From vanA Enterococcus hirae to vanA Enterococcus faecium: a study of supplementation with avoparcin and tylosin in young chickens.

  1. Robredo, B. 1
  2. Singh, K.V. 22
  3. Baquero, F. 3
  4. Murray, B.E. 222
  5. Torres, C. 1
  1. 1 Universidad de La Rioja
    info

    Universidad de La Rioja

    Logroño, España

    ROR https://ror.org/0553yr311

  2. 2 University of Texas Health Science Center at Houston
    info

    University of Texas Health Science Center at Houston

    Houston, Estados Unidos

    ROR https://ror.org/03gds6c39

  3. 3 Hospital Ramón y Cajal
    info

    Hospital Ramón y Cajal

    Madrid, España

    ROR https://ror.org/050eq1942

Revista:
Antimicrobial Agents and Chemotherapy

ISSN: 0066-4804

Año de publicación: 1999

Volumen: 43

Número: 5

Páginas: 1137-1143

Tipo: Artículo

Otras publicaciones en: Antimicrobial Agents and Chemotherapy

Resumen

Fifteen newborn chickens were isolated in separate cages after 1 month of living together, divided into three groups, and challenged for 5 weeks with seed food which either was supplemented with avoparcin (10 mg/kg of animal food) or tylosin (40 mg/kg) or was nonsupplemented. At 9 weeks of age and after the 5-week challenge, all chickens received nonsupplemented feed for 4 additional weeks. At 4, 9, and 13 weeks of life, feces were collected and inoculated on M-Enterococcus agar plates with and without vancomycin (4 μg/ml), vanA-containing Enterococcus hirae was isolated from 11 of 15 chickens before antibiotic challenge, without detection of vancomycin- resistant Enterococcus faecium. At 9 weeks of age and after the 5-week avoparcin challenge, vanA E. hirae strains were no longer detected, but five of five chickens now had vanA E. faecium. At a lower frequency, vanA E. faecium had also displaced vanA E. hirae in both the tylosin group (one of four chickens) and the control group (two of five chickens). One month after avoparcin discontinuation, the number of chickens colonized with vanA E. faecium decreased from five to one. All vanA-containing E. hirae strains detected in the first month of life and most of the vanA-containing E. faecium strains detected in the second month of life showed identical ApaI and SmaI restriction patterns, respectively, when analyzed by pulsed-field gel electrophoresis. All vanA E. hirae isolates transferred glycopeptide and macrolide resistance to Enterococcus faecalis JH2-2 in vitro; the level of glycopeptide resistance was higher in the transconjugants than in the donor E. hirae strains. These data suggest that E. hirae may be a significant source of vanA determinants with the potential of transfer to other enterococcal species from humans or animals.