<OL> <LI> Determine the antimicrobial resistance patterns of Salmonella, E. coli, Enterococci and Campylobacter isolates obtained from finisher swine fed three different antibiotic feeding regimens <LI>Determine the molecular relatedness between isolates <LI>Characterize the resistance genes within these isolates.
Approach: 1) Antimicrobial resistance in Salmonella, E. coli, and Enteoccocci will be determined using a semi-automated broth microdilution sensititre system (TREK Diagnostics, Inc.) and custom designed antimicrobial plates as used in the NARMS program. The E-test will be used to determine resistance in Campylobacter. 2) PFGE, and sequencing will be used to determine the molecular relatedness between isolates. 3) Microarrays, hybirdization, sequencing, plasmid analysis, and PCR will be used to characterize the resistance genes.