Prevalence and genetic diversity of three food-borne pathogens in prepared aquatic dishes in Guangdong, China

Benefiting from advances in cold-chain logistics, China’s prepared aquatic dishes sector has emerged as a rapidly growing food industry. However, contamination risks persist due to transmission of Vibrio parahaemolyticus , Salmonella spp., and Listeria monocytogenes . Therefore, this study investigated the prevalence of these three foodborne pathogens in prepared aquatic dishes across Guangdong Province, China, while simultaneously characterizing their virulence genes, antibiotic resistance profiles, biofilm formation ability (BFA), and genetic diversity. Among 207 sampled, V. parahaemolyticus exhibited the highest contamination rate (22.70%), significantly exceeding Salmonella spp. (1.44%) and L. monocytogenes (0.97%). The thermostable direct hemolysin-related hemolysin gene ( trh ) was detected in 1.51% of V. parahaemolyticus isolates. Antimicrobial susceptibility testing revealed a high resistance rate to streptomycin (88.94%) and ampicillin (85.93%) in V. parahaemolyticus, whereas Salmonell a spp. displayed multidrug resistance. All L. monocytogenes isolates were resistant to ceftazidime. Notably, a subset of isolates demonstrated strong BFA. Multilocus sequence typing (MLST) analysis of 222 isolates identified 136 sequence types (STs), including 70 novel STs. These findings underscore significant consumer health risks posed by high pathogen contamination rates, multidrug resistance prevalence, and extensive genetic diversity, highlighting the imperative for enhanced microbial surveillance within this industry. • V. parahaemolyticus contaminates 22.7% of aquatic prepared dishes. • Aquatic prepared dishes harbor Salmonella , and L. monocytogenes contamination. • 1.51% of V. parahaemolyticus carry the trh gene. • Some isolates exhibit multidrug resistance and strong biofilm formation. • 136 sequence types (STs) were identified, including 70 novel types.