Molecular epidemiological analysis of Vibrio parahaemolyticus in foodborne diseases in Liaoning province, 2023–2024

Introduction Vibrio parahaemolyticus (VP) is a major pathogen causing foodborne diseases, and Liaoning Province, a coastal region with high seafood consumption and production, faces a notable risk of VP-associated foodborne infections. Clarifying the molecular epidemiological characteristics of VP in this region is critical for targeted prevention and control of such diseases. This study aimed to investigate the molecular epidemiological features, virulence gene profiles, and antibiotic resistance gene distribution of VP isolated from foodborne disease cases in Liaoning Province during 2023-2024, providing precise data support for VP prevention and control. Methods Whole-genome sequencing (WGS) was performed on 261 clinical isolates of Vibrio parahaemolyticus collected in Liaoning province from 2023 to 2024. Multilocus sequence typing (MLST), virulence gene identification, and antibiotic resistance gene detection were conducted and combined with epidemiological surveillance data to analyze the association between genetic and epidemiological characteristics. Results A total of 10,413 foodborne disease cases were monitored during 2023–2024, with 261 isolates of Vibrio parahaemolyticus identifed (detection rate: 2.51%). The positive rate in 2024 (3.59%) was significantly higher than that in 2023 (1.27%, P < 0.05). Vibrio parahaemolyticus infections showed obvious seasonal characteristics, with the majority of cases occurring in July–September, with a peak in August, and consistent seasonal epidemic dynamics were observed between 2023 and 2024. Aquatic animals and their products (including fish, shellfish, crustaceans, and their fresh/processed products) were the most common exposure food category (52.11%). Restaurants (37.55%) and homes (34.87%) were the main eating venues for infected cases. Among antibiotic resistance genes, tet (34) and bla CARB-22 had the highest carriage rates (100% and 94.64%, respectively). Among the 71 detected virulence genes, 61 were core virulence genes shared by all isolates, and flg B had the highest deletion rate (95.79%). MLST analysis identified 11 sequence type based on typing results, with ST3 as the dominant epidemic strain (94.25%). Conclusion Vibrio parahaemolyticus infections in Liaoning province have clear and stable seasonal characteristics during 2023–2024, with aquatic animals and their products as the main exposure source. ST3 is the dominant epidemic strain and is associated with the carriage of tet (34), bla CARB-22, and a variety of virulence genes based on genomic detection. The resistance gene profile of Vibrio parahaemolyticus isolates shows regional heterogeneity in Liaoning Province. Strengthening seafood safety supervision and continuous monitoring of the ST3 strain, as well as tracking of multidrug-resistant isolates, are of great significance for the scientific prevention and control of Vibrio parahaemolyticus foodborne diseases.