Epidemiology of antimicrobial resistance in enterococci of animal origin.
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.
Hershberger
Ellie
E
Division of Infectious Disease, Department of Medicine, Wayne State University School of Medicine, William Beaumont Hospital, 3811 West 13 Mile Road, Royal Oak, MI 48073, USA.
Oprea
Simona F
SF
Donabedian
Susan M
SM
Perri
Mary
M
Bozigar
Pamela
P
Bartlett
Paul
P
Zervos
Marcus J
MJ
D000383:Agriculture; D000818:Animals; D000829:Animals, Domestic / Q000382:microbiology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000382:microbiology; D002645:Chickens / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000302:isolation & purification; D016984:Enterococcus faecium / Q000187:drug effects* / Q000302:isolation & purification; D005243:Feces / Q000382:microbiology; D016908:Gram-Positive Bacterial Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D008826:Microbial Sensitivity Tests; D015146:Midwestern United States; D011201:Poultry Diseases / Q000453:epidemiology / Q000382:microbiology; D014422:Turkeys / Q000382:microbiology
D000900:Anti-Bacterial Agents