At the 2018 Allen D. Leman Swine Conference, discussion continued about new directions in antibiotic use and resistance.

Dr. Noelle Noyes of the University of Minnesota noted that antimicrobial resistance (AMR) is a "complex topic" that takes a lot of people to work on it. She said there are layers of complexity in AMR at both the systems level and the microbe level.

Noyes explained a recent study in beef cattle in which cattle entering a feedlot were given an antibiotic as metaphylaxis and their resistance patterns were compared to those not given metaphylaxis. There was no differences found in the resistome (pattern of resistance genes) between the treatment and control groups; however, there large resistome changes were noted in both group with the passage of time -- for some organisms, as little as 48 hours.

"Management practices may influence antimicrobial resistance," she said, and the context is important. "It is not just about antimicrobial use."