Antibiotic Use in Oyster Hatcheries Promotes Rapid Spread of a Highly Transferable and Modular Resistance Plasmid in Vibrio

Chloramphenicol treatment selected for resistant Vibrio isolates carrying the catA2 gene on a conjugative plasmid, pAQU-MAN. This plasmid, highly transferable and stable, spread rapidly across the hatchery and transferred efficiently to oyster- and human-pathogenic Vibrio as well as E. coli.
It was also inherited by oyster progeny, even without antibiotics, but disappeared in adult-associated microbial communities.

The findings highlight how antibiotic use in aquaculture can drive the emergence of mobile multidrug-resistant plasmids with ecological and public health implications.