Marine Plastics from Norwegian West Coast Carry Potentially Virulent Fish Pathogens and Opportunistic Human Pathogens Harboring New Variants of Antibiotic Resistance Genes

To our best knowledge this is the first study characterizing fish pathogens isolated from marine plastics from the West coast of Norway for their potential for pathogenicity using whole genome sequencing. Marine plastic polymers identified as polyethylene, polyethylene/ethylene vinyl acetate copolymer and polypropylene, yielded a total of 37 bacterial isolates dominated byPseudomonasspp. (70%). Six isolates representing either fish pathogens or opportunistic human pathogens were selected for whole genome sequencing (WGS). These included four isolates belonging toAeromonasspp., oneAcinetobacter beijerinckiiisolate and oneMorganella morganiiisolate. ThreeAeromonas salmonicidaisolates were potentially virulent and carried virulence factors involved in attachment, type II and type VI secretion systems as well as toxins such asaerA/act, ahh1, ast, hlyA, rtxAandtoxA. A. salmonicidaandAcinetobacter beijerinckiicarried new variants of antibiotic resistance genes (ARGs) such as beta-lactamases and chloramphenicol acetyltransferase (catB), whereasMorganella morganiicarried several clinically relevant ARGs. Our study shows that marine plastics carry not only potentially virulent fish pathogens but also multidrug resistant opportunistic human pathogens likeM. morganiiand may serve as vectors for transport of these pathogens in the marine environment.