Epidemiology of antimicrobial resistance in enterococci of animal origin

J Antimicrob Chemother. 2005 Jan;55(1):127-30. doi: 10.1093/jac/dkh508. Epub 2004 Dec 1.

Abstract

Objective: We evaluated the epidemiology of antimicrobial resistance in enterococci from animal farms and the potential relation of resistance to antimicrobial use.

Methods: Enterococci from faecal samples from 18 beef cattle, 18 dairy cattle, 18 swine, 13 chicken, and eight turkey farms were prospectively evaluated over a 6 year period from 1998 to 2003.

Results: We evaluated 1256 isolates of Enterococcus faecium and 656 isolates of Enterococcus faecalis. None was vancomycin resistant. Quinupristin/dalfopristin, gentamicin and ciprofloxacin resistance rates in E. faecium were 2%, 0% and 55% in beef cattle, 8%, 7% and 47% in dairy cattle, 21%, 1% and 47% in swine, 85%, 12% and 23% in chicken, and 52%, 13% and 24% in turkey isolates, respectively. For E. faecalis, gentamicin resistance rates were 0% in beef cattle, 24% in dairy cattle, 37% in swine, 32% in chicken, and 29% in turkey isolates, whereas 12%, 9%, 21%, 64% and none of isolates from beef, dairy, swine, chicken, and turkey farms, respectively, were resistant to ciprofloxacin. Quinupristin/dalfopristin resistance in E. faecium was more common on chicken and turkey farms using virginiamycin (P<0.0001 for both) compared with farms not using a streptogramin, gentamicin resistance was more common on dairy farms using gentamicin (P<0.0001) compared with farms not using this antibiotic, and ciprofloxacin resistance was more common on turkey and dairy farms using enrofloxacin compared with those with no enrofloxacin use (P=0.02 and P=0.04, respectively). For E. faecalis, gentamicin resistance was more frequently detected on dairy and swine farms using gentamicin (P<0.0001 and P=0.0052, respectively) and ciprofloxacin resistance was more common on beef farms using enrofloxacin (P<0.0001) compared with farms not using these antimicrobials. PFGE showed multiple strain types with some clones common between animals of the same animal species.

Conclusions: This study shows the presence of a significant reservoir of antibiotic-resistant enterococci among farm animals. Resistance was more common on farms using antimicrobial agents.

Publication types

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

MeSH terms

  • Agriculture
  • Animals
  • Animals, Domestic / microbiology*
  • Anti-Bacterial Agents / pharmacology*
  • Cattle
  • Cattle Diseases / epidemiology
  • Cattle Diseases / microbiology
  • Chickens / microbiology
  • Drug Resistance, Bacterial*
  • Enterococcus faecalis / drug effects*
  • Enterococcus faecalis / isolation & purification
  • Enterococcus faecium / drug effects*
  • Enterococcus faecium / isolation & purification
  • Feces / microbiology
  • Gram-Positive Bacterial Infections / epidemiology
  • Gram-Positive Bacterial Infections / microbiology
  • Gram-Positive Bacterial Infections / veterinary*
  • Microbial Sensitivity Tests
  • Midwestern United States
  • Poultry Diseases / epidemiology
  • Poultry Diseases / microbiology
  • Turkeys / microbiology

Substances

  • Anti-Bacterial Agents