Animal and Farm Influences on the Dynamics of Antibiotic Resistance in Faecal Escherichia Coli in Young Dairy Calves

Prev Vet Med. 2005 Jun 10;69(1-2):25-38. doi: 10.1016/j.prevetmed.2005.01.013. Epub 2005 Feb 26.


It is believed that the intensive use of antibiotics in the management of disease in pre-weaned calves contributes to high levels of antibiotic resistance in commensal and pathogenic bacteria. We described the temporal dynamics of antibiotic-susceptibility patterns seen in bovine enteric Escherichia coli in pre-weaned calves on dairy farms and dedicated calf-rearing facilities. Cohorts of 30 calves at each of six farms were sampled at 2-week intervals during the pre-weaning period. Faecal E. coli isolates were analyzed for antibiotic susceptibility to 12 antibiotics with the disk-diffusion method and grouped using cluster analysis of inhibition-zone patterns. The influences of calf age, farm-type, and individual-calf antibiotic therapy on the clusterings were assessed using stratified analyses and cumulative multinomial logistic regression using generalized estimating equation with antibiotic-resistance cluster as an ordinal-dependent variable. The model controlled for farm and cohort by a nested design and included a repeated measure on calf at each sampling occasion. E. coli from calves 2 weeks of age were more likely to be increasingly multiply resistant than E. coli from day-old calves (OR = 53.6), as were 4- and 6-week-old calves (OR = 29.8 and 16.4, respectively). E. coli from calves on dedicated calf-rearing facilities were more likely to be increasingly multiply resistant than E. coli from dairy-reared calves (OR = 2.4). E. coli from calves treated with antibiotics within 5 days prior to sampling were also more likely to be increasingly multiply resistant than E. coli from calves not exposed to individual antibiotic therapy (OR = 2.0).

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animal Husbandry
  • Animals
  • Animals, Newborn
  • Animals, Suckling
  • Anti-Bacterial Agents / pharmacology*
  • Anti-Bacterial Agents / therapeutic use
  • California / epidemiology
  • Cattle
  • Cattle Diseases / drug therapy*
  • Cattle Diseases / epidemiology
  • Cattle Diseases / microbiology
  • Cohort Studies
  • Dairying
  • Drug Resistance, Bacterial*
  • Escherichia coli / drug effects*
  • Escherichia coli Infections / drug therapy
  • Escherichia coli Infections / veterinary*
  • Feces / microbiology
  • Female
  • Microbial Sensitivity Tests / veterinary
  • Prospective Studies


  • Anti-Bacterial Agents