2012 Annual Report 1a.Objectives (from AD-416): Determine the antimicrobial resistance of E. coli from cattle reared with various antibiotic usage regimens. Are there intervention strategies that can reverse antimicrobial resistance? 1b.Approach (from AD-416): 1) Will culture approximately 1000 cattle fecal samples for E. coli;. 2)E. coli will be tested for antibiotic sensitivities;. 3)Resistant bacteria will be genotypically characterized; and. 4)Antibiotic usage practices will be altered and cattle populations re-distributed to reduce antibiotic resistance. 3.Progress Report: This is a new project with the goal of developing technologies to preserve efficacies of existing antibiotics. Increased antimicrobial resistance has been observed in bacterial pathogens encountered in human and veterinary medicine. Project work in FY 2012 focused on identifying factors affecting the transmission of antimicrobial-sensitive and -resistant bacterial populations between different groups of feedlot cattle. The work established that sensitive bacterial populations were often times able to displace resistant bacterial populations; efforts to elucidate reasons for this preferential colonization are ongoing. Data from project research indicates that animal production practices such as the judicious use of antimicrobials, the segregation of sick and healthy animals, and the manipulation of beneficial gut bacteria can be used to improve animal health and reduce the acquisition and persistence of antimicrobial-resistant populations in feedlot cattle. This project expires in early FY 2013, but the work will be continued by the parent project in ongoing cooperation with the collaborator.