Vancomycin-Resistant Enterococci in Turkeys and Farmers

To the Editor: In enterococci vancomycin resistance of the VanA phenotype is usually due to the presence of seven genes organized in a cluster on a transposon (Tn1546).1,2 The recent emergence of vancomycin-resistant enterococci is believed to be due to the vertical clonal spread of resistant strains and the horizontal spread of the transposon itself among different strains of enterococci in a selective environment. Use of avoparcin — a glycopeptide, like vancomycin — as an antimicrobial growth promoter in animal feeds creates such a selective environment and causes the selection of vancomycin-resistant enterococci in the intestinal flora. . . .