Diversity of tet(L)-bearing plasmids found in Eastern Canadian Staphylococcus hyicus isolates from swine.

Staphylococcus hyicus is the etiological agent of exudative epidermitis (EE) in suckling and weaned piglets, which is an endemic disease of concern for animal health and welfare on swine farms. Staphylococcus hyicus is not widely studied, and there is no recent scientific literature on Canadian strains. In a preliminary study, we presented an Eastern Canadian S. hyicus strain isolated from an EE case and bearing a plasmidic tet(L) gene conferring resistance to tetracyclines, one of the most commonly used antibiotics in Canadian swine farms. The current study characterized the tet(L)-bearing plasmids present in S. hyicus isolates from pigs in Eastern Canadian to better understand the potential vectors for this gene dissemination. Eleven S. hyicus isolates harboring tet(L) as the only tetracycline resistance gene were sequenced using Oxford Nanopore Technology and analyzed. Eight different tet(L)-bearing plasmids were identified that share similarities with Staphylococcus aureus sequences available in the National Center for Biotechnology Information. Only one of the plasmids was present in more than one isolate and two isolates carried tet(L) on their chromosome. This suggests a high diversity of tet(L)-bearing plasmids in S. hyicus and the possible need to analyze swine farm samples over time to understand the dynamics of tet(L) in S. hyicus.