Submitted to: International Debate Conference for the Feed and Food Chain
Publication Type: Abstract Only
Publication Acceptance Date: January 31, 2005
Publication Date: January 31, 2005
Citation: Cray, P.J., Robens, J.F. 2005. THE US GOVERNMENT'S STRATEGY ON ANTIMICROBIAL GROWTH PROMOTERS. International Debate Conference for the Feed and Food Chain. January 31 - February 1, 2005. Noordwijk aan Zee, Netherlands. Technical Abstract: The development of antimicrobial resistance has become a global problem. Resistance emerged shortly after introduction of the penicillins and has since been observed for all antimicrobial drug classes. Although decreased bacterial susceptibility could adversely affect clinical outcome, it has been observed that susceptibility to antimicrobials is not shared equally among bacterial species, or even between different strains of the same bacterial species. Antimicrobial drugs are used throughout the world in animals, humans, and on plants. They are an important and critical component in treating disease in human (and animal) medicine. The extent to which antimicrobial resistance currently impacts human health is not known, but there is increasing global pressure to protect the effectiveness of antimicrobials by limiting antimicrobial use. Although the development of resistance has been largely attributed to overuse and abuse of antimicrobials in human medicine, agricultural uses have also contributed to the problem. While all uses of antimicrobial drugs are under review, significant attention has been focused on antimicrobial use in animals. Antimicrobials are used in animal production for treatment of disease, for prophylactic use in prevention of disease, and to enhance growth and performance. Low levels, well below therapeutic concentrations, are typically used for growth promotion; antimicrobials are typically placed in animal feeds and all animals within the production unit have access to this feed. Although the development of resistance varies between bacterial species, the rate and extent of the development of resistance among bacteria common to the animal production environment is unknown. However, resistance will develop among some bacterial species and strains, even at the low drug concentration. The extent to which the use of antimicrobials for growth promotion impacts human and animal health is widely debated. The correlation between use and resistance, particularly among zoonotic bacteria, has provided the impetus for some groups and individuals to propose limiting or banning antimicrobials from use, particularly as growth promotants. In Europe, bans based on the precautionary principle against subtherapeutic use of feed grade antimicrobials are already in place. In the U.S., no official ban is in place, although the issue evokes passionate debate. While the U.S. government has no official policy on growth promotant use, the Food and Drug Administration has developed a guidance for industry on antimicrobials. Guidance Document #152, Evaluating the Safety of Antimicrobial New Animal Drugs with Regard to Their Microbiological Effects on Bacteria of Human Health Concern, focuses on the drugs themselves, which includes antimicrobials used for growth promotion. GD#152 regulates the labeling and marketing of antimicrobials for use in animals and addresses both the pre-approval assessment of microbial safety and the re-evaluation of currently approved antimicrobials. The FDA has completed one risk assessment on Virginiamycin (an antimicrobial used for growth promotion in animals) and its impact on resistance to Synercid, which is used in human medicine. Evaluation of several other antimicrobials used for growth promotion is ongoing. The increased scrutiny and global pressure to develop strategies to expand the lifespan of antimicrobials is producing an immediate need for more scientific data. The U.S. Centers for Disease Control and Prevention (CDC), the U.S. Food and Drug Administration (FDA), the U.S. Department of Agriculture (USDA) and many other government agencies involved in promotion and regulation of health activities around the world are vigorously engaged in developing programs intended to monitor for the emergence of antimicrobial resistance and to decrease use of antimicrobial drugs where possible.