The effect of growth-promoting antibiotics on the faecal enterococci of healthy young chickens

J Appl Bacteriol. 1988 Jan;64(1):57-64. doi: 10.1111/j.1365-2672.1988.tb02429.x.


Small groups of chickens were given feed containing either avoparcin, nitrovin, virginiamycin or zinc bacitracin from the day of their purchase as day-olds. Differences between the birds receiving growth promoters and the untreated controls were observed during the last third of the 23 d survey period. The enterococcal population of the 'dosed' birds contained a greater proportion of Enterococcus faecium than did that of the control birds while the converse was true for Ent. gallinarum. This apparent selection of Ent. faecium by the growth-promoting antibiotics had an influence on the incidence of resistance to therapeutic antibiotics among the enterococcal population as a whole. This was because this species was generally more resistant than Ent. gallinarum to cephalothin, the MLS antibiotics (erythromycin, lincomycin and tylosin) and tetracycline.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animal Feed
  • Animals
  • Anti-Bacterial Agents* / administration & dosage*
  • Anti-Bacterial Agents* / pharmacology
  • Bacitracin / administration & dosage
  • Bacitracin / pharmacology
  • Chickens / microbiology*
  • Drug Resistance, Microbial
  • Enterococcus faecalis / drug effects
  • Enterococcus faecalis / isolation & purification
  • Feces / microbiology*
  • Glycopeptides / administration & dosage
  • Glycopeptides / pharmacology
  • Nitrovin / administration & dosage
  • Nitrovin / pharmacology
  • Streptococcus / drug effects
  • Streptococcus / isolation & purification*
  • Virginiamycin / administration & dosage
  • Virginiamycin / pharmacology


  • Anti-Bacterial Agents
  • Glycopeptides
  • Virginiamycin
  • Bacitracin
  • Nitrovin
  • avoparcin