Quantification and Antimicrobial Resistance of Vibrio parahaemolyticus in Retail Seafood in Hanoi, Vietnam

Vibrio parahaemolyticus is a major cause of foodborne diseases and a significant threat to human health worldwide. Most of the infections caused by V. parahaemolyticus are usually associated with the consumption of raw or undercooked seafood. This study was conducted to determine the prevalence, quantitative load, and antimicrobial resistance of V. parahaemolyticus in retail seafood in Hanoi, Vietnam. A total of 120 seafood samples consisting of marine fish (n = 30), oysters (n = 30), shrimp (n = 30), and squid (n = 30) were purchased from different traditional markets in Hanoi between May and October 2020. Isolation of V. parahaemolyticus was based on ISO/TS 21872-1:2017, and the most-probable-number (MPN) method was used for quantification. The disk diffusion method was applied for antimicrobial susceptibility testing. Overall, V. parahaemolyticus was detected in 58.33% of the samples. V. parahaemolyticus was most commonly isolated in shrimp samples, with a prevalence of 86.67%, followed by fish (53.33%), squid (53.33%), and oysters (40%). One V. parahaemolyticus isolate from an oyster carrying the trh gene was detected. Of the positive samples, 27.14% contained V. parahaemolyticus counts of less than 2 log MPN/g, whereas 44.29% ranged from 2 to 4 log MPN/g and 28.57% contained more than 4 log MPN/g. Regarding antimicrobial resistance, 85.71% of V. parahaemolyticus isolates were resistant to at least one antibiotic tested. The highest rate of resistance was observed against ampicillin (81.43%), followed by cefotaxime (11.43%), ceftazidime (11.43%), trimethoprim-sulfamethoxazole (8.57%), and tetracycline (2.86%). The results demonstrate the high prevalence and quantitative load and the antimicrobial resistance of V. parahaemolyticus isolated from seafood sold in the study area.