Genomic characterization of an Acinetobacter baumannii ST25/International Clone 7 isolate carrying a resistance-associated plasmid from wild-caught oysters in the Southeastern USA.

Oysters are filter feeders that bioaccumulate microorganisms and other contaminants from water. Therefore, screening oysters facilitates monitoring of emerging antimicrobial-resistant pathogens in these habitats. Here, we report an in-depth genomic characterization of an antibiotic-resistant Acinetobacter baumannii that was isolated from a wild-caught oyster. Multilocus Sequence Typing (MLST) analyses assigned the strain to the ST25IP (Pasteur Scheme Sequence Type), which belongs to a lineage associated with antibiotic-resistance and epidemics. The strain was found to be antibiotic-resistant and carried multiple antibiotic resistance genes. Notably, four antibiotic resistance genes were located on a mobilizable plasmid that shared >99% sequence identity with plasmids reported internationally (Lebanon, Germany, Mexico, and Taiwan). Furthermore, using in-silico analyses, the isolate was predicted to be a potential human pathogen that harbored multiple virulence-associated genes. To our knowledge, this is the first report of an antibiotic-resistant A. baumannii (ST25IP) in oysters in the USA.