibiotic resistance genes and virulence genes of the V. parahaemolyticus strains were discovered using relevant databases. The phylogenetic tree was constructed by the maximum likelihood method.
Results The 19 V. parahaemolyticus strains were classified into four sequence types according to seven housekeeping genes, ST3 was the predominant STs and there was 1 strain belonged to an unknown ST. All the strains contained β -lactam and tetracycline antibiotic resistance genes, and carried important virulence genes causing pathogenicity of host cells. Two quinolone resistance genes and 1 trh+ virulence gene were detected only in F265 strain. The phylogenetic tree evolution analysis showed that the strains isolated in the outbreaks could be divided into three evolutionary clades, with strains E2019, E2020-1, and E2020-2 mainly in lineage B evolutionary branch and strains E2018 all in lineage C evolutionary branch.
Conclusion The V. parahaemolyticus causing the four outbreaks were predominated by ST3 clonal complex accompanied by other STs. The strains isolated from the same outbreak showed genetic diversity. The sequencing data provided technical support for source tracing of the outbreaks.
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