Submitted to: University of Georgia Research Report
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2002
Publication Date: 3/21/2002
Citation: Kim, L.M., Cray, P.J., Jones, R.D. 2002. Antimicrobial resistance in e. coli from piglets fed diets with and without antimicrobials [Abstract]. University of Georgia Research Report. P. 230-237. Interpretive Summary:
Technical Abstract: The objective of this study was to evaluate the antimicrobial susceptibilities of fecal E. coli populations from growing piglets fed diets with and without feed-based subtherapeutic anitimicrobials (FSAs). Diets with and without subtherapeutic apramycin (Phase 1), carbadox (Phase 2 and 3), and tetracycline (Phase 4) were used. Fecal samples were cultured regularly from sows and all piglets, and antimicrobial susceptibility of E. coli to tetracycline, apramycin, and gentamicin was tested. Performance measurements were also included. In total 27,049 isolates were analyzed (trial 1=7,557, trail 2=8,772, trail 3=10,720). Overall, resistance to tetracycline was relatively high and gentamicin resistance was low regardless of sample, group, or trail. For piglets in trails 1 and 3, resistance to apramycin (Table 1) was higher in pigs fed subtherapeutic apramycin (Phase 1), and then declined during feeding of carbadox (Phases 2 and 3). In trail 2, increased resistance to apramycin did not occur in pigs fed subtherapeutic antimicrobials during Phases 1 through 4. Differences in performance were sporadic between trails except during Phase 4. For this phase in all trails, average daily gains and daily feed intakes were higher for the piglets fed FDAs; however, the differences were not consistently reflected in feed effciency or adjusted d to 250 lb. While the initial results of this study suggest that antimicrobial resistance will increase with FSA use, there are indicators that production use of FSAs can have complex effects on the antimicrobial resistance patterns of enteric bacteria. Further research is warranted to fully understand the interaction between FSAs and the occurrence and persistence of antimicrobial resistance.