Whole-genome insights into antibiotic resistance in Vibrio strains isolated from shrimp farms in Mexico

Despite notable advances in shrimp aquaculture over recent decades, infectious diseases remain a major limiting factor for further intensification. Among these, vibriosis has caused substantial economic losses worldwide. This study, therefore, aimed to identify and characterize virulence- and antibiotic resistance-associated genes in Vibrio species isolated from Mexican shrimp farms affected by disease outbreaks. Six Vibrio strains were isolated and identified through whole-genome sequencing. One strain was identified as Vibrio parahaemolyticus, which carries several antibiotic resistance genes on its chromosome and harbors a plasmid containing the pirA and pirB toxin genes responsible for acute hepatopancreatic necrosis disease (AHPND). The remaining five strains were identified as Vibrio diabolicus, which also carry several antibiotic resistance genes but lack the pirA- and pirB toxin genes. Moreover, multilocus sequence typing (MLST) analysis revealed that the V. parahaemolyticus strain identified in this study is genetically more closely related to strains previously isolated in China. In contrast, the V. diabolicus strains show greater similarity to a strain from Colombia, although genetic differences among them remain evident. Taken together, these findings highlight the complexity of genetic relationships among these isolates and suggest possible routes of global dissemination.