Prevalence, genomic characteristics, and antimicrobial resistance of Vibrio parahaemolyticus from various aquatic products in Jiangsu Province, 2019—2021

ObjectiveTo investigate the distribution characteristics of Vibrio parahaemolyticus from different aquatic product sources in Jiangsu Province from 2019 to 2021， and to analyze the differences in genomic characteristics and antimicrobial resistance.MethodsThis study analyzed the temporal and source-specific distribution of Vibrio parahaemolyticus that was detected from 838 aquatic product samples （collected between 2019 and 2021） using the method outlined in GB 4789.7—2013. Whole-genome sequencing （WGS） and antimicrobial susceptibility testing were conducted on 55 successfully revived Vibrio parahaemolyticus strains. Bioinformatics analyses were employed for phylogenetic construction， virulence and resistance gene screening， and serotype predicting， from which serotypes were validated using traditional serum agglutination method.ResultsA total of 92 Vibrio parahaemolyticus strains were detected， with a detection rate of 10.98%， showing no statistically significant difference among different food sources （χ²=0.44， P=0.801）. Among the 55 sequenced strains， 34 strains were classified into 33 sequence types （STs）， while STs of 21 strains were unknown. The predominant serotype in seafood isolates was O5：K17 （18.52%）， while O2：K22 （26.32%） was predominant in freshwater product isolates. Derivative serotypes O5：K17 and O1：K25 of the pandemic serotype O3：K6 were detected in both seafood and freshwater product isolates. None of the strains carried the tdh gene， while only two seafood isolates harbored trh， along with hlyB and hlyC genes. All strains were resistant to cefazolin. Quinolone resistance genes qnrC and qnrS5 were detected exclusively in one freshwater product isolate.ConclusionVibrio parahaemolyticus in Jiangsu province demonstrated diverse distributions in both STs and serotypes. The primary risk associated with seafood lies in the combinations of predominant pandemic lineages and the presence of specific virulence gene， where freshwater products serve as a critical reservoir for the emergence and transmission of antimicrobial resistance genes with high risks. Pickled aquatic products are also potential sources of food safety risk， which require strengthened surveillance.