385 Unraveling the gut-liver axis in Bovine liver abscesses: Isolation and characterization of Bacteroides from hepatic lesions.

Abstract Liver abscesses (LAs) in cattle reduce animal performance, increasing the environmental footprint of beef production and causing significant economic losses. These infections result from a translocation of opportunistic pathogens from the gastrointestinal (GI) tract into the blood stream where they can colonize the liver. The primary etiological agent of LAs is Fusobacterium necrophorum; however, recent research has found Bacteroides to be the second most prevalent bacterial group in up to 50% of LAs. Despite their beneficial role in the gut of ruminants, Bacteroides can cause severe infections when they breach the GI tract, leading to bacteremia, and the formation of abscesses in a variety of tissues. We have employed a combination of metagenomic and culture-based methods to isolate and identify the Bacteroides that are associated with liver abscesses in cattle. Two species of Bacteroides were isolated from the purulent material of liver abscesses, and whole genome sequencing conclusively identified these isolates as Bacteroides pyogenes, and a previously unknown species of Bacteroides. This analysis revealed putative virulence genes and identified distinct differences between LA-Bacteroides and most Bacteroides typically found in the GI-tract. In vivo assays have revealed insight into metabolic properties of these microbes. This data provides a critical foundation for expanding our knowledge of the potential role Bacteroides play in this process, and could contribute to the identification of novel targets for developing treatments to prevent this important production limiting disease.