Simple Solutions Reflect Misunderstanding of Animal Antibiotic Use

LETTER

I read the recent paper by Metz and Shlaes (1) in which the authors detail eight additional ways to mitigate antibiotic resistance. While I agree that efforts are necessary in both veterinary and human medicine to control antibacterial resistance, several of the proposed “ways” to deal with this issue demonstrate an unfortunate lack of understanding of antibiotics used for treatment of animal diseases.

First, the authors suggest that the USDA create a “Non-Feed-Antibiotics” certification program for food products which conflates the use of antimicrobials for growth promotion with the therapeutic uses in food animals. Oral dosing of antibiotics through medicated feeds is an efficient method for administering treatment of bacterial diseases to groups of infected animals, and removal would present a significant risk to animal welfare. Also, the addition of another food label would add to the confusion that consumers currently face when purchasing food products. For example, there are currently 24 different labels that can be affixed to poultry products sold in the United States. Of these, the USDA recognizes only two as highly useful in that they are meaningful and verified (2). Moreover, the USDA would be discriminating against those producers which are using safe and effective antimicrobials approved by a sister agency, the FDA, by arbitrarily labeling feed use antibiotics as something to avoid.

Next, the authors recommend that the EPA expand their regulatory jurisdiction to livestock antibiotics under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) regulations. FIFRA regulations allow the EPA to regulate plant use only, and food animal antibiotic use clearly falls under the jurisdiction of the FDA Center for Veterinary Medicine (CVM). For the EPA to expand their jurisdiction, new legislation and regulation would be needed.

Moreover, the authors fail to indicate that the current CVM approval process for new veterinary drugs requires environmental, human food safety, and microbial safety assessments. Along with their failure to understand the approval process for veterinary drugs, they also minimize the effect of CVM Guidance 209/213 for removal of the growth promotion claims. In order to fully comply with these guidance documents, the industry must remove all growth promotion claims regardless of their current commercial status and move all antibiotic use to veterinary control. The authors then state that this includes only the “medically important” antibiotics but that other antimicrobial products will remain on the market with growth claims. This statement is misleading, as those non-medically important antimicrobials are predominantly the coccidiostatic ionophores which are classified as antibiotics in the United States but not in other regions of the world.

The issue of antibiotic resistance is complex, and while it is easy to advocate simple solutions, we must be aware of inadvertent consequences. The increase in the therapeutic use of antibiotics in livestock and the recent increase in rates of vancomycin-resistant enterococcus (VRE) infections in Denmark after the removal of antibiotic growth promotion claims are but two examples (3, 4). The most important way to control antibacterial resistance is, first, to develop new, effective, and separate antibacterials for both veterinary medicine and human medicine and, second, to ensure that antimicrobials are used judiciously under the direction of a veterinarian or physician.