Impact of treatment strategies on cephalosporin and tetracycline resistance gene quantities in the bovine fecal metagenome. Academic Article uri icon


  • The study objective was to determine the effects of two treatment regimens on quantities of ceftiofur and tetracycline resistance genes in feedlot cattle. The two regimens were ceftiofur crystalline-free acid (CCFA) administered to either one or all steers within a pen and subsequent feeding/not feeding of therapeutic doses of chlortetracycline. A 26-day randomized controlled field trial was conducted on 176 steers. Real-time PCR was used to quantify bla(CMY-2), bla(CTX-M), tet(A), tet(B), and 16S rRNA gene copies/gram of feces from community DNA. A significant increase in ceftiofur resistance and a decrease in tetracycline resistance elements were observed among the treatment groups in which all steers received CCFA treatment, expressed as gene copies/gram of feces. Subsequent chlortetracycline administration led to rapid expansion of both ceftiofur and tetracycline resistance gene copies/gram of feces. Our data suggest that chlortetracycline is contraindicated when attempting to avoid expansion of resistance to critically important third-generation cephalosporins.

published proceedings

  • Sci Rep

altmetric score

  • 1

author list (cited authors)

  • Kanwar, N., Scott, H. M., Norby, B. o., Loneragan, G. H., Vinasco, J., Cottell, J. L., ... Boerlin, P.

citation count

  • 35

complete list of authors

  • Kanwar, Neena||Scott, H Morgan||Norby, Bo||Loneragan, Guy H||Vinasco, Javier||Cottell, Jennifer L||Chalmers, Gabhan||Chengappa, Muckatira M||Bai, Jianfa||Boerlin, Patrick

publication date

  • January 2014