Supplementing animal feed with antimicrobial agents to enhance growth has been common practice for more than 30 years and is estimated to constitute more than half the total antimicrobial use worldwide.  The potential public health consequences of this use have been debated; however, until recently, clear evidence of a health risk was not available.  Accumulating evidence now indicates that the use of the glycopeptide avoparcin as a growth promoter has created in food animals a major reservoir of Enterococcus faecium, which contains the high level glycopeptide resistance determinant vanA, located on the Tn1546 transposon.  Furthermore, glycopeptide-resistant strains, as well as resistance determinants, can be transmitted from animals to humans.

This links to an article in the Center for Disease Control's "Emerging" Infectious Diseases journal.  Emerging Infectious Diseases represents the scientific communications component of CDC's efforts against the threat of emerging infections.  However, even as it addresses CDC's interest in the elusive, continuous, evolving, and global nature of these infections, the journal relies on a broad international authorship base and is rigorously peer-reviewed by independent reviewers from all over the world.