Diversity and distribution of commensal fecal Escherichia coli bacteria in beef cattle administered selected subtherapeutic antimicrobials in a feedlot setting.

ABSTRACT: Escherichia coli strains isolated from fecal samples were screened to examine changes in phenotypic and genotypic characteristics including antimicrobial susceptibility, clonal type, and carriage of resistance determinants. The goal of this 197-day study was to investigate the influence of administration of chlortetracycline alone (T) or in combination with sulfamethazine (TS) on the development of resistance, dissemination of defined strain types, and prevalence of resistance determinants in feedlot cattle. Inherent tetracycline resistance was detected in cattle with no prior antimicrobial exposure. Antimicrobial administration was not found to be essential for the maintenance of inherently ampicillin-resistant and tetracycline-resistant (Tet(r)) E. coli in control animals; however, highe

SUBMITTER: Sharma R 

PROVIDER: S-EPMC2570304 | biostudies-literature | 2008 Oct

REPOSITORIES: biostudies-literature