Multilocus sequence typing of antimicrobial-resistant zoonotic bacteria from shrimp aquaculture environments in...

Vibrio species, Escherichia coli and Salmonella are the major zoonotic pathogens associated with seafood-related illnesses and are found in shrimp aquaculture. Understanding their genetic diversity and the potential for antimicrobial resistance (AMR) spread is critical for safeguarding food safety and effective disease management. To date, there is limited information about the genetic diversity of zoonotic bacteria in Malaysian shrimp aquaculture. Hence, this research investigated the genetic profiles of four V. parahaemolyticus, three Escherichia coli and two Salmonella strains isolated from shrimp aquaculture environments in Selangor, Malaysia, using multilocus sequence typing (MLST). The results showed that two V. parahaemolyticus strains, KLA-W-VP (non-resistant) and SBM-W-VP (multidrug-resistant, MDR), were novel and assigned sequence types ST3747 and ST3748, respectively. Whereas, an MDR V. parahaemolyticus strain KSR-W-VP1 belonged to the existing ST1160. Similarly, novel MDR E. coli strains KLE-W-E and SBI-W-E2 (MAR index 0.5) were assigned ST2118 and ST2117, respectively, while the non-resistant strain KSP-U-E belonged to existing ST2085. The non-resistant Salmonella strains KLE-W-Sa and SBK-U-Sa (MAR index 0.2) were closely related to Salmonella enterica from animals in the United States. This study identified several new genetic types of zoonotic strains with diverse AMR characteristics linked to shrimp aquaculture environments. Most of the V. parahaemolyticus strains possess close genetic relationships with environmental sources from Asia, while the E. coli strains showed genetic similarity to animal sources from North America. The findings of this study indicate that shrimp aquaculture environments may serve as reservoirs for the dissemination of zoonotic bacteria and AMR across various geographical regions.