#18-180

Progress

Date Full Report Received

Date Abstract Report Received

Investigation

Institution:
Primary Investigator:
Co-Investigators: Scott A. Dee, Noelle Noyes, Roy Edler, Joel Nerem, Peter Davies

Funded By

Public concern appears to be growing regarding the risk of a foodborne route of antimicrobial resistance (AMR) from food animals to humans and persistence of AMR in the environment. For two bacteria commonly used to monitor AMR in animals and humans (Enterococcus spp. and Escherichia coli) we compared AMR patterns from weaning to market in bacteria from groups of pigs given different antibiotic therapies. Additionally, we gained a better understanding of the dynamics of AMR in the swine environment following industry standard sanitation practices.
This experimental challenge study was conducted at a newly constructed wean to finish research barn with no pigs previously housed in it. A PRRSV challenge model was used to mimic real life scenarios requiring antibiotic use in the field. There were three treatment groups – 1) PRRSV negative / Minimal antibiotic use, 2) PRRSV challenged / Moderate antibiotic use, and 3) PRRSV challenged / Intensive antibiotic use.
Initial testing demonstrated that pigs carried antibiotic resistant bacteria shortly after weaning despite piglets and their dams not receiving antibiotics during lactation. Regardless of widely differing intensities of exposure to antibiotics during the nursery phase, we found minimal and inconsistent differences between treatment groups that were mostly not reconcilable with the antibiotic treatments applied. The results suggest that antimicrobial resistance patterns in response to antibiotic exposure may be influenced as much by historic exposures in herds, or by other factors, than short-term antibiotic exposures.

Key Findings:
• Initial testing demonstrated that pigs carried antibiotic resistant bacteria shortly after weaning despite piglets and their dams not receiving antibiotics during lactation.
• Regardless of widely differing intensities of exposure to antibiotics during the nursery phase, we found minimal and inconsistent differences between treatment groups that were mostly not reconcilable with the antibiotic treatments applied.
• The results suggest that antimicrobial resistance patterns in response to antibiotic exposure may be influenced as much by historic exposures in herds, or by other factors, than short-term antibiotic exposures.